[VIRT-241 # QEMU ARMv8.3 support ]
Finished filling out the sub-tasks for v8.3. Added some implementation
notes to some of those tasks as I reread the relevant documentation.
[VIRT-246 # ARMv8.1-LOR Limited Ordering Regions ]
Posted a trivial implementation.
[VIRT-247 # ARMv8.1-HPD and ARMv8.2-AA32HPD ]
Posted.
[Upstream]
Dirty tlb patches and decodetree changes squeeked in for softfreeze.
Another round of tlb flush reduction for aa64. This time exposing
asid's to the softmmu core and allowing it to flush when necessary.
Some more work toward moving x86 softmmu load sequences out of line.
The bulk of the code for 32-bit is now written, but it doesn't work yet.
Fix my thinko wrt divdeu and power7.
[GCC]
The cleanup part of my atomics patch set has been approved and committed.
Posted v3 of the out-of-line atomics part as well.
r~
Upstream Work ([VIRT-109])
==========================
- reviewed {Qemu-arm} {RFC v4 00/71} per-CPU locks Message-Id:
<20181025151103.GA19931@flamenco>
- this is a precursor to Emilio's {RFC 00/48} Plugin support
Message-Id: <20181025172057.20414-1-cota(a)braap.org>
[VIRT-109] https://projects.linaro.org/browse/VIRT-109
QEMU Tooling ([VIRT-252])
=========================
[VIRT-252] https://projects.linaro.org/browse/VIRT-252
QEMU plugin support ([VIRT-280])
- go through Emilio's {RFC 00/48} Plugin support Message-Id:
<20181025172057.20414-1-cota(a)braap.org> :todo
- port my example tools to his framework
[VIRT-280] https://projects.linaro.org/browse/VIRT-280
Kernel Debug via gdbstub
- started re-spin of [KVM/QEMU guest debug fix]
- reviewed/tested problem fixed by {Qemu-devel} {PATCH 0/5}
target/arm: KVM vs ARMISARegisters Message-Id:
<20181024113709.16599-1-richard.henderson(a)linaro.org>
- found a weird bug w.r.t single-stepping first instruction
- started down the debugging rabbit hole
[KVM/QEMU guest debug fix]
https://github.com/stsquad/qemu/tree/kvm/fix-breakpoints-v2
Other Tasks
===========
- Wrote up [KVM Forum 2018 report]
- started looking at {RFC PATCH v2 00/23} KVM: arm64: Initial support
for SVE guests Message-Id:
<1538141967-15375-1-git-send-email-Dave.Martin(a)arm.com>
[KVM Forum 2018 report]
https://collaborate.linaro.org/display/CR/20181024+KVM+Forum+2018
Completed Reviews [2/2]
=======================
{PATCH v2 0/3} Modern shell scripting (use $() instead of ``)
Message-Id: <20181018031723.23459-1-maozhongyi(a)cmss.chinamobile.com>
- CLOSING NOTE [2018-10-31 Wed 15:37]
The bit that touched bootstrap was fine
{Qemu-arm} {RFC v4 00/71} per-CPU locks
Message-Id: <20181025151103.GA19931@flamenco>
- CLOSING NOTE [2018-10-31 Wed 16:58]
Looks good, needs a minor tweak for linux-user mode. Will check
final patches on the next iteration.
Absences
========
- Christmas Holidays
- Connect BKK19 (1-5th April 2019)
Current Review Queue
====================
* {RFC 00/48} Plugin support
Message-Id: <20181025172057.20414-1-cota(a)braap.org>
* {RFC PATCH v2 00/23} KVM: arm64: Initial support for SVE guests
Message-Id: <1538141967-15375-1-git-send-email-Dave.Martin(a)arm.com>
* {PATCH 0/7} Acceptance Tests: basic architecture support
Message-Id: <20181004151429.7232-1-crosa(a)redhat.com>
* {PATCH v7 00/19} Fixing record/replay and adding reverse debugging
Message-Id: <20181010133333.24538.53169.stgit@pasha-VirtualBox>
* {PATCH v2 0/3} Bootstrap Python venv and acceptance/functional tests
Message-Id: <20181009041826.19462-1-crosa(a)redhat.com>
* {Qemu-arm} {PATCH 00/13} target/arm: Implement v8M stack limit checks
Message-Id: <20181002163556.10279-1-peter.maydell(a)linaro.org>
--
Alex Bennée
Progress:
* VIRT-65 [QEMU upstream maintainership]
- code review
- target-arm pull requests
- lots of pull request processing (softfreeze was this week)
- investigated and sent patches to fix a bug where a PC related
pullrequest was failing tests on my merge test setup (turned
out to be a build system issue where we were doing things in
configure that meant make didn't notice it needed to rerun it)
- some simple patches for coverity issues
thanks
-- PMM
[LLVM-203] Code-Size investigation with PGO
- Finished up the remain tasks and resolved the ticket.
