boot-architecture March 2021

boot-architecture@lists.linaro.org

15 participants
16 discussions

RE: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

by raghu.ncstate＠icloud.com

Julius, Simon, It appears there are opinions you carry around UUID being complicated, bloated, code being an eyesore, parsing these lists early with MMU/Caches disabled, calculating checksums etc. While there is certainly a LOT of truth to those statements, these concerns need to be put into context and may not necessarily apply to all platforms running TF-A. Standardization and interoperability may be valued more on some platforms and some of the bloat and performance issues may be worth those tradeoffs. Some of these concerns may not even apply on powerful CPU’s and SoC’s with lots of memory. Also a quick grep for “uuid” in the TF-A repository shows that there is significant use of UUID’s for FIP, some SMC’s, secure partitions etc so use of UUID is not something new to TF-A. While there are many ways to solve the same problem, there are also potential dis-advantages to something like the mechanism pointed out below. For example, this is yet another solution to an already solved problem. If we use UEFI hob’s, the code and problem has been solved for decades and there is code re-use possible and that *potentially*(opinions may vary) is better for security as there have been eyes on it for long and is more stable.(I’m very aware UEFI is not the gold standard for security, but again, it is a blanket statement to say all UEFI code is bad). Does the method mentioned below allow you to create a dynamic list of arbitrary lengths and NOT lists of lengths decided at compile time? It appears that it is mainly being used on lists fixed at compile time. What about interoperability with UEFI? Coreboot is great for platforms/companies that use it but what about platforms that *must* use UEFI for various reasons? Do we need a conversion from the method below to a UEFI HOB if BL33 is UEFI? Clearly the solution below was tailored to coreboot. We can support multiple ways in the same code base through build and run time options and a platform should be free to make calls on whether the problems you mentioned below really apply or not. What is a pain to do(having co-ordination with multiple companies vs vendor defined tags/UUID’s) is also subjective and whether or not it is overstated is matter of opinion/context. I think it may be best to discuss this in the call and understand the requirements fully. It may turn out that what you have proposed below works anyway 😊 Thanks Raghu From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Julius Werner via TF-A Sent: Wednesday, March 24, 2021 7:44 PM To: Simon Glass <sjg(a)chromium.org> Cc: Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com>; Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org>; tf-a(a)lists.trustedfirmware.org; U-Boot Mailing List <u-boot(a)lists.denx.de>; Paul Isaac's <paul.isaacs(a)linaro.org>; Ron Minnich <rminnich(a)google.com> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages Just want to point out that TF-A currently already supports a (very simple) mechanism like this: https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/… https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/… https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/… It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31. I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once. On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A <tf-a(a)lists.trustedfirmware.org <mailto:tf-a@lists.trustedfirmware.org> > wrote: Hi Harb, On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com <mailto:abdulhamid@os.amperecomputing.com> > wrote: Hello Folks, Appreciate the feedback and replies on this. Glad to see that there is interest in this topic. 😊 I try to address the comments/feedback from Francois and Simon below…. <mailto:francois.ozog@linaro.org> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT. Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases. The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM). Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model: 1. “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances 2. “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances. Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code. To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software. I understand the versatility of DT, but I see two major problems with DT: * DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained. * DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob) I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs). Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls. Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call. <mailto:sjg@chromium.org> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for. That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about. The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use. I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors. True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code: #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) (etc.) static struct guid_name { efi_guid_t guid; const char *name; } guid_name[] = { { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" }, { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" }, { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" }, (never figured out what those two are) { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" }, { {}, "zero-guid" }, {} }; static const char *guid_to_name(const efi_guid_t *guid) { struct guid_name *entry; for (entry = guid_name; entry->name; entry++) { if (!guidcmp(guid, &entry->guid)) return entry->name; } return NULL; } Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory. We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB. Indeed. There is certainly value in both approaches. Regards, Simon Thanks, --Harb From: François Ozog <francois.ozog(a)linaro.org <mailto:francois.ozog@linaro.org> > Sent: Tuesday, March 23, 2021 10:00 AM To: François Ozog <francois.ozog(a)linaro.org <mailto:francois.ozog@linaro.org> >; Ron Minnich <rminnich(a)google.com <mailto:rminnich@google.com> >; Paul Isaac's <paul.isaacs(a)linaro.org <mailto:paul.isaacs@linaro.org> > Cc: Simon Glass <sjg(a)chromium.org <mailto:sjg@chromium.org> >; Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com <mailto:abdulhamid@os.amperecomputing.com> >; Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org <mailto:boot-architecture@lists.linaro.org> >; tf-a(a)lists.trustedfirmware.org <mailto:tf-a@lists.trustedfirmware.org> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages +Ron Minnich <mailto:rminnich@google.com> +Paul Isaac's <mailto:paul.isaacs@linaro.org> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts. On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A <tf-a(a)lists.trustedfirmware.org <mailto:tf-a@lists.trustedfirmware.org> > wrote: Hi, I propose we cover the topic at the next Trusted Substrate <https://collaborate.linaro.org/display/TS/Trusted+Substrate+Home> zoom call <https://linaro-org.zoom.us/j/94563644892> on April 8th 4pm CET. The agenda: ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions. runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing. For additional background on existing metadata: <https://uefi.org/sites/default/files/resources/PI_Spec_1_7_final_Jan_2019.p…> UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains. HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested). There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report <https://docs.google.com/document/d/1CLkhLRaz_zcCq44DLGmPZQFPbYHOC6nzPowaL0X…> ) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2. I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls). Requirements (to be validated): - ACPI and DT hardware descriptions. - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot) - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages) - support secure world device assignment Cheers FF On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg(a)chromium.org <mailto:sjg@chromium.org> > wrote: Hi, Can I suggest using bloblist for this instead? It is lightweight, easier to parse, doesn't have GUIDs and is already used within U-Boot for passing info between SPL/U-Boot, etc. Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist Header file describes the format: https://github.com/u-boot/u-boot/blob/master/include/bloblist.h Full set of unit tests: https://github.com/u-boot/u-boot/blob/master/test/bloblist.c Regards, Simon On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog(a)linaro.org <mailto:francois.ozog@linaro.org> > wrote: > > +Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org <mailto:boot-architecture@lists.linaro.org> > > > standardization is very much welcomed here and need to accommodate a very > diverse set of situations. > For example, TEE OS may need to pass memory reservations to BL33 or > "capture" a device for the secure world. > > I have observed a number of architectures: > 1) pass information from BLx to BLy in the form of a specific object > 2) BLx called by BLy by a platform specific SMC to get information > 3) BLx called by BLy by a platform specific SMC to perform Device Tree > fixups > > I also imagined a standardized "broadcast" FF-A call so that any firmware > element can either provide information or "do something". > > My understanding of your proposal is about standardizing on architecture 1) > with the HOB format. > > The advantage of the HOB is simplicity but it may be difficult to implement > schemes such as pruning a DT because device assignment in the secure world. > > In any case, it looks feasible to have TF-A and OP-TEE complement the list > of HOBs to pass information downstream (the bootflow). > > It would be good to start with building the comprehensive list of > information that need to be conveyed between firmware elements: > > information. | authoritative entity | reporting entity | information > exchanged: > dram | TFA | TFA | > <format to be detailed, NUMA topology to build the SRAT table or DT > equivalent?> > PSCI | SCP | TFA? | > SCMI | SCP or TEE-OS | TFA? TEE-OS?| > secure SRAM | TFA. | TFA. | > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | > other? | | > | > > Cheers > > FF > > > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < > tf-a(a)lists.trustedfirmware.org <mailto:tf-a@lists.trustedfirmware.org> > wrote: > > > Hello Folks, > > > > > > > > I'm emailing to start an open discussion about the adoption of a concept > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware > > Framework Architecture (FFA). This is something that is a pretty major > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s > > designed to enable a broad range of highly configurable datacenter > > platforms. > > > > > > > > > > > > What is a HOB (Background)? > > > > --------------------------- > > > > UEFI PI spec describes a particular definition for how HOB may be used for > > transitioning between the PEI and DXE boot phases, which is a good > > reference point for this discussion, but not necessarily the exact solution > > appropriate for TF-A. > > > > > > > > A HOB is simply a dynamically generated data structure passed in between > > two boot phases. This is information that was obtained through discovery > > and needs to be passed forward to the next boot phase *once*, with no API > > needed to call back (e.g. no call back into previous firmware phase is > > needed to fetch this information at run-time - it is simply passed one time > > during boot). > > > > > > > > There may be one or more HOBs passed in between boot phases. If there are > > more than one HOB that needs to be passed, this can be in a form of a "HOB > > table", which (for example) could be a UUID indexed array of pointers to > > HOB structures, used to locate a HOB of interest (based on UUID). In such > > cases, instead of passing a single HOB, the boot phases may rely on passing > > the pointer to the HOB table. > > > > > > > > This has been extremely useful concept to employ on highly configurable > > systems that must rely on flexible discovery mechanisms to initialize and > > boot the system. This is especially helpful when you have multiple > > > > > > > > > > > > Why do we need HOBs in TF-A?: > > > > ----------------------------- > > > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in > > a way that is SoC specific *but* platform agnostic. This means that a > > single ARM SoC that a SiP may deliver to customers may provide a single > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad > > range of platform designs and configurations in order to boot a platform > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to > > achieve this, the platform configuration must be *discovered* instead of > > statically compiled as it is today in TF-A via device tree based > > enumeration. The mechanisms of discovery may differ broadly depending on > > the relevant industry standard, or in some cases may have rely on SiP > > specific discovery flows. > > > > > > > > For example: On server systems that support a broad range DIMM memory > > population/topologies, all the necessary information required to boot is > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an > > I2C bus. Leveraging the SPD bus, may platform variants could be supported > > with a single TF-A binary. Not only is this information required to > > initialize memory in early boot phases (e.g. BL2), the subsequent boot > > phases will also need this SPD info to construct a system physical address > > map and properly initialize the MMU based on the memory present, and where > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may > > need to generate standard firmware tables to the operating systems, such as > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT, > > SRAT, even NFIT if NVDIMM's are present). > > > > > > > > In short, it all starts with a standardized or vendor specific discovery > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of > > information to the next boot stages (e.g. BL31/BL32/BL33). > > > > > > > > Today, every HOB may be a vendor specific structure, but in the future > > there may be benefit of defining standard HOBs. This may be useful for > > memory discovery, passing the system physical address map, enabling TPM > > measured boot, and potentially many other common HOB use-cases. > > > > > > > > It would be extremely beneficial to the datacenter market segment if the > > TF-A community would adopt this concept of information passing between all > > boot phases as opposed to rely solely on device tree enumeration. This is > > not intended to replace device tree, rather intended as an alternative way > > to describe the info that must be discovered and dynamically generated. > > > > > > > > > > > > Conclusion: > > > > ----------- > > > > We are proposing that the TF-A community begin pursuing the adoption of > > HOBs as a mechanism used for information exchange between each boot stage > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we > > want to explore standardizing some HOB structures for the BL33 phase (e.g. > > UEFI HOB structures), but initially would like to agree on this being a > > useful mechanism used to pass information between each boot stage. > > > > > > > > Thanks, > > > > --Harb > > > > > > > > > > > > > > -- > > TF-A mailing list > > TF-A(a)lists.trustedfirmware.org <mailto:TF-A@lists.trustedfirmware.org> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > > > > > -- > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* > T: +33.67221.6485 > francois.ozog(a)linaro.org <mailto:francois.ozog@linaro.org> | Skype: ffozog > _______________________________________________ > boot-architecture mailing list > boot-architecture(a)lists.linaro.org <mailto:boot-architecture@lists.linaro.org> > https://lists.linaro.org/mailman/listinfo/boot-architecture -- <https://drive.google.com/a/linaro.org/uc?id=0BxTAygkus3RgQVhuNHMwUi1mYWc&ex…> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group T: +33.67221.6485 <mailto:francois.ozog@linaro.org> francois.ozog(a)linaro.org | Skype: ffozog -- TF-A mailing list TF-A(a)lists.trustedfirmware.org <mailto:TF-A@lists.trustedfirmware.org> https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- <https://drive.google.com/a/linaro.org/uc?id=0BxTAygkus3RgQVhuNHMwUi1mYWc&ex…> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group T: +33.67221.6485 <mailto:francois.ozog@linaro.org> francois.ozog(a)linaro.org | Skype: ffozog -- TF-A mailing list TF-A(a)lists.trustedfirmware.org <mailto:TF-A@lists.trustedfirmware.org> https://lists.trustedfirmware.org/mailman/listinfo/tf-a

