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[vmsg][RFC V2 PATCH 0/6] virtio: Add support for Virtio message transport

by Viresh Kumar

Hello, I will try to send this upstream early next week. V2: - Don't limit get/set config to 8 bytes only. - Improved direct/indirect message handling. - Take care of EBUSY error during indirect message. - Static assertions. -------------------------8<------------------------- Hello, This RFC series introduces support for a new Virtio transport type: "virtio-msg", as proposed in [1]. Unlike existing transport types like virtio-mmio or virtio-pci which rely on memory-mapped registers, virtio-msg implements transport operations via structured messages. Those messages can be transported through different mechanisms such as mailboxes, shared memory based FIFO or specific protocols such as FF-A on Arm. This series includes: - Core virtio-msg transport support. - Two message transport bus implementations: - virtio-msg-ffa: based on ARM's Firmware Framework for Arm (FF-A). - virtio-msg-loopback: a loopback device for testing and validation. The code is available here for reference: [3] and virtio-msg loopback test setup is explained here: [2]. This series is based on v6.16-rc6 and depends on commit [4] from linux-next. ### Memory Mapping and Reserved Memory Usage The first two patches enhance the reserved-memory subsystem to support attaching struct device`s that do not originate from DT nodes—essential for virtual or dynamically discovered devices like the FF-A or loopback buses. This reserved-memory region enables: - Restricting all DMA-coherent and streaming DMA memory to a controlled range. - Allowing the remote endpoint to pre-map this memory, reducing runtime overhead. - Preventing unintentional data leaks, since memory is typically shared at page granularity. - For the loopback bus, it restricts the portion of kernel memory that can be mapped into userspace, improving safety. Device association with reserved-memory regions is based on DT node naming conventions, such as vmsglb@ or vmsgffa@, similar to the remoteproc framework’s approach. Feedback on the design, API, and approach is welcome. -- Viresh [1] https://lore.kernel.org/all/20250620224426.3923880-2-bill.mills@linaro.org/ [2] https://linaro.atlassian.net/wiki/spaces/HVAC/pages/30104092673 [3] git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git virtio/msg-rfc-v1 [4] From linux-next: 5be53630b4f0 virtio-mmio: Remove virtqueue list from mmio device Viresh Kumar (6): of: reserved-memory: Add reserved_mem_device_init() of: reserved-memory: Add of_reserved_mem_lookup_by_name virtio: Add support for virtio-msg transport virtio-msg: Add optional userspace interface for message I/O virtio-msg: Add support for FF-A (Firmware Framework for Arm) bus virtio-msg: Add support for loopback bus MAINTAINERS | 7 + drivers/of/of_reserved_mem.c | 91 ++-- drivers/virtio/Kconfig | 34 ++ drivers/virtio/Makefile | 5 + drivers/virtio/virtio_msg.c | 611 +++++++++++++++++++++++++++ drivers/virtio/virtio_msg.h | 88 ++++ drivers/virtio/virtio_msg_ffa.c | 505 ++++++++++++++++++++++ drivers/virtio/virtio_msg_loopback.c | 323 ++++++++++++++ drivers/virtio/virtio_msg_user.c | 119 ++++++ include/linux/of_reserved_mem.h | 13 + include/uapi/linux/virtio_msg.h | 221 ++++++++++ include/uapi/linux/virtio_msg_ffa.h | 94 +++++ include/uapi/linux/virtio_msg_lb.h | 22 + 13 files changed, 2109 insertions(+), 24 deletions(-) create mode 100644 drivers/virtio/virtio_msg.c create mode 100644 drivers/virtio/virtio_msg.h create mode 100644 drivers/virtio/virtio_msg_ffa.c create mode 100644 drivers/virtio/virtio_msg_loopback.c create mode 100644 drivers/virtio/virtio_msg_user.c create mode 100644 include/uapi/linux/virtio_msg.h create mode 100644 include/uapi/linux/virtio_msg_ffa.h create mode 100644 include/uapi/linux/virtio_msg_lb.h -- 2.31.1.272.g89b43f80a514