- Tidied up the patches and added tests so that I can potentially
share them with other interested parties.
-- Writing tests took a lot longer than I thought as it involves
faking a profile and there were quite a few caveats to doing that.
Some prototyping in LLVM and LLD for some internal ABI discussions.
* 1 day off
== Progress ==
* FDPIC
- Cortex-M fix for binutils committed. uClibc-ng patch on-going
- GCC: handling feedback on v3 patches.
Trying to build/check xtensa uclinux toolchain to check my patches
do not affect it. No satisfactory reference build yet.
* GCC upstream validation:
- reported a few regressions
- one of last week's regressions is causing timeouts on some
validations, thus delaying the full queue. I haven't isolated the
cause yet
- dealing with some random results, again
* GCC:
- bug report on aarch64 about misaligned accesses. Waiting for more
details to reproduce the problem.
* misc (conf-calls, meetings, emails, ....)
- Benchmarking harness hopefully fixed
- reviewing infra script patches
- bugzilla cleanup
== Next ==
FDPIC:
- GCC: followup v3 patches
- uclibc-ng: look at how to test fdpic mode with openadk
- use qemu-system mode to run more tests
Benchmarking:
- fix harness until they support gcc-8
=== Work done during this past week ===
* GNU-296 / GCC PR85434 / CVE-2018-12886: upstream review
+ avoid useless cmp after eors
+ fix another missing earlyclobber
+ full Thumb-1, Thumb-2 and Arm bootstrap with testing with and
without -fPIC, with and without -fstack-protector-all
* Continue patch to further update cpus and architectures in bfd:
external review
+ also teach GAS about Armv5TEJ and newer wrt. bfd architectures tags
+ fix ld action in run_dump_test
+ add testing for all this and submit for external review
* Resurrect code size optimization for fmul/dmul from Tony Wang:
+ rebase on trunk
* Line management
=== Plan for week 43 ===
* LLVM-432 (Support arithmetic on FileCheck regex variable):
+ extend testcase coverage (add tests for latest syntax change and
add more negative testing)
+ finish cleaning up the code
* Try to reproduce perf issue mentioned in week #30's weekly report on
latest perf
* Line management
Progress:
* Attended OSS Europe/KVM Forum
- as usual, a good week (helpful conversations, interesting sessions)
- full conference writeup later in the week
thanks
-- PMM
[VIRT-198 # QEMU: SVE Emulation Support ]
Last of the patches merged to mainline. Epic is now closed.
[VIRT-282 # QEMU: Accelerate TCG with KVM ]
A hallway talk with Paolo lead to a write-up, and Alex encouraged me to create
the epic. The epic description contains a link to the write-up, if anyone is
interested. I'd like to at least create a vm, measure some round-trip costs,
and properly gauge the level of difficulty. Beyond that... we'll see.
[Upstream]
Patch review:
- risc-v decodetree patches v2.
Produced some patches against decodetree itself in response.
I'm hopeful to see a much cleaner v3.
- per-cpu locks
[KVM Forum]
- Unsurprisingly, lots of people worked on speculation mitigation this year.
- Lots of focus on "ram", and the allocation and management thereof.
- Four talks on improving nested virtualization.
- The rest to follow in the trip report.
r~
== Progress ==
* FDPIC
- Posted binutils and uClibc-ng patches to fix cortex-M support, under
discussion
- GCC: handling feedback on v3 patches.
Experimented thumb-1 builds, failed.
* GCC upstream validation:
- reported a few regressions
- dealing with some random results, again
* GCC:
- bug report on aarch64 about misaligned accesses. Waiting for more
details to reproduce the problem.