3 years, 8 months

Glitching protection

by François Ozog

Hi Trusted Firmware M recently introduced protection against glitching at key decision points: https://github.com/mcu-tools/mcuboot/pull/776 To me this is a key mitigation element for companies that target PSA level 3 compliance which means hardware attacks resilience. I believe similar techniques need to be used in different projects involved in Linux secure booting (TF-A, OP-TEE, U-Boot, Linux kernel). Are there any efforts planned around this ? Is it feasible to have a "library" that could be integrated in different projects? Cheers FF

3 years, 8 months

RE: [TF-A] Firmware FuSa workshop

by Miklos Balint

To += op-tee(a)lists.trustedfirmware.org<mailto:op-tee@lists.trustedfirmware.org> From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of François Ozog via TF-A Sent: 26 March 2021 19:08 To: Heinrich Schuchardt <xypron.glpk(a)gmx.de> Cc: tf-a(a)lists.trustedfirmware.org; Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org>; Ilias Apalodimas <ilias.apalodimas(a)linaro.org> Subject: Re: [TF-A] Firmware FuSa workshop Le ven. 26 mars 2021 à 18:42, Heinrich Schuchardt <xypron.glpk(a)gmx.de<mailto:xypron.glpk@gmx.de>> a écrit : On 26.03.21 16:05, François Ozog wrote: > Hi, > > > Linaro is conducting an opportunity assessment to make OP-TEE ready for > functional safety sensitive environments. The goal is to present a plan to > Linaro members by the end of July 2021. > > The scope of the research is somewhat bigger because we can’t think of > OP-TEE without thinking of Trusted Firmware and Hafnium. The plan will > though not address those (unless we recognize we have to). We don’t think > U-Boot shall be part of the picture but we are welcoming contradictory > points of views. Hello François, Some boards boot via SPL->TF-A->U-Boot. Here U-Boot's SPL is relevant for OP-TEE's security. U-Boot can save variables via OP-TEE (implemented by Ilias). In this case OP-TEE has an implication on secure boot. I fully understand that these scenarios are not in the focus of the workshop. it may if companies have this particular flow in mind for safety certification. Our goal is not to make all boot flows safety ready but to identify which ones we need to consider. And the workshop may help in this identification. Best regards Heinrich > > We are organizing a 2 hours workshop on April 15th 9am CET to mostly hear > about use cases and ideas about Long Term Support requirements . We will > present the state of the research. > > The first use case is booting a safety certified type-1 hypervisor (open > source or commercial is irrelevant). > > But we know there are many more: please be ready to contribute. > > We think of more radical use cases: a safety payload is actually loaded as > a Secure Partition on top of Hafnium with OP-TEE or Zephyr used as a device > backends. In other words, Trust Zone hosts both safety and security worlds > , EL3 being the « software root of trust » pivot world. In those cases, > some cores never go out of secure state… > > > Agenda (to be refined) > > - > > Vision > - > > State of the research > <https://docs.google.com/presentation/u/0/d/1jWqu39gCF-5XzbFkodXsiVNJJLUN88B…> > - > > Use cases discussion > - > > What is the right scope? > - > > “Who do what” discussion (LTS, archiving...) > - > > Safety personnel (Linaro and contractors) discussion > - > > Other considerations from participants? > - > > Community organizations and funding? > - > > Closing and next steps > > > Should you want to participate and have not yet received an invite, please > contact me directly. > > Cordially, > > François-Frédéric > > PS: Please reach out should you want another date with a time compatible > with more time zones. This alternate date is not guaranteed though. > > -- [https://drive.google.com/a/linaro.org/uc?id=0BxTAygkus3RgQVhuNHMwUi1mYWc&ex…] François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group T: +33.67221.6485 francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org> | Skype: ffozog

3 years, 8 months

Firmware FuSa workshop

by François Ozog

Hi, Linaro is conducting an opportunity assessment to make OP-TEE ready for functional safety sensitive environments. The goal is to present a plan to Linaro members by the end of July 2021. The scope of the research is somewhat bigger because we can’t think of OP-TEE without thinking of Trusted Firmware and Hafnium. The plan will though not address those (unless we recognize we have to). We don’t think U-Boot shall be part of the picture but we are welcoming contradictory points of views. We are organizing a 2 hours workshop on April 15th 9am CET to mostly hear about use cases and ideas about Long Term Support requirements . We will present the state of the research. The first use case is booting a safety certified type-1 hypervisor (open source or commercial is irrelevant). But we know there are many more: please be ready to contribute. We think of more radical use cases: a safety payload is actually loaded as a Secure Partition on top of Hafnium with OP-TEE or Zephyr used as a device backends. In other words, Trust Zone hosts both safety and security worlds , EL3 being the « software root of trust » pivot world. In those cases, some cores never go out of secure state… Agenda (to be refined) - Vision - State of the research <https://docs.google.com/presentation/u/0/d/1jWqu39gCF-5XzbFkodXsiVNJJLUN88B…> - Use cases discussion - What is the right scope? - “Who do what” discussion (LTS, archiving...) - Safety personnel (Linaro and contractors) discussion - Other considerations from participants? - Community organizations and funding? - Closing and next steps Should you want to participate and have not yet received an invite, please contact me directly. Cordially, François-Frédéric PS: Please reach out should you want another date with a time compatible with more time zones. This alternate date is not guaranteed though. -- François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* T: +33.67221.6485 francois.ozog(a)linaro.org | Skype: ffozog