2 months, 3 weeks

4
14
0 0

Release v0.6 of hvac-demo

by Bill Mills

All, I have pushed and tagged a new version of the hvac-demo repo. I have also updated the pre-built container image at: docker.io/wmills/hvac-demo Remember you may need to pull the container image again to see the new version: podman pull docker.io/wmills/hvac-demo - or - docker pull docker.io/wmills/hvac-demo Changes include: * added demo-loopback to show virtio-msg-loopback (based on Viresh's work) * added demo-amp-qemu-pci with virtio-msg-amp on an emulated pcie card in QEMU * renamed all the demos to describe the demo instead of numbers * rebased demo-ffa-xen to use Viresh's latest kernel and rust code * other demos are just renamed Old name New name ---------------------------------- new demo-loopback new demo-amp-qemu-pci demo1 demoo-ffa-xen demo2a (deleted) demo2b demo-proxy-qemu demo3 demo-amp-zephyr demo4 demo-amp-dual-linux The following issues are known: 1) demo-ffa-xen hangs or crashes 1 out of 5 or 10 times Just run again if you see this 2) ./Build all does not build linux-virtio-msg-v2, use ./Build all linux-virtio-msg-amp-v2 You do not need to build the demos to run them 3) The timeout in demo-amp-dual-linux to too short for VERY slow systems Most people won't see this issue. I was testing on a RPiv5 Fixes for the last two issues are in the wip-v0.6-fixes branch. -- Bill Mills Principal Technical Consultant, Linaro +1-240-643-0836 TZ: US Eastern Work Schedule: Tues/Wed/Thur

4 months, 2 weeks

1
0
0 0

[RFC PATCH 0/6] virtio: Add support for Virtio message transport

by Viresh Kumar

Hello, This RFC series introduces support for a new Virtio transport type: "virtio-msg", as proposed in [1]. Unlike existing transport types like virtio-mmio or virtio-pci, which rely on memory-mapped registers, virtio-msg implements transport operations via structured messages. Those messages can be transported through different mechanisms such as mailboxes, shared memory based FIFO or specific protocols such as FF-A on Arm. This series includes: - Core virtio-msg transport support. - Two message transport bus implementations: - virtio-msg-ffa: based on ARM's Firmware Framework for Arm (FF-A). - virtio-msg-loopback: a loopback device for testing and validation. The code is available here for reference: [2] and virtio-msg loopback and FF-A test setups are explained here: [3] and [4]. This series is based on v6.16 and depends on commit [5]. ### Memory Mapping and Reserved Memory Usage The first two patches enhance the reserved-memory subsystem to support attaching struct device`s that do not originate from DT nodes — essential for virtual or dynamically discovered devices like the FF-A or loopback buses. This reserved-memory region enables: - Restricting all DMA-coherent and streaming DMA memory to a controlled range. - Allowing the remote endpoint to pre-map this memory, reducing runtime overhead. - Preventing unintentional data leaks, since memory is typically shared at page granularity. - For the loopback bus, it restricts the portion of kernel memory that can be mapped into userspace, improving safety. Device association with reserved-memory regions is based on DT node naming conventions, such as vmsglb@ or vmsgffa@, similar to the remoteproc framework’s approach. Feedback on the design, API, and approach is welcome. -- Viresh [1] https://lore.kernel.org/all/20250620224426.3923880-2-bill.mills@linaro.org/ [2] git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git virtio/msg-rfc-v1 [3] https://linaro.atlassian.net/wiki/spaces/HVAC/pages/30104092673 [4] https://linaro.atlassian.net/wiki/spaces/HVAC/pages/29657792513 [5] From linux-next: 5be53630b4f0 virtio-mmio: Remove virtqueue list from mmio device Viresh Kumar (6): of: reserved-memory: Add reserved_mem_device_init() of: reserved-memory: Add of_reserved_mem_lookup_by_name virtio: Add support for virtio-msg transport virtio-msg: Add optional userspace interface for message I/O virtio-msg: Add support for FF-A (Firmware Framework for Arm) bus virtio-msg: Add support for loopback bus MAINTAINERS | 7 + drivers/of/of_reserved_mem.c | 91 +++- drivers/virtio/Kconfig | 34 ++ drivers/virtio/Makefile | 5 + drivers/virtio/virtio_msg.c | 655 +++++++++++++++++++++++++++ drivers/virtio/virtio_msg_ffa.c | 505 +++++++++++++++++++++ drivers/virtio/virtio_msg_internal.h | 88 ++++ drivers/virtio/virtio_msg_loopback.c | 323 +++++++++++++ drivers/virtio/virtio_msg_user.c | 140 ++++++ include/linux/of_reserved_mem.h | 13 + include/uapi/linux/virtio_msg.h | 213 +++++++++ include/uapi/linux/virtio_msg_ffa.h | 94 ++++ include/uapi/linux/virtio_msg_lb.h | 22 + 13 files changed, 2166 insertions(+), 24 deletions(-) create mode 100644 drivers/virtio/virtio_msg.c create mode 100644 drivers/virtio/virtio_msg_ffa.c create mode 100644 drivers/virtio/virtio_msg_internal.h create mode 100644 drivers/virtio/virtio_msg_loopback.c create mode 100644 drivers/virtio/virtio_msg_user.c create mode 100644 include/uapi/linux/virtio_msg.h create mode 100644 include/uapi/linux/virtio_msg_ffa.h create mode 100644 include/uapi/linux/virtio_msg_lb.h -- 2.31.1.272.g89b43f80a514