* misc (conf-calls, meetings, emails, ....)
- Working on fixes of our benchmarking harness to support new gcc-8 releases.
== Next ==
FDPIC:
- GCC: followup v3 patches
- uclibc-ng: look at how to test fdpic mode with openadk
- use qemu-system mode to run more tests
Benchmarking:
- fix harness until they support gcc-8
== This Week ==
* GNU-405: Implement division using vrecpe / vrecps (4/10)
- Patch validated and posted upstream.
* SVE ACLE intrinsics (4/10)
- Going thru documentation.
* GNU-235: Provide value-range info for erf family of functions (1/10)
- Working on patch.
* Misc (1/10)
- Meetings
== Next Week ==
- Continue GNU-235, SVE ACLE intrinsics
Upstream Work ([VIRT-109])
==========================
- started looking at {Qemu-arm} {RFC v4 00/71} per-CPU locks
Message-Id: <20181025151103.GA19931@flamenco>
- this is a precursor to Emilio's {RFC 00/48} Plugin support
Message-Id: <20181025172057.20414-1-cota(a)braap.org>
[VIRT-109] https://projects.linaro.org/browse/VIRT-109
Other Tasks
===========
- Attended KVM Forum 2018
- I am now Spectre'd out ;-)
- Some interesting discussions on upstream CI
- will save the rest of my notes for the conference report
- Delivered QEMU Keynote/Status report @ KVM Forum 2018
- Here are [the slides]
[the slides]
http://people.linaro.org/~alex.bennee/org/presentations/kvm18-qemu-keynote.…
Current Review Queue
====================
* {Qemu-arm} {RFC v4 00/71} per-CPU locks
Message-Id: <20181025151103.GA19931@flamenco>
* {RFC 00/48} Plugin support
Message-Id: <20181025172057.20414-1-cota(a)braap.org>
* {PATCH v2 0/3} Modern shell scripting (use $() instead of ``)
Message-Id: <20181018031723.23459-1-maozhongyi(a)cmss.chinamobile.com>
* {PATCH 0/7} Acceptance Tests: basic architecture support
Message-Id: <20181004151429.7232-1-crosa(a)redhat.com>
* {PATCH v7 00/19} Fixing record/replay and adding reverse debugging
Message-Id: <20181010133333.24538.53169.stgit@pasha-VirtualBox>
* {PATCH v2 0/3} Bootstrap Python venv and acceptance/functional tests
Message-Id: <20181009041826.19462-1-crosa(a)redhat.com>
--
Alex Bennée
[LLVM-203] Investigation into profiling and code-size optimizations
- Collected the remaining data I needed over the weekend.
- Wrote up report
- Rebased patches on tip of trunk
- Attached results and report to Jira issue.
- A one line summary of the results is that if you are lucky you can
get close to peak performance at close to Os code size if your program
happens to spend most of its time in a few small places. If you are
unlucky then increased inlining and unrolling can still result in an
overall code size increase over -O3 but the effect will be limited.
[LLVM-158] Monitor and maintain buildbots
- Relatively quiet week, a couple of patches pinged for fixes/reverts.
== This Week ==
* TCWG-1234: Coremark regression (7/10)
- Fixed golang regressions with the patch.
- Posted patch upstream to change hoisting order and apply cost model.
* Public holiday (2/10)
* Misc (1/10)
- Meetings
== Next Week ==
- TCWG-319, SVE
[VIRT-214 # SVE System Registers ]
v4 posted and merged to target-arm.next; will be in master shortly.
That will complete basic SVE system mode support.
[UPSTREAM]
tcg-next patches collected and flushed.