3 years, 9 months

Re: [TF-A] Glitching protection

by Joanna Farley

Hi François, The TF-A team members have thought about trying to explore the use of more mitigations for Side Channel attacks along the lines of "Canary In the Coalmine" type techniques to as you say build additional resilience and as you can expect the techniques used by our peer TF-M project are one we would like to explore. I would not say this is a plan as such but definitely something already listed on our backlog. As to if the TF-M code can be reused that would need to be explored more. Cheers Joanna On 26/03/2021, 14:12, "TF-A on behalf of François Ozog via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Hi Trusted Firmware M recently introduced protection against glitching at key decision points: https://github.com/mcu-tools/mcuboot/pull/776 To me this is a key mitigation element for companies that target PSA level 3 compliance which means hardware attacks resilience. I believe similar techniques need to be used in different projects involved in Linux secure booting (TF-A, OP-TEE, U-Boot, Linux kernel). Are there any efforts planned around this ? Is it feasible to have a "library" that could be integrated in different projects? Cheers FF -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

3 years, 9 months

Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

by Julius Werner

Just want to point out that TF-A currently already supports a (very simple) mechanism like this: https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/… https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/… https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/… It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31. I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once. On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A < tf-a(a)lists.trustedfirmware.org> wrote: > Hi Harb, > > On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS < > abdulhamid(a)os.amperecomputing.com> wrote: > >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to see that there is >> interest in this topic. 😊 >> >> >> >> I try to address the comments/feedback from Francois and Simon below…. >> >> >> >> @François Ozog <francois.ozog(a)linaro.org> – happy to discuss this on a >> zoom call. I will make that time slot work, and will be available to >> attend April 8, 4pm CT. >> >> >> >> Note that I’m using the term “HOB” here more generically, as there are >> typically vendor specific structures beyond the resource descriptor HOB, >> which provides only a small subset of the information that needs to be >> passed between the boot phases. >> >> >> >> The whole point here is to provide mechanism to develop firmware that we >> can build ARM Server SoC’s that support **any** BL33 payload (e.g. EDK2, >> AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some >> point). In other-words, we are trying to come up with a TF-A that would >> be completely agnostic to the implementation of BL33 (i.e. BL33 is built >> completely independently by a separate entity – e.g. an ODM/OEM). >> >> >> >> Keep in mind, in the server/datacenter market segment we are not building >> vertically integrated systems with a single entity compiling >> firmware/software stacks like most folks in TF-A have become use to. There >> are two categories of higher level firmware code blobs in the >> server/datacenter model: >> >> 1. “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, >> BL31, and **possibly** one or more BL32 instances >> 2. “Platform” or “board” firmware – in TF-A this may map to BL33 and * >> *possibly** one or more BL32 instances. >> >> >> >> Even the platform firmware stack could be further fragmented by having >> multiple entities involved in delivering the entire firmware stack: IBVs, >> ODMs, OEMs, CSPs, and possibly even device vendor code. >> >> >> >> To support a broad range of platform designs with a broad range of memory >> devices, we need a crisp and clear contract between the SoC firmware that >> initializes memory (e.g. BL2) and how that platform boot firmware (e.g. >> BL33) gathers information about what memory that was initialized, at what >> speeds, NUMA topology, and many other relevant information that needs to be >> known and comprehended by the platform firmware and eventually by the >> platform software. >> >> >> >> I understand the versatility of DT, but I see two major problems with DT: >> >> - DT requires more complicated parsing to get properties, and even >> more complex to dynamically set properties – this HOB structures may need >> to be generated in boot phases where DDR is not available, and therefore we >> will be extremely memory constrained. >> - DT is probably overkill for this purpose – We really just want a >> list of pointers to simple C structures that code cast (e.g. JEDEC SPD data >> blob) >> >> >> >> I think that we should not mix the efforts around DT/ACPI specs with what >> we are doing here, because those specs and concepts were developed for a >> completely different purpose (i.e. abstractions needed for OS / RTOS >> software, and not necessarily suitable for firmware-to-firmware hand-offs). >> >> >> >> Frankly, I would personally push back pretty hard on defining SMC’s for >> something that should be one way information passing. Every SMC we add is >> another attack vector to the secure world and an increased burden on the >> folks that have to do security auditing and threat analysis. I see no >> benefit in exposing these boot/HOB/BOB structures at run-time via SMC >> calls. >> >> >> >> Please do let me know if you disagree and why. Look forward to >> discussing on this thread or on the call. >> >> >> >> @Simon Glass <sjg(a)chromium.org> - Thanks for the pointer to >> bloblist. I briefly reviewed and it seems like a good baseline for what >> we may be looking for. >> >> >> >> That being said, I would say that there is some benefit in having some >> kind of unique identifiers (e.g. UUID or some unique signature) so that we >> can tie standardized data structures (based on some future TBD specs) to a >> particular ID. For example, if the TPM driver in BL33 is looking for the >> TPM structure in the HOB/BOB list, and may not care about the other data >> blobs. The driver needs a way to identify and locate the blob it cares >> about. >> > > The tag is intended to serve that purpose, although perhaps it should > switch from an auto-allocating enum to one with explicit values for each > entry and a range for 'local' use. > >> >> >> I guess we can achieve this with the tag, but the problem with tag when >> you have eco-system with a lot of parties doing parallel development, you >> can end up with tag collisions and folks fighting about who has rights to >> what tag values. We would need some official process for folks to register >> tags for whatever new structures we define, or maybe some tag range for >> vendor specific structures. This comes with a lot of pain and >> bureaucracy. On the other hand, UUID has been a proven way to make it easy >> to just define your own blobs with **either** standard or vendor >> specific structures without worry of ID collisions between vendors. >> > > True. I think the pain is overstated, though. In this case I think we > actually want something that can be shared between projects and orgs, so > some amount of coordination could be considered a benefit. It could just be > a github pull request. I find the UUID unfriendly and not just to code size > and eyesight! Trying to discover what GUIDs mean or are valid is quite > tricky. E.g. see this code: > > #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ > EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ > 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) > (etc.) > > static struct guid_name { > efi_guid_t guid; > const char *name; > } guid_name[] = { > { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, > { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, > { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" }, > { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, > { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, > { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, > { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" }, > { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" }, > (never figured out what those two are) > > { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, > { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, > { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" }, > { {}, "zero-guid" }, > {} > }; > > static const char *guid_to_name(const efi_guid_t *guid) > { > struct guid_name *entry; > > for (entry = guid_name; entry->name; entry++) { > if (!guidcmp(guid, &entry->guid)) > return entry->name; > } > > return NULL; > } > > Believe it or not it took a fair bit of effort to find just that small > list, with nearly every one in a separate doc, from memory. > > >> >> We can probably debate whether there is any value in GUID/UUID or not >> during the call… but again, boblist seems like a reasonable starting point >> as an alternative to HOB. >> > > Indeed. There is certainly value in both approaches. > > Regards, > Simon > > >> >> >> Thanks, >> >> --Harb >> >> >> >> *From:* François Ozog <francois.ozog(a)linaro.org> >> *Sent:* Tuesday, March 23, 2021 10:00 AM >> *To:* François Ozog <francois.ozog(a)linaro.org>; Ron Minnich < >> rminnich(a)google.com>; Paul Isaac's <paul.isaacs(a)linaro.org> >> *Cc:* Simon Glass <sjg(a)chromium.org>; Harb Abdulhamid OS < >> abdulhamid(a)os.amperecomputing.com>; Boot Architecture Mailman List < >> boot-architecture(a)lists.linaro.org>; tf-a(a)lists.trustedfirmware.org >> *Subject:* Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for >> information passing between boot stages >> >> >> >> +Ron Minnich <rminnich(a)google.com> +Paul Isaac's <paul.isaacs(a)linaro.org> >> >> >> >> >> Adding Ron and Paul because I think this interface should be also >> benefiting LinuxBoot efforts. >> >> >> >> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A < >> tf-a(a)lists.trustedfirmware.org> wrote: >> >> Hi, >> >> >> >> I propose we cover the topic at the next Trusted Substrate >> <https://collaborate.linaro.org/display/TS/Trusted+Substrate+Home> zoom >> call <https://linaro-org.zoom.us/j/94563644892> on April 8th 4pm CET. >> >> >> >> The agenda: >> >> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, >> S-EL2, SCP) to adapt hardware description to some runtime conditions. >> >> runtime conditions here relates to DRAM size and topology detection, >> secure DRAM memory carvings, PSCI and SCMI interface publishing. >> >> >> >> For additional background on existing metadata: UEFI Platform >> Initialization Specification Version 1.7 >> <https://uefi.org/sites/default/files/resources/PI_Spec_1_7_final_Jan_2019.p…> >> , 5.5 Resource Descriptor HOB >> >> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. >> >> This HOB lacks memory NUMA attachment or something that could be related >> to fill SRAT table for ACPI or relevant DT proximity domains. >> >> HOB is not consistent accros platforms: some platforms (Arm) lists memory >> from the booting NUMA node, other platforms (x86) lists all memory from all >> NUMA nodes. (At least this is the case on the two platforms I tested). >> >> >> >> There are two proposals to use memory structures from SPL/BLx up to the >> handover function (as defined in the Device Tree technical report >> <https://docs.google.com/document/d/1CLkhLRaz_zcCq44DLGmPZQFPbYHOC6nzPowaL0X…>) >> which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or >> EDK2. >> >> I would propose we also discuss possibility of FF-A interface to actually >> query information or request actions to be done (this is a model actually >> used in some SoCs with proprietary SMC calls). >> >> >> >> Requirements (to be validated): >> >> - ACPI and DT hardware descriptions. >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, >> TF-A/LinuxBoot) >> >> - at least allows complete DRAM description and "persistent" usage >> (reserved areas for secure world or other usages) >> >> - support secure world device assignment >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> >> >> On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg(a)chromium.org> wrote: >> >> Hi, >> >> Can I suggest using bloblist for this instead? It is lightweight, >> easier to parse, doesn't have GUIDs and is already used within U-Boot >> for passing info between SPL/U-Boot, etc. >> >> Docs here: >> https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist >> Header file describes the format: >> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h >> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog(a)linaro.org> >> wrote: >> > >> > +Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org> >> > >> > standardization is very much welcomed here and need to accommodate a >> very >> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations to BL33 or >> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of a specific object >> > 2) BLx called by BLy by a platform specific SMC to get information >> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree >> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so that any >> firmware >> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing on >> architecture 1) >> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may be difficult to >> implement >> > schemes such as pruning a DT because device assignment in the secure >> world. >> > >> > In any case, it looks feasible to have TF-A and OP-TEE complement the >> list >> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensive list of >> > information that need to be conveyed between firmware elements: >> > >> > information. | authoritative entity | reporting entity | information >> > exchanged: >> > dram | TFA | TFA | >> > <format to be detailed, NUMA topology to build the SRAT table or DT >> > equivalent?> >> > PSCI | SCP | TFA? | >> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a(a)lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about the adoption of a >> concept >> > > known as "hand-off blocks" or HOB to become a part of the TF-A >> Firmware >> > > Framework Architecture (FFA). This is something that is a pretty >> major >> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s >> > > designed to enable a broad range of highly configurable datacenter >> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOB may be >> used for >> > > transitioning between the PEI and DXE boot phases, which is a good >> > > reference point for this discussion, but not necessarily the exact >> solution >> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structure passed in >> between >> > > two boot phases. This is information that was obtained through >> discovery >> > > and needs to be passed forward to the next boot phase *once*, with no >> API >> > > needed to call back (e.g. no call back into previous firmware phase is >> > > needed to fetch this information at run-time - it is simply passed >> one time >> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between boot phases. If >> there are >> > > more than one HOB that needs to be passed, this can be in a form of a >> "HOB >> > > table", which (for example) could be a UUID indexed array of pointers >> to >> > > HOB structures, used to locate a HOB of interest (based on UUID). In >> such >> > > cases, instead of passing a single HOB, the boot phases may rely on >> passing >> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highly >> configurable >> > > systems that must rely on flexible discovery mechanisms to initialize >> and >> > > boot the system. This is especially helpful when you have multiple >> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server >> SoC in >> > > a way that is SoC specific *but* platform agnostic. This means that a >> > > single ARM SoC that a SiP may deliver to customers may provide a >> single >> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a >> broad >> > > range of platform designs and configurations in order to boot a >> platform >> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order >> to >> > > achieve this, the platform configuration must be *discovered* instead >> of >> > > statically compiled as it is today in TF-A via device tree based >> > > enumeration. The mechanisms of discovery may differ broadly >> depending on >> > > the relevant industry standard, or in some cases may have rely on SiP >> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad range DIMM memory >> > > population/topologies, all the necessary information required to boot >> is >> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over >> an >> > > I2C bus. Leveraging the SPD bus, may platform variants could be >> supported >> > > with a single TF-A binary. Not only is this information required to >> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot >> > > phases will also need this SPD info to construct a system physical >> address >> > > map and properly initialize the MMU based on the memory present, and >> where >> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) >> may >> > > need to generate standard firmware tables to the operating systems, >> such as >> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. >> SLIT, >> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendor specific >> discovery >> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of >> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, but in the future >> > > there may be benefit of defining standard HOBs. This may be useful >> for >> > > memory discovery, passing the system physical address map, enabling >> TPM >> > > measured boot, and potentially many other common HOB use-cases. >> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter market segment if >> the >> > > TF-A community would adopt this concept of information passing >> between all >> > > boot phases as opposed to rely solely on device tree enumeration. >> This is >> > > not intended to replace device tree, rather intended as an >> alternative way >> > > to describe the info that must be discovered and dynamically >> generated. >> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuing the adoption >> of >> > > HOBs as a mechanism used for information exchange between each boot >> stage >> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term >> we >> > > want to explore standardizing some HOB structures for the BL33 phase >> (e.g. >> > > UEFI HOB structures), but initially would like to agree on this being >> a >> > > useful mechanism used to pass information between each boot stage. >> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A(a)lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* >> > T: +33.67221.6485 >> > francois.ozog(a)linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture(a)lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> >> >> >> >> -- >> >> *François-Frédéric Ozog* | *Director Linaro Edge & Fog Computing Group* >> >> T: +33.67221.6485 >> francois.ozog(a)linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A(a)lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> *François-Frédéric Ozog* | *Director Linaro Edge & Fog Computing Group* >> >> T: +33.67221.6485 >> francois.ozog(a)linaro.org | Skype: ffozog >> >> >> > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >

3 years, 9 months

Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

by François Ozog

+Ron Minnich <rminnich(a)google.com> +Paul Isaac's <paul.isaacs(a)linaro.org> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts. On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A < tf-a(a)lists.trustedfirmware.org> wrote: > Hi, > > I propose we cover the topic at the next Trusted Substrate > <https://collaborate.linaro.org/display/TS/Trusted+Substrate+Home> zoom > call <https://linaro-org.zoom.us/j/94563644892> on April 8th 4pm CET. > > The agenda: > ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, > S-EL2, SCP) to adapt hardware description to some runtime conditions. > runtime conditions here relates to DRAM size and topology detection, > secure DRAM memory carvings, PSCI and SCMI interface publishing. > > For additional background on existing metadata: UEFI Platform > Initialization Specification Version 1.7 > <https://uefi.org/sites/default/files/resources/PI_Spec_1_7_final_Jan_2019.p…> > , 5.5 Resource Descriptor HOB > Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. > This HOB lacks memory NUMA attachment or something that could be related > to fill SRAT table for ACPI or relevant DT proximity domains. > HOB is not consistent accros platforms: some platforms (Arm) lists memory > from the booting NUMA node, other platforms (x86) lists all memory from all > NUMA nodes. (At least this is the case on the two platforms I tested). > > There are two proposals to use memory structures from SPL/BLx up to the > handover function (as defined in the Device Tree technical report > <https://docs.google.com/document/d/1CLkhLRaz_zcCq44DLGmPZQFPbYHOC6nzPowaL0X…>) > which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or > EDK2. > I would propose we also discuss possibility of FF-A interface to actually > query information or request actions to be done (this is a model actually > used in some SoCs with proprietary SMC calls). > > Requirements (to be validated): > - ACPI and DT hardware descriptions. > - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) > - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot) > - at least allows complete DRAM description and "persistent" usage > (reserved areas for secure world or other usages) > - support secure world device assignment > > Cheers > > FF > > > On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg(a)chromium.org> wrote: > >> Hi, >> >> Can I suggest using bloblist for this instead? It is lightweight, >> easier to parse, doesn't have GUIDs and is already used within U-Boot >> for passing info between SPL/U-Boot, etc. >> >> Docs here: >> https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist >> Header file describes the format: >> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h >> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog(a)linaro.org> >> wrote: >> > >> > +Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org> >> > >> > standardization is very much welcomed here and need to accommodate a >> very >> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations to BL33 or >> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of a specific object >> > 2) BLx called by BLy by a platform specific SMC to get information >> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree >> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so that any >> firmware >> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing on >> architecture 1) >> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may be difficult to >> implement >> > schemes such as pruning a DT because device assignment in the secure >> world. >> > >> > In any case, it looks feasible to have TF-A and OP-TEE complement the >> list >> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensive list of >> > information that need to be conveyed between firmware elements: >> > >> > information. | authoritative entity | reporting entity | information >> > exchanged: >> > dram | TFA | TFA | >> > <format to be detailed, NUMA topology to build the SRAT table or DT >> > equivalent?> >> > PSCI | SCP | TFA? | >> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a(a)lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about the adoption of a >> concept >> > > known as "hand-off blocks" or HOB to become a part of the TF-A >> Firmware >> > > Framework Architecture (FFA). This is something that is a pretty >> major >> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s >> > > designed to enable a broad range of highly configurable datacenter >> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOB may be >> used for >> > > transitioning between the PEI and DXE boot phases, which is a good >> > > reference point for this discussion, but not necessarily the exact >> solution >> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structure passed in >> between >> > > two boot phases. This is information that was obtained through >> discovery >> > > and needs to be passed forward to the next boot phase *once*, with no >> API >> > > needed to call back (e.g. no call back into previous firmware phase is >> > > needed to fetch this information at run-time - it is simply passed >> one time >> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between boot phases. If >> there are >> > > more than one HOB that needs to be passed, this can be in a form of a >> "HOB >> > > table", which (for example) could be a UUID indexed array of pointers >> to >> > > HOB structures, used to locate a HOB of interest (based on UUID). In >> such >> > > cases, instead of passing a single HOB, the boot phases may rely on >> passing >> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highly >> configurable >> > > systems that must rely on flexible discovery mechanisms to initialize >> and >> > > boot the system. This is especially helpful when you have multiple >> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server >> SoC in >> > > a way that is SoC specific *but* platform agnostic. This means that a >> > > single ARM SoC that a SiP may deliver to customers may provide a >> single >> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a >> broad >> > > range of platform designs and configurations in order to boot a >> platform >> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order >> to >> > > achieve this, the platform configuration must be *discovered* instead >> of >> > > statically compiled as it is today in TF-A via device tree based >> > > enumeration. The mechanisms of discovery may differ broadly >> depending on >> > > the relevant industry standard, or in some cases may have rely on SiP >> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad range DIMM memory >> > > population/topologies, all the necessary information required to boot >> is >> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over >> an >> > > I2C bus. Leveraging the SPD bus, may platform variants could be >> supported >> > > with a single TF-A binary. Not only is this information required to >> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot >> > > phases will also need this SPD info to construct a system physical >> address >> > > map and properly initialize the MMU based on the memory present, and >> where >> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) >> may >> > > need to generate standard firmware tables to the operating systems, >> such as >> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. >> SLIT, >> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendor specific >> discovery >> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of >> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, but in the future >> > > there may be benefit of defining standard HOBs. This may be useful >> for >> > > memory discovery, passing the system physical address map, enabling >> TPM >> > > measured boot, and potentially many other common HOB use-cases. >> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter market segment if >> the >> > > TF-A community would adopt this concept of information passing >> between all >> > > boot phases as opposed to rely solely on device tree enumeration. >> This is >> > > not intended to replace device tree, rather intended as an >> alternative way >> > > to describe the info that must be discovered and dynamically >> generated. >> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuing the adoption >> of >> > > HOBs as a mechanism used for information exchange between each boot >> stage >> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term >> we >> > > want to explore standardizing some HOB structures for the BL33 phase >> (e.g. >> > > UEFI HOB structures), but initially would like to agree on this being >> a >> > > useful mechanism used to pass information between each boot stage. >> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A(a)lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* >> > T: +33.67221.6485 >> > francois.ozog(a)linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture(a)lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> > > > -- > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* > T: +33.67221.6485 > francois.ozog(a)linaro.org | Skype: ffozog > > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > -- François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* T: +33.67221.6485 francois.ozog(a)linaro.org | Skype: ffozog