4 months, 3 weeks

1
6
0 0

[RFC PATCH 0/6] virtio: Add support for Virtio message transport

by Viresh Kumar

Hi everyone, Over the last few weeks, I have made numerous changes in the design and code to get it ready for mainline. I have now prepared the initial RFC patchset to be sent to LKML. Please have a look and provide your valuable feedback. -------------------------8<------------------------- Hello, This RFC series introduces support for a new Virtio transport type: "virtio-msg", as proposed in [1]. Unlike existing transport types like virtio-mmio or virtio-pci which rely on memory-mapped registers, virtio-msg implements transport operations via structured message exchanges using standard virtqueues. This series includes: - Core virtio-msg transport support. - Two message transport bus implementations: - virtio-msg-ffa: based on ARM's Firmware Framework for Arm (FF-A). - virtio-msg-loopback: a loopback device for testing and validation. The code is available here for reference: [3] and virtio-msg loopback test setup is explained here: [2]. This series is based on v6.16-rc6 and depends on commit [4] from linux-next. ### Memory Mapping and Reserved Memory Usage The first two patches enhance the reserved-memory subsystem to support attaching `struct device`s that do not originate from DT nodes—essential for virtual or dynamically discovered devices like the FF-A or loopback buses. This reserved-memory region enables: - Restricting all DMA-coherent and streaming DMA memory to a controlled range. - Allowing the remote endpoint to pre-map this memory, reducing runtime overhead. - Preventing unintentional data leaks, since memory is typically shared at page granularity. - For the loopback bus, it restricts the portion of kernel memory that can be mapped into userspace, improving safety. Feedback on the design, API, and approach is welcome. -- Viresh [1] https://lore.kernel.org/all/20250620224426.3923880-2-bill.mills@linaro.org/ [2] https://linaro.atlassian.net/wiki/spaces/HVAC/pages/30104092673 [3] git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git virtio/msg-rfc-v1 [4] From linux-next: 5be53630b4f0 virtio-mmio: Remove virtqueue list from mmio device Viresh Kumar (6): of: reserved-memory: Add reserved_mem_device_init() of: reserved-memory: Add of_reserved_mem_lookup_by_name virtio: Add support for virtio-msg transport virtio-msg: Add optional userspace interface for message I/O virtio-msg: Add support for FF-A (Firmware Framework for Arm) bus virtio-msg: Add support for loopback bus MAINTAINERS | 7 + drivers/of/of_reserved_mem.c | 91 +++-- drivers/virtio/Kconfig | 34 ++ drivers/virtio/Makefile | 5 + drivers/virtio/virtio_msg.c | 546 +++++++++++++++++++++++++++ drivers/virtio/virtio_msg.h | 88 +++++ drivers/virtio/virtio_msg_ffa.c | 501 ++++++++++++++++++++++++ drivers/virtio/virtio_msg_loopback.c | 323 ++++++++++++++++ drivers/virtio/virtio_msg_user.c | 119 ++++++ include/linux/of_reserved_mem.h | 13 + include/uapi/linux/virtio_msg.h | 221 +++++++++++ include/uapi/linux/virtio_msg_ffa.h | 94 +++++ include/uapi/linux/virtio_msg_lb.h | 22 ++ 13 files changed, 2040 insertions(+), 24 deletions(-) create mode 100644 drivers/virtio/virtio_msg.c create mode 100644 drivers/virtio/virtio_msg.h create mode 100644 drivers/virtio/virtio_msg_ffa.c create mode 100644 drivers/virtio/virtio_msg_loopback.c create mode 100644 drivers/virtio/virtio_msg_user.c create mode 100644 include/uapi/linux/virtio_msg.h create mode 100644 include/uapi/linux/virtio_msg_ffa.h create mode 100644 include/uapi/linux/virtio_msg_lb.h -- 2.31.1.272.g89b43f80a514

5 months

3
20
0 0

Virtio message loopback

by Viresh Kumar

Hello, As discussed yesterday during the call, I have prepared the list of instructions to reproduce my virtio-msg loopback setup. Please give a try and lemme know if something doesn't work. This is based on the latest version of the spec (from Bill's latest pull request today). -- Viresh [1] https://linaro.atlassian.net/wiki/spaces/HVAC/pages/30104092673 -- viresh

5 months, 3 weeks

2
2
0 0

[PATCH RFC v2 0/1] virtio-msg transport layer

by Bill Mills

This series adds the virtio-msg transport layer. The individuals and organizations involved in this effort have had difficulty in using the existing virtio-transports in various situations and desire to add one more transport that performs its transport layer operations by sending and receiving messages. Implementations of virtio-msg will normally be done in multiple layers: * common / device level * bus level The common / device level defines the messages exchanged between the driver and a device. This common part should lead to a common driver holding most of the virtio specifics and can be shared by all virtio-msg bus implementations. The kernel implementation in [3] shows this separation. As with other transport layers, virtio-msg should not require modifications to existing virtio device implementations (virtio-net, virtio-blk etc). The common / device level is the main focus of this version of the patch series. The virtio-msg bus level implements the normal things a bus defines (enumeration, dma operations, etc) but also implements the message send and receive operations. A number of bus implementations are envisioned, some of which will be reusable and general purpose. Other bus implementations might be unique to a given situation, for example only used by a PCIe card and its driver. How much of the bus level should be described in the virtio spec is one item we wish to discuss. This draft takes a middle approach by describing the bus level and defining some standard bus level messages that MAY be used by the bus. It also describes a range of bus messages that are implementation dependent. The standard bus messages are an effort to avoid different bus implementations doing the same thing in different ways for no good reason. However the different environments will require different things. Instead of trying to anticipate all needs and provide something very abstract, we think implementation specific messages will be needed at the bus level. Over time, if we see similar messages across multiple bus implementations, we will move to standardize a bus level message for that. We are working on two reusable bus implementations: * virtio-msg-ffa based on Arm FF-A interface for use between: * normal world and secure world * host and VM or VM to VM * Can be used w/ or with out a hypervisor * Any Hypervisor that implements FF-A can be used * virtio-msg-amp for use between heterogenous systems * The main processors and its co-processors on an AMP SOC * Two or more systems connected via PCIe * Minimal requirements: bi-directional interrupts and at least one shared memory area We also anticipate a few more: * virtio-msg-xen specific to Xen * Usable on any Xen system (including x86 where FF-A does not exist) * Using Xen events and page grants * virtio-msg-loopback for userspace implemented devices * Allows user space to provide devices to its own kernel * This is similar to fuse, cuse or loopback block devices but for virtio * Once developed this can provide a single kernel demo of virtio-msg * [Work has begun on this] * virtio-msg over admin virtqueues * This allows any virtio-pci device that supports admin virtqueues to also support a virtio-msg bus that supports