3 years, 9 months

Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

by Bill Fletcher

Adding Andrea On Wed, 24 Mar 2021 at 13:55, Joanna Farley via TF-A < tf-a(a)lists.trustedfirmware.org> wrote: > Hi Harb and others, > > > > This thread is now multi-mailing list and I can see some broader needs and > opinions on aspects not directly defined by the TF-A project such as > differing information exchange formats. However, this is definitely > something the TF-A project can try and help provide enablement for to help > with the goal of supplying support for single or common TF-A binaries builds > for different images. TF-A already have some limited support in this space > and are considering how this can be extended given some of the needs > expressed here. Folks on the TF-A project are studying the below and will > propose soon some ideas on how TF-A could provide more versatile enablement > in this space shortly. > > > > Thanks > > > > Joanna > > > > *From: *TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of > François Ozog via TF-A <tf-a(a)lists.trustedfirmware.org> > *Reply to: *François Ozog <francois.ozog(a)linaro.org> > *Date: *Wednesday, 24 March 2021 at 08:34 > *To: *Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com> > *Cc: *"tf-a(a)lists.trustedfirmware.org" <tf-a(a)lists.trustedfirmware.org>, > Simon Glass <sjg(a)chromium.org>, Boot Architecture Mailman List < > boot-architecture(a)lists.linaro.org>, Paul Isaac's <paul.isaacs(a)linaro.org>, > Ron Minnich <rminnich(a)google.com> > *Subject: *Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for > information passing between boot stages > > > > > > > > On Tue, 23 Mar 2021 at 23:39, Harb Abdulhamid OS < > abdulhamid(a)os.amperecomputing.com> wrote: > > Hello Folks, > > Appreciate the feedback and replies on this. Glad to see that there is > interest in this topic. 😊 > > > > I try to address the comments/feedback from Francois and Simon below…. > > > > @François Ozog <francois.ozog(a)linaro.org> – happy to discuss this on a > zoom call. I will make that time slot work, and will be available to > attend April 8, 4pm CT. > > > > Note that I’m using the term “HOB” here more generically, as there are > typically vendor specific structures beyond the resource descriptor HOB, > which provides only a small subset of the information that needs to be > passed between the boot phases. > > > > The whole point here is to provide mechanism to develop firmware that we > can build ARM Server SoC’s that support **any** BL33 payload (e.g. EDK2, > AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some > point). In other-words, we are trying to come up with a TF-A that would > be completely agnostic to the implementation of BL33 (i.e. BL33 is built > completely independently by a separate entity – e.g. an ODM/OEM). > > > > Keep in mind, in the server/datacenter market segment we are not building > vertically integrated systems with a single entity compiling > firmware/software stacks like most folks in TF-A have become use to. There > are two categories of higher level firmware code blobs in the > server/datacenter model: > > 1. “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, > BL31, and **possibly** one or more BL32 instances > 2. “Platform” or “board” firmware – in TF-A this may map to BL33 and * > *possibly** one or more BL32 instances. > > > > Even the platform firmware stack could be further fragmented by having > multiple entities involved in delivering the entire firmware stack: IBVs, > ODMs, OEMs, CSPs, and possibly even device vendor code. > > > > To support a broad range of platform designs with a broad range of memory > devices, we need a crisp and clear contract between the SoC firmware that > initializes memory (e.g. BL2) and how that platform boot firmware (e.g. > BL33) gathers information about what memory that was initialized, at what > speeds, NUMA topology, and many other relevant information that needs to be > known and comprehended by the platform firmware and eventually by the > platform software. > > > > I understand the versatility of DT, but I see two major problems with DT: > > - DT requires more complicated parsing to get properties, and even > more complex to dynamically set properties – this HOB structures may need > to be generated in boot phases where DDR is not available, and therefore we > will be extremely memory constrained. > - DT is probably overkill for this purpose – We really just want a > list of pointers to simple C structures that code cast (e.g. JEDEC SPD data > blob) > > > > I think that we should not mix the efforts around DT/ACPI specs with what > we are doing here, because those specs and concepts were developed for a > completely different purpose (i.e. abstractions needed for OS / RTOS > software, and not necessarily suitable for firmware-to-firmware hand-offs). > > > > Frankly, I would personally push back pretty hard on defining SMC’s for > something that should be one way information passing. Every SMC we add is > another attack vector to the secure world and an increased burden on the > folks that have to do security auditing and threat analysis. I see no > benefit in exposing these boot/HOB/BOB structures at run-time via SMC > calls. > > > > Please do let me know if you disagree and why. Look forward to discussing > on this thread or on the call. > > > > I am not tied to a particular data representation and using SMC to just > pass data structures is overkill as you say. The SMC model seems useful to > do complex things like device assignment to secure world. Or something else > we don't have yet an idea. > > Let's say there is one board with two eMMCs. This board is used by two > OEMs. One is fine with all eMMCs in non-secure world, the other wants to > assign the eMMC to secure world. > > That's something that is related to inter-firmware component communication > to be authoritative. > > We need to avoid "little arrangements between friends" that exist today, > where the Linux provided DT is pruned from the second eMMC to accommodate > the use case. We need to think the OS as "immutable" across platforms and > adapt to available hardware (not come with its own description of what the > board is). > > May be a hob would contain a DT overlay or ACPI equivalent that would do > the job. > > In that case we do not need SMC. > > What do you think of this use case? > > > > @Simon Glass <sjg(a)chromium.org> - Thanks for the pointer to bloblist. > I briefly reviewed and it seems like a good baseline for what we may be > looking for. > > > > That being said, I would say that there is some benefit in having some > kind of unique identifiers (e.g. UUID or some unique signature) so that we > can tie standardized data structures (based on some future TBD specs) to a > particular ID. For example, if the TPM driver in BL33 is looking for the > TPM structure in the HOB/BOB list, and may not care about the other data > blobs. The driver needs a way to identify and locate the blob it cares > about. > > > > I guess we can achieve this with the tag, but the problem with tag when > you have eco-system with a lot of parties doing parallel development, you > can end up with tag collisions and folks fighting about who has rights to > what tag values. We would need some official process for folks to register > tags for whatever new structures we define, or maybe some tag range for > vendor specific structures. This comes with a lot of pain and > bureaucracy. On the other hand, UUID has been a proven way to make it easy > to just define your own blobs with **either** standard or vendor specific > structures without worry of ID collisions between vendors. > > > > We can probably debate whether there is any value in GUID/UUID or not > during the call… but again, boblist seems like a reasonable starting point > as an alternative to HOB. > > > > Thanks, > > --Harb > > > > *From:* François Ozog <francois.ozog(a)linaro.org> > *Sent:* Tuesday, March 23, 2021 10:00 AM > *To:* François Ozog <francois.ozog(a)linaro.org>; Ron Minnich < > rminnich(a)google.com>; Paul Isaac's <paul.isaacs(a)linaro.org> > *Cc:* Simon Glass <sjg(a)chromium.org>; Harb Abdulhamid OS < > abdulhamid(a)os.amperecomputing.com>; Boot Architecture Mailman List < > boot-architecture(a)lists.linaro.org>; tf-a(a)lists.trustedfirmware.org > *Subject:* Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for > information passing between boot stages > > > > +Ron Minnich <rminnich(a)google.com> +Paul Isaac's <paul.isaacs(a)linaro.org> > > > > Adding Ron and Paul because I think this interface should be also > benefiting LinuxBoot efforts. > > > > On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A < > tf-a(a)lists.trustedfirmware.org> wrote: > > Hi, > > > > I propose we cover the topic at the next Trusted Substrate > <https://collaborate.linaro.org/display/TS/Trusted+Substrate+Home> zoom > call <https://linaro-org.zoom.us/j/94563644892> on April 8th 4pm CET. > > > > The agenda: > > ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, > S-EL2, SCP) to adapt hardware description to some runtime conditions. > > runtime conditions here relates to DRAM size and topology detection, > secure DRAM memory carvings, PSCI and SCMI interface publishing. > > > > For additional background on existing metadata: UEFI Platform > Initialization Specification Version 1.7 > <https://uefi.org/sites/default/files/resources/PI_Spec_1_7_final_Jan_2019.p…> > , 5.5 Resource Descriptor HOB > > Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. > > This HOB lacks memory NUMA attachment or something that could be related > to fill SRAT table for ACPI or relevant DT proximity domains. > > HOB is not consistent accros platforms: some platforms (Arm) lists memory > from the booting NUMA node, other platforms (x86) lists all memory from all > NUMA nodes. (At least this is the case on the two platforms I tested). > > > > There are two proposals to use memory structures