sub devices * [We are looking for collaborators for this work] Changes since RFC1: * reformated document to better conform to the virtio spec style - created an introduction chapter - created a basic concept chapter - created bus operation and device initialization and operation chapters - reworked description of transport and bus messages - attempted a "compliance chapter" - reused spec macros - switched to MAY/MUST/SHALL/SHOULD wording - eliminate the use of terms front-end and back-end and use driver and device * made the maximum message size variable per bus instance * use "device number" for virtio-msg device instances on the bus instead of adding yet another meaning for "device ID" * added the configuration generation count and its use * described types of things that can be done with bus specific messages such as setup of bus level shared memory and out of band notifications * removed wording of notification being optional at transport level and described bus level notifications of in-band, out-of-band, and polled from driver side bus * removed the ERROR message from transport level. Errors should be handled at the bus level to better match virtio-pci and virtio-mmio * removed bus level reset and status from standard bus messages * replaced bus messages DEVICE_{ADDED,REMOVED} with EVENT_DEVICE * changed names to GET_DEVICE_FEATURES and SET_DRIVER_FEATURES for clarity * made SET_DEVICE_STATE return new state as it may not match * Don't echo back the data in SET_VQUEUE (it cannot change) * defined request/response vs event message id ranges * match field size of next offset and wrap to virtio-{pci,mmio} * added maximum number of virtqueues to DEVICE_INFO * added admin virtqueue and SHM support This series is a work in progress and we acknowledge at least the following issues we need to work on: * Better conformance documentation * Publish an update to Arm FF-A spec that shows virtio-msg binding (work underway) * Publish virtio-msg-amp data structures and messages somewhere * Align implementations to this version and send PATCH v1 (non-rfc) Background info and work in progress implementations: * HVAC project page with intro slides [1] * HVAC demo repo w/ instructions in README.md [2] * Kernel w/ virtio-msg common level and ffa support [3] * QEMU w/ support for one form of virtio-msg-amp [4] * Portable RTOS library w/ one form of virtio-msg-amp [5] In addition to the QEMU system based demos in the hvac-demo repo, we also have two hardware systems running: * AMD x86 + AMD Arm Versal connected via PCIe * ST STM32MP157 A7 Linux using virtio-i2c provided by M4 Zephyr Please note that although the demos work, they are not yet aligned with each other nor this version of the spec. [1] https://linaro.atlassian.net/wiki/spaces/HVAC/overview [2] https://github.com/wmamills/hvac-demo [3] https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git/log/?h=vi… [4] https://github.com/edgarigl/qemu/commits/edgar/virtio-msg-new [5] https://github.com/arnopo/open-amp/commits/virtio-msg/ Bill Mills (1): virtio-msg: Add virtio-msg, a message based virtio transport layer content.tex | 1 + transport-msg.tex | 1354 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 1355 insertions(+) create mode 100644 transport-msg.tex -- 2.34.1

6 months

4
5
0 0

PR #20, fix-up pending changes before RFCv2

by Bill Mills

All, The pull request referenced here covers the remaining items needed before sending RFCv2. Please take a look and let me know if you see issues. You can comment in the PR or send email to the list. https://github.com/Linaro/virtio-msg-spec/pull/20 Thanks, Bill -- Bill Mills Principal Technical Consultant, Linaro +1-240-643-0836 TZ: US Eastern Work Schedule: Tues/Wed/Thur