from SPL/BLx up to the > handover function (as defined in the Device Tree technical report > <https://docs.google.com/document/d/1CLkhLRaz_zcCq44DLGmPZQFPbYHOC6nzPowaL0X…>) > which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or > EDK2. > > I would propose we also discuss possibility of FF-A interface to actually > query information or request actions to be done (this is a model actually > used in some SoCs with proprietary SMC calls). > > > > Requirements (to be validated): > > - ACPI and DT hardware descriptions. > > - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) > > - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, > TF-A/LinuxBoot) > > - at least allows complete DRAM description and "persistent" usage > (reserved areas for secure world or other usages) > > - support secure world device assignment > > > > Cheers > > > > FF > > > > > > On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg(a)chromium.org> wrote: > > Hi, > > Can I suggest using bloblist for this instead? It is lightweight, > easier to parse, doesn't have GUIDs and is already used within U-Boot > for passing info between SPL/U-Boot, etc. > > Docs here: > https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist > Header file describes the format: > https://github.com/u-boot/u-boot/blob/master/include/bloblist.h > > Full set of unit tests: > https://github.com/u-boot/u-boot/blob/master/test/bloblist.c > > Regards, > Simon > > On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog(a)linaro.org> > wrote: > > > > +Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org> > > > > standardization is very much welcomed here and need to accommodate a very > > diverse set of situations. > > For example, TEE OS may need to pass memory reservations to BL33 or > > "capture" a device for the secure world. > > > > I have observed a number of architectures: > > 1) pass information from BLx to BLy in the form of a specific object > > 2) BLx called by BLy by a platform specific SMC to get information > > 3) BLx called by BLy by a platform specific SMC to perform Device Tree > > fixups > > > > I also imagined a standardized "broadcast" FF-A call so that any firmware > > element can either provide information or "do something". > > > > My understanding of your proposal is about standardizing on architecture > 1) > > with the HOB format. > > > > The advantage of the HOB is simplicity but it may be difficult to > implement > > schemes such as pruning a DT because device assignment in the secure > world. > > > > In any case, it looks feasible to have TF-A and OP-TEE complement the > list > > of HOBs to pass information downstream (the bootflow). > > > > It would be good to start with building the comprehensive list of > > information that need to be conveyed between firmware elements: > > > > information. | authoritative entity | reporting entity | information > > exchanged: > > dram | TFA | TFA | > > <format to be detailed, NUMA topology to build the SRAT table or DT > > equivalent?> > > PSCI | SCP | TFA? | > > SCMI | SCP or TEE-OS | TFA? TEE-OS?| > > secure SRAM | TFA. | TFA. | > > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | > > other? | | > > | > > > > Cheers > > > > FF > > > > > > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < > > tf-a(a)lists.trustedfirmware.org> wrote: > > > > > Hello Folks, > > > > > > > > > > > > I'm emailing to start an open discussion about the adoption of a > concept > > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware > > > Framework Architecture (FFA). This is something that is a pretty major > > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s > > > designed to enable a broad range of highly configurable datacenter > > > platforms. > > > > > > > > > > > > > > > > > > What is a HOB (Background)? > > > > > > --------------------------- > > > > > > UEFI PI spec describes a particular definition for how HOB may be used > for > > > transitioning between the PEI and DXE boot phases, which is a good > > > reference point for this discussion, but not necessarily the exact > solution > > > appropriate for TF-A. > > > > > > > > > > > > A HOB is simply a dynamically generated data structure passed in > between > > > two boot phases. This is information that was obtained through > discovery > > > and needs to be passed forward to the next boot phase *once*, with no > API > > > needed to call back (e.g. no call back into previous firmware phase is > > > needed to fetch this information at run-time - it is simply passed one > time > > > during boot). > > > > > > > > > > > > There may be one or more HOBs passed in between boot phases. If there > are > > > more than one HOB that needs to be passed, this can be in a form of a > "HOB > > > table", which (for example) could be a UUID indexed array of pointers > to > > > HOB structures, used to locate a HOB of interest (based on UUID). In > such > > > cases, instead of passing a single HOB, the boot phases may rely on > passing > > > the pointer to the HOB table. > > > > > > > > > > > > This has been extremely useful concept to employ on highly configurable > > > systems that must rely on flexible discovery mechanisms to initialize > and > > > boot the system. This is especially helpful when you have multiple > > > > > > > > > > > > > > > > > > Why do we need HOBs in TF-A?: > > > > > > ----------------------------- > > > > > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC > in > > > a way that is SoC specific *but* platform agnostic. This means that a > > > single ARM SoC that a SiP may deliver to customers may provide a single > > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad > > > range of platform designs and configurations in order to boot a > platform > > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to > > > achieve this, the platform configuration must be *discovered* instead > of > > > statically compiled as it is today in TF-A via device tree based > > > enumeration. The mechanisms of discovery may differ broadly depending > on > > > the relevant industry standard, or in some cases may have rely on SiP > > > specific discovery flows. > > > > > > > > > > > > For example: On server systems that support a broad range DIMM memory > > > population/topologies, all the necessary information required to boot > is > > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over > an > > > I2C bus. Leveraging the SPD bus, may platform variants could be > supported > > > with a single TF-A binary. Not only is this information required to > > > initialize memory in early boot phases (e.g. BL2), the subsequent boot > > > phases will also need this SPD info to construct a system physical > address > > > map and properly initialize the MMU based on the memory present, and > where > > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) > may > > > need to generate standard firmware tables to the operating systems, > such as > > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. > SLIT, > > > SRAT, even NFIT if NVDIMM's are present). > > > > > > > > > > > > In short, it all starts with a standardized or vendor specific > discovery > > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of > > > information to the next boot stages (e.g. BL31/BL32/BL33). > > > > > > > > > > > > Today, every HOB may be a vendor specific structure, but in the future > > > there may be benefit of defining standard HOBs. This may be useful for > > > memory discovery, passing the system physical address map, enabling TPM > > > measured boot, and potentially many other common HOB use-cases. > > > > > > > > > > > > It would be extremely beneficial to the datacenter market segment if > the > > > TF-A community would adopt this concept of information passing between > all > > > boot phases as opposed to rely solely on device tree enumeration. > This is > > > not intended to replace device tree, rather intended as an alternative > way > > > to describe the info that must be discovered and dynamically generated. > > > > > > > > > > > > > > > > > > Conclusion: > > > > > > ----------- > > > > > > We are proposing that the TF-A community begin pursuing the adoption of > > > HOBs as a mechanism used for information exchange between each boot > stage > > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we > > > want to explore standardizing some HOB structures for the BL33 phase > (e.g. > > > UEFI HOB structures), but initially would like to agree on this being a > > > useful mechanism used to pass information between each boot stage. > > > > > > > > > > > > Thanks, > > > > > > --Harb > > > > > > > > > > > > > > > > > > > > > -- > > > TF-A mailing list > > > TF-A(a)lists.trustedfirmware.org > > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > > > > > > > > > -- > > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* > > T: +33.67221.6485 > > francois.ozog(a)linaro.org | Skype: ffozog > > _______________________________________________ > > boot-architecture mailing list > > boot-architecture(a)lists.linaro.org > > https://lists.linaro.org/mailman/listinfo/boot-architecture > > > > > -- > > [image: Image removed by sender.] > > *François-Frédéric Ozog* | *Director Linaro Edge & Fog Computing Group* > > T: +33.67221.6485 > francois.ozog(a)linaro.org | Skype: ffozog > > > > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > > > > > -- > > [image: Image removed by sender.] > > *François-Frédéric Ozog* | *Director Linaro Edge & Fog Computing Group* > > T: +33.67221.6485 > francois.ozog(a)linaro.org | Skype: ffozog > > > > > > > -- > > [image: Image removed by sender.] > > *François-Frédéric Ozog* | *Director Linaro Edge & Fog Computing Group* > > T: +33.67221.6485 > francois.ozog(a)linaro.org | Skype: ffozog > > > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > -- [image: Linaro] <http://www.linaro.org/> *Bill Fletcher* | *Field Engineering* T: +44 7833 498336 <+44+7833+498336> bill.fletcher(a)linaro.org | Skype: billfletcher2020