6 months, 1 week

1
0
0 0

[PATCH] firmware: arm_ffa: Fix struct ffa_indirect_msg_hdr

by Viresh Kumar

As per the spec, one 32 bit reserved entry is missing here, add it. Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> --- include/linux/arm_ffa.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h index 5bded24dc24f..e1634897e159 100644 --- a/include/linux/arm_ffa.h +++ b/include/linux/arm_ffa.h @@ -283,6 +283,7 @@ struct ffa_indirect_msg_hdr { u32 offset; u32 send_recv_id; u32 size; + u32 res1; uuid_t uuid; }; -- 2.31.1.272.g89b43f80a514

6 months, 3 weeks

1
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0 0

[PATCH] virtio-mmio: Remove virtqueue list from mmio device

by Viresh Kumar

The MMIO transport implementation creates a list of virtqueues for a virtio device, while the same is already available in the struct virtio_device. Don't create a duplicate list, and use the other one instead. While at it, fix the virtio_device_for_each_vq() macro to accept an argument like "&vm_dev->vdev" (which currently fails to build). Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> --- I have tested this with a Xen/Qemu based setup to test guest to host virtio-i2c communication. Works fine, not sure why this code was added in the first place. drivers/virtio/virtio_mmio.c | 52 +++--------------------------------- include/linux/virtio.h | 2 +- 2 files changed, 4 insertions(+), 50 deletions(-) diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c index 5d78c2d572ab..b152a1eca05a 100644 --- a/drivers/virtio/virtio_mmio.c +++ b/drivers/virtio/virtio_mmio.c @@ -65,7 +65,6 @@ #include <linux/platform_device.h> #include <linux/pm.h> #include <linux/slab.h> -#include <linux/spinlock.h> #include <linux/virtio.h> #include <linux/virtio_config.h> #include <uapi/linux/virtio_mmio.h> @@ -88,22 +87,8 @@ struct virtio_mmio_device { void __iomem *base; unsigned long version; - - /* a list of queues so we can dispatch IRQs */ - spinlock_t lock; - struct list_head virtqueues; -}; - -struct virtio_mmio_vq_info { - /* the actual virtqueue */ - struct virtqueue *vq; - - /* the list node for the virtqueues list */ - struct list_head node; }; - - /* Configuration interface */ static u64 vm_get_features(struct virtio_device *vdev) @@ -300,9 +285,8 @@ static bool vm_notify_with_data(struct virtqueue *vq) static irqreturn_t vm_interrupt(int irq, void *opaque) { struct virtio_mmio_device *vm_dev = opaque; - struct virtio_mmio_vq_info *info; + struct virtqueue *vq; unsigned long status; - unsigned long flags; irqreturn_t ret = IRQ_NONE; /* Read and acknowledge interrupts */ @@ -315,10 +299,8 @@ static irqreturn_t vm_interrupt(int irq, void *opaque) } if (likely(status & VIRTIO_MMIO_INT_VRING)) { - spin_lock_irqsave(&vm_dev->lock, flags); - list_for_each_entry(info, &vm_dev->virtqueues, node) - ret |= vring_interrupt(irq, info->vq); - spin_unlock_irqrestore(&vm_dev->lock, flags); + virtio_device_for_each_vq(&vm_dev->vdev, vq) + ret |= vring_interrupt(irq, vq); } return ret; @@ -329,14 +311,8 @@ static irqreturn_t vm_interrupt(int irq, void *opaque) static void vm_del_vq(struct virtqueue *vq) { struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev); - struct virtio_mmio_vq_info *info = vq->priv; - unsigned long flags; unsigned int index = vq->index; - spin_lock_irqsave(&vm_dev->lock, flags); - list_del(&info->node); - spin_unlock_irqrestore(&vm_dev->lock, flags); - /* Select and deactivate the queue */ writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL); if (vm_dev->version == 1) { @@ -347,8 +323,6 @@ static void vm_del_vq(struct virtqueue *vq) } vring_del_virtqueue(vq); - - kfree(info); } static void vm_del_vqs(struct virtio_device *vdev) @@ -375,9 +349,7 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in { struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); bool (*notify)(struct virtqueue *vq); - struct virtio_mmio_vq_info *info; struct virtqueue *vq; - unsigned long flags; unsigned int num; int err; @@ -399,13 +371,6 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in goto error_available; } - /* Allocate and fill out our active queue description */ - info = kmalloc(sizeof(*info), GFP_KERNEL); - if (!info) { - err = -ENOMEM; - goto error_kmalloc; - } - num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX); if (num == 0) { err = -ENOENT; @@ -463,13 +428,6 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY); } - vq->priv = info; - info->vq = vq; - - spin_lock_irqsave(&vm_dev->lock, flags); - list_add(&info->node, &vm_dev->virtqueues); - spin_unlock_irqrestore(&vm_dev->lock, flags); - return vq; error_bad_pfn: @@ -481,8 +439,6 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY); WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY)); } - kfree(info); -error_kmalloc: error_available: return ERR_PTR(err); } @@ -627,8 +583,6 @@ static int virtio_mmio_probe(struct platform_device *pdev) vm_dev->vdev.dev.release = virtio_mmio_release_dev; vm_dev->vdev.config = &virtio_mmio_config_ops; vm_dev->pdev = pdev; - INIT_LIST_HEAD(&vm_dev->virtqueues); - spin_lock_init(&vm_dev->lock); vm_dev->base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(vm_dev->base)) { diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 64cb4b04be7a..8b745ce0cf5f 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -196,7 +196,7 @@ int virtio_device_reset_done(struct virtio_device *dev); size_t virtio_max_dma_size(const struct virtio_device *vdev); #define virtio_device_for_each_vq(vdev, vq) \ - list_for_each_entry(vq, &vdev->vqs, list) + list_for_each_entry(vq, &(vdev)->vqs, list) /** * struct virtio_driver - operations for a virtio I/O driver -- 2.31.1.272.g89b43f80a514