3 years, 9 months

Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

by Joanna Farley

Hi Harb and others, This thread is now multi-mailing list and I can see some broader needs and opinions on aspects not directly defined by the TF-A project such as differing information exchange formats. However, this is definitely something the TF-A project can try and help provide enablement for to help with the goal of supplying support for single or common TF-A binaries builds for different images. TF-A already have some limited support in this space and are considering how this can be extended given some of the needs expressed here. Folks on the TF-A project are studying the below and will propose soon some ideas on how TF-A could provide more versatile enablement in this space shortly. Thanks Joanna From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> on behalf of François Ozog via TF-A <tf-a(a)lists.trustedfirmware.org> Reply to: François Ozog <francois.ozog(a)linaro.org> Date: Wednesday, 24 March 2021 at 08:34 To: Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com> Cc: "tf-a(a)lists.trustedfirmware.org" <tf-a(a)lists.trustedfirmware.org>, Simon Glass <sjg(a)chromium.org>, Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org>, Paul Isaac's <paul.isaacs(a)linaro.org>, Ron Minnich <rminnich(a)google.com> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages On Tue, 23 Mar 2021 at 23:39, Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com<mailto:abdulhamid@os.amperecomputing.com>> wrote: Hello Folks, Appreciate the feedback and replies on this. Glad to see that there is interest in this topic. 😊 I try to address the comments/feedback from Francois and Simon below…. @François Ozog<mailto:francois.ozog@linaro.org> – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT. Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases. The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM). Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model: 1. “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances 2. “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances. Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code. To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software. I understand the versatility of DT, but I see two major problems with DT: * DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained. * DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob) I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs). Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls. Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call. I am not tied to a particular data representation and using SMC to just pass data structures is overkill as you say. The SMC model seems useful to do complex things like device assignment to secure world. Or something else we don't have yet an idea. Let's say there is one board with two eMMCs. This board is used by two OEMs. One is fine with all eMMCs in non-secure world, the other wants to assign the eMMC to secure world. That's something that is related to inter-firmware component communication to be authoritative. We need to avoid "little arrangements between friends" that exist today, where the Linux provided DT is pruned from the second eMMC to accommodate the use case. We need to think the OS as "immutable" across platforms and adapt to available hardware (not come with its own description of what the board is). May be a hob would contain a DT overlay or ACPI equivalent that would do the job. In that case we do not need SMC. What do you think of this use case? @Simon Glass<mailto:sjg@chromium.org> - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for. That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about. I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors. We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB. Thanks, --Harb From: François Ozog <francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org>> Sent: Tuesday, March 23, 2021 10:00 AM To: François Ozog <francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org>>; Ron Minnich <rminnich(a)google.com<mailto:rminnich@google.com>>; Paul Isaac's <paul.isaacs(a)linaro.org<mailto:paul.isaacs@linaro.org>> Cc: Simon Glass <sjg(a)chromium.org<mailto:sjg@chromium.org>>; Harb Abdulhamid OS <abdulhamid(a)os.amperecomputing.com<mailto:abdulhamid@os.amperecomputing.com>>; Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org<mailto:boot-architecture@lists.linaro.org>>; tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages +Ron Minnich<mailto:rminnich@google.com> +Paul Isaac's<mailto:paul.isaacs@linaro.org> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts. On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A <tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>> wrote: Hi, I propose we cover the topic at the next Trusted Substrate<https://collaborate.linaro.org/display/TS/Trusted+Substrate+Home> zoom call<https://linaro-org.zoom.us/j/94563644892> on April 8th 4pm CET. The agenda: ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions. runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing. For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7<https://uefi.org/sites/default/files/resources/PI_Spec_1_7_final_Jan_2019.p…>, 5.5 Resource Descriptor HOB Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains. HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested). There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report<https://docs.google.com/document/d/1CLkhLRaz_zcCq44DLGmPZQFPbYHOC6nzPowaL0X…>) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2. I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls). Requirements (to be validated): - ACPI and DT hardware descriptions. - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot) - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages) - support secure world device assignment Cheers FF On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg(a)chromium.org<mailto:sjg@chromium.org>> wrote: Hi, Can I suggest using bloblist for this instead? It is lightweight, easier to parse, doesn't have GUIDs and is already used within U-Boot for passing info between SPL/U-Boot, etc. Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist Header file describes the format: https://github.com/u-boot/u-boot/blob/master/include/bloblist.h Full set of unit tests: https://github.com/u-boot/u-boot/blob/master/test/bloblist.c Regards, Simon On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org>> wrote: > > +Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org<mailto:boot-architecture@lists.linaro.org>> > > standardization is very much welcomed here and need to accommodate a very > diverse set of situations. > For example, TEE OS may need to pass memory reservations to BL33 or > "capture" a device for the secure world. > > I have observed a number of architectures: > 1) pass information from BLx to BLy in the form of a specific object > 2) BLx called by BLy by a platform specific SMC to get information > 3) BLx called by BLy by a platform specific SMC to perform Device Tree > fixups > > I also imagined a standardized "broadcast" FF-A call so that any firmware > element can either provide information or "do something". > > My understanding of your proposal is about standardizing on architecture 1) > with the HOB format. > > The advantage of the HOB is simplicity but it may be difficult to implement > schemes such as pruning a DT because device assignment in the secure world. > > In any case, it looks feasible to have TF-A and OP-TEE complement the list > of HOBs to pass information downstream (the bootflow). > > It would be good to start with building the comprehensive list of > information that need to be conveyed between firmware elements: > > information. | authoritative entity | reporting entity | information > exchanged: > dram | TFA | TFA | > <format to be detailed, NUMA topology to build the SRAT table or DT > equivalent?> > PSCI | SCP | TFA? | > SCMI | SCP or TEE-OS | TFA? TEE-OS?| > secure SRAM | TFA. | TFA. | > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | > other? | | > | > > Cheers > > FF > > > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < > tf-a(a)lists.trustedfirmware.org<mailto:tf-a@lists.trustedfirmware.org>> wrote: > > > Hello Folks, > > > > > > > > I'm emailing to start an open discussion about the adoption of a concept > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware > > Framework Architecture (FFA). This is something that is a pretty major > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s > > designed to enable a broad range of highly configurable datacenter > > platforms. > > > > > > > > > > > > What is a HOB (Background)? > > > > --------------------------- > > > > UEFI PI spec describes a particular definition for how HOB may be used for > > transitioning between the PEI and DXE boot phases, which is a good > > reference point for this discussion, but not necessarily the exact solution > > appropriate for TF-A. > > > > > > > > A HOB is simply a dynamically generated data structure passed in between > > two boot phases. This is information that was obtained through discovery > > and needs to be passed forward to the next boot phase *once*, with no API > > needed to call back (e.g. no call back into previous firmware phase is > > needed to fetch this information at run-time - it is simply passed one time > > during boot). > > > > > > > > There may be one or more HOBs passed in between boot phases. If there are > > more than one HOB that needs to be passed, this can be in a form of a "HOB > > table", which (for example) could be a UUID indexed array of pointers to > > HOB structures, used to locate a HOB of interest (based on UUID). In such > > cases, instead of passing a single HOB, the boot phases may rely on passing > > the pointer to the HOB table. > > > > > > > > This has been extremely useful concept to employ on highly configurable > > systems that must rely on flexible discovery mechanisms to initialize and > > boot the system. This is especially helpful when you have multiple > > > > > > > > > > > > Why do we need HOBs in TF-A?: > > > > ----------------------------- > > > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in > > a way that is SoC specific *but* platform agnostic. This means that a > > single ARM SoC that a SiP may deliver to customers may provide a single > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad > > range of platform designs and configurations in order to boot a platform > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to > > achieve this, the platform configuration must be *discovered* instead of > > statically compiled as it is today in TF-A via device tree based > > enumeration. The mechanisms of discovery may differ broadly depending on > > the relevant industry standard, or in some cases may have rely on SiP > > specific discovery flows. > > > > > > > > For example: On server systems that support a broad range DIMM memory > > population/topologies, all the necessary information required to boot is > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an > > I2C bus. Leveraging the SPD bus, may platform variants could be supported > > with a single TF-A binary. Not only is this information required to > > initialize memory in early boot phases (e.g. BL2), the subsequent boot > > phases will also need this SPD info to construct a system physical address > > map and properly initialize the MMU based on the memory present, and where > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may > > need to generate standard firmware tables to the operating systems, such as > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT, > > SRAT, even NFIT if NVDIMM's are present). > > > > > > > > In short, it all starts with a standardized or vendor specific discovery > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of > > information to the next boot stages (e.g. BL31/BL32/BL33). > > > > > > > > Today, every HOB may be a vendor specific structure, but in the future > > there may be benefit of defining standard HOBs. This may be useful for > > memory discovery, passing the system physical address map, enabling TPM > > measured boot, and potentially many other common HOB use-cases. > > > > > > > > It would be extremely beneficial to the datacenter market segment if the > > TF-A community would adopt this concept of information passing between all > > boot phases as opposed to rely solely on device tree enumeration. This is > > not intended to replace device tree, rather intended as an alternative way > > to describe the info that must be discovered and dynamically generated. > > > > > > > > > > > > Conclusion: > > > > ----------- > > > > We are proposing that the TF-A community begin pursuing the adoption of > > HOBs as a mechanism used for information exchange between each boot stage > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we > > want to explore standardizing some HOB structures for the BL33 phase (e.g. > > UEFI HOB structures), but initially would like to agree on this being a > > useful mechanism used to pass information between each boot stage. > > > > > > > > Thanks, > > > > --Harb > > > > > > > > > > > > > > -- > > TF-A mailing list > > TF-A(a)lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmware.org> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > > > > > -- > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* > T: +33.67221.6485 > francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org> | Skype: ffozog > _______________________________________________ > boot-architecture mailing list > boot-architecture(a)lists.linaro.org<mailto:boot-architecture@lists.linaro.org> > https://lists.linaro.org/mailman/listinfo/boot-architecture -- [Image removed by sender.] François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group T: +33.67221.6485 francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org> | Skype: ffozog -- TF-A mailing list TF-A(a)lists.trustedfirmware.org<mailto:TF-A@lists.trustedfirmware.org> https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- [Image removed by sender.] François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group T: +33.67221.6485 francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org> | Skype: ffozog -- [Image removed by sender.] François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group T: +33.67221.6485 francois.ozog(a)linaro.org<mailto:francois.ozog@linaro.org> | Skype: ffozog