7 months

1
0
0 0

Re: Discussion Virtio with pKVM / FFA

by Viresh Kumar

Hello everyone, Moving the discussion from google doc [1] to email (Sorry, it was becoming impossible to follow and reply there). FWIW, I am not the best person to answer all questions here, that would be Armelle as she understand the requirements and the end goal much better than I do. I can though try to answer from kernel's perspective, based on whatever implementation we have right now. AFAIK, the broad idea is to implement two virtio communication paths from pVM, one to the Linux host (via virtio-pci) and another one to Trusty (via virtio-msg-ffa). In order to not take performance hit at runtime (to map io buffers), the idea is to map whatever amount of memory we can at the beginning and then keep allocating from there. Current setup: What we have achieved until now is virtio-msg communication between host and trusty. We have implemented FFA specific dma-hal [2] to perform FFA memory sharing with trusty. With "reserved-mem" and "memory-region" DT entries (not sure if that is the final solution), we are able to allocate memory the FFA device (which represents bus for all the enumerated devices between trusty/host). This memory is shared with trusty at probe time (from virtio-msg-ffa layer) and the DMA hal later allocates memory from there for coherent allocations and bounce buffers. This works just fine right now. Now looking at "dynamic mapping" section in [1] we are not sure if that will work fine for the end use case, pVM to trusty. It looks like the coco implementation will always end up using dma encrypt/decrypt when a pVM is running and share the memory with host, even when all we want to do is share with trusty. Is that understanding correct ? We would also want to establish virtio-pci (existing tech) based communication between pVM and host, which should use mem decrypt path (?). I am not sure if we need contiguous PA here, contiguous IPA should be sufficient, Armelle? We are also looking for further suggestions to improve the design, as my understanding of memory mapping, dma hal etc. is limited, and maybe there are better ways to do this. -- Viresh [1] https://docs.google.com/document/d/1KyxclKngQ0MShX8Q1YPstZQVIDIctkxfj6lQ0V3… [2] https://web.git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git/tree/…

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