3 years, 9 months

Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

by François Ozog

+Boot Architecture Mailman List <boot-architecture(a)lists.linaro.org> standardization is very much welcomed here and need to accommodate a very diverse set of situations. For example, TEE OS may need to pass memory reservations to BL33 or "capture" a device for the secure world. I have observed a number of architectures: 1) pass information from BLx to BLy in the form of a specific object 2) BLx called by BLy by a platform specific SMC to get information 3) BLx called by BLy by a platform specific SMC to perform Device Tree fixups I also imagined a standardized "broadcast" FF-A call so that any firmware element can either provide information or "do something". My understanding of your proposal is about standardizing on architecture 1) with the HOB format. The advantage of the HOB is simplicity but it may be difficult to implement schemes such as pruning a DT because device assignment in the secure world. In any case, it looks feasible to have TF-A and OP-TEE complement the list of HOBs to pass information downstream (the bootflow). It would be good to start with building the comprehensive list of information that need to be conveyed between firmware elements: information. | authoritative entity | reporting entity | information exchanged: dram | TFA | TFA | <format to be detailed, NUMA topology to build the SRAT table or DT equivalent?> PSCI | SCP | TFA? | SCMI | SCP or TEE-OS | TFA? TEE-OS?| secure SRAM | TFA. | TFA. | secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | other? | | | Cheers FF On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < tf-a(a)lists.trustedfirmware.org> wrote: > Hello Folks, > > > > I'm emailing to start an open discussion about the adoption of a concept > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware > Framework Architecture (FFA). This is something that is a pretty major > pain point when it comes to the adoption of TF-A in ARM Server SoC’s > designed to enable a broad range of highly configurable datacenter > platforms. > > > > > > What is a HOB (Background)? > > --------------------------- > > UEFI PI spec describes a particular definition for how HOB may be used for > transitioning between the PEI and DXE boot phases, which is a good > reference point for this discussion, but not necessarily the exact solution > appropriate for TF-A. > > > > A HOB is simply a dynamically generated data structure passed in between > two boot phases. This is information that was obtained through discovery > and needs to be passed forward to the next boot phase *once*, with no API > needed to call back (e.g. no call back into previous firmware phase is > needed to fetch this information at run-time - it is simply passed one time > during boot). > > > > There may be one or more HOBs passed in between boot phases. If there are > more than one HOB that needs to be passed, this can be in a form of a "HOB > table", which (for example) could be a UUID indexed array of pointers to > HOB structures, used to locate a HOB of interest (based on UUID). In such > cases, instead of passing a single HOB, the boot phases may rely on passing > the pointer to the HOB table. > > > > This has been extremely useful concept to employ on highly configurable > systems that must rely on flexible discovery mechanisms to initialize and > boot the system. This is especially helpful when you have multiple > > > > > > Why do we need HOBs in TF-A?: > > ----------------------------- > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in > a way that is SoC specific *but* platform agnostic. This means that a > single ARM SoC that a SiP may deliver to customers may provide a single > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad > range of platform designs and configurations in order to boot a platform > specific firmware (e.g. BL33 and possibly even BL32 code). In order to > achieve this, the platform configuration must be *discovered* instead of > statically compiled as it is today in TF-A via device tree based > enumeration. The mechanisms of discovery may differ broadly depending on > the relevant industry standard, or in some cases may have rely on SiP > specific discovery flows. > > > > For example: On server systems that support a broad range DIMM memory > population/topologies, all the necessary information required to boot is > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an > I2C bus. Leveraging the SPD bus, may platform variants could be supported > with a single TF-A binary. Not only is this information required to > initialize memory in early boot phases (e.g. BL2), the subsequent boot > phases will also need this SPD info to construct a system physical address > map and properly initialize the MMU based on the memory present, and where > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may > need to generate standard firmware tables to the operating systems, such as > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT, > SRAT, even NFIT if NVDIMM's are present). > > > > In short, it all starts with a standardized or vendor specific discovery > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of > information to the next boot stages (e.g. BL31/BL32/BL33). > > > > Today, every HOB may be a vendor specific structure, but in the future > there may be benefit of defining standard HOBs. This may be useful for > memory discovery, passing the system physical address map, enabling TPM > measured boot, and potentially many other common HOB use-cases. > > > > It would be extremely beneficial to the datacenter market segment if the > TF-A community would adopt this concept of information passing between all > boot phases as opposed to rely solely on device tree enumeration. This is > not intended to replace device tree, rather intended as an alternative way > to describe the info that must be discovered and dynamically generated. > > > > > > Conclusion: > > ----------- > > We are proposing that the TF-A community begin pursuing the adoption of > HOBs as a mechanism used for information exchange between each boot stage > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we > want to explore standardizing some HOB structures for the BL33 phase (e.g. > UEFI HOB structures), but initially would like to agree on this being a > useful mechanism used to pass information between each boot stage. > > > > Thanks, > > --Harb > > > > > > > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > -- François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* T: +33.67221.6485 francois.ozog(a)linaro.org | Skype: ffozog

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boot-architecture March 2021