Dug into apparently excessive overhead in aarch64 guest tlb flushing, noticed
by chance while doing something else. Two patches upstream, several more
written but need cleanup. Total overhead down from 25% to 9%.
r~
=== Work done during this past week ===
* GNU-296 / GCC PR85434 / CVE-2018-12886:
+ few more issues fixed and associated testing
+ now also running Thumb-1 bootstrap and testing
* Prepare patch to further update cpus and architectures in bfd
* Line management
=== Plan for week 43 ===
* GNU-296 / GCC PR85434 / CVE-2018-12886:
+ finish testing, and submit new stack protector patch for upstream review
* LLVM-432 (Support arithmetic on FileCheck regex variable):
+ extend testcase coverage (add tests for latest syntax change and
add more negative testing)
+ finish cleaning up the code
* Try to reproduce perf issue mentioned in week #30's weekly report on
latest perf
* Line management
Progress:
* VIRT-65 [QEMU upstream maintainership]
- code review
- use ID registers as master source for "should this CPU
have this feature" information (rth)
- clean up 32-bit Neon to use vector infrastructure (rth)
- don't let the kernel get loaded on top of our builtin
bootloader if it happens to ask for a zero text offset
- Xilinx Versal board patches
- target-arm pull requests
- some minor patches to fix new clang warnings
- preparation for KVM Forum/QEMU Summit etc next week
thanks
-- PMM
== Progress ==
* FDPIC
- GCC: handled feedback on v3 patches.
Not much info on how to test other existing uclinux targets.
Noticed that GCC trunk build fails when targeting cortex-m23
(v8-m.baseline), problems in support libs (libgcc, newlib)
* GCC upstream validation:
- reported a few regressions
- dealing with some random results, again
* GCC:
- bug report on aarch64 about misaligned accesses. Waiting for more
details to reproduce the problem.
* misc (conf-calls, meetings, emails, ....)
== Next ==
FDPIC:
- GCC: discuss v3 patches where the way forward is not clear yet
- uclibc-ng: look at how to test fdpic mode with openadk
- use qemu-system mode to run more tests
[LLVM-203] (was TCWG-1424, we've moved issues to a new project)
Started writing up results to close out this investigation.
- Reran some sample profiling test cases with a higher sample rate.
- Investigated why some test cases exploded in code-size with LTO.
- Got some results for thin LTO (broadly similar to LTO).
- Discovered that I need to pass in extra linker options to enable LTO
to use the new pass manager, sample profiling and setting of
optimisation level.
-- Need to rerun these configurations over the weekend.
- Have most of the surrounding text of the report written, now need to
work on presentation of results.
[TCWG-1473] Fix big-endian linux kernel builds for AArch32
Now committed upstream
Holiday Friday
o LLVM
* Machine Outliner on ARM prototype:
- Still debugging Thumb1 issues in Spec2K6
- Investigating issues in PIC mode
* Bots babysitting
o Misc
* Various meetings and discussions.
[VIRT-214 # SVE System Registers ]
Posted v3 patch set.
[VIRT-281 # Extend gdbstub for SVE ]
Crashed gdb. Posted patch fixing buffer overrun.
It was suggested to me that qemu's gdbstub might not support enough
modern bits of the remote protocol for SVE. So I spent quite a bit
of time reading up on the protocol and beginning to review
[PATCH v2 00/15] gdbstub: support for the multiprocess extension
In the end I'm not convinced there's anything missing for SVE.
I think I'm going to have to examine upstream gdb more closely,
running gdbserver proper.
[Upstream]
Collecting patches for tcg-next.
Misc patch review.
[GCC]
Pinged my LSE patch set from 2 Oct.
r~
== Progress ==
* FDPIC
- GCC: send v3 patches, got some feedback: will need another iteration
* GCC upstream validation:
- reported a few regressions
- dealing with some random results, again
* GCC:
- looking at bug report on aarch64 about misaligned accesses. Need
more details to reproduce the problem
* Newlib
- got a few small patches accepted
* misc (conf-calls, meetings, emails, ....)
== Next ==
FDPIC:
- GCC: handle v3 patches feedback
- uclibc-ng: look at how to test fdpic mode with openadk
=== Work done during this past week ===
* TCWG-1428 (Support arithmetic on FileCheck regex variable):
+ continued cleaning up code and painfully rebased it on recent trunk
* GNU-296 / GCC PR85434 / CVE-2018-12886:
+ fixed changes to routines for PIC access to use specified register
+ fixed 2 more issues in stack protector new instruction patterns
+ testing for arm and thumb2, now starting over due to one of the above issues
* GNU-580 / PR86968: in progress
+ investigate, try 2 approaches, need to start looking into 3rd approach
* Line management.
=== Plan for week 42 ===
* GNU-296 / GCC PR85434 / CVE-2018-12886:
+ finish testing, and submit new stack protector patch for upstream review
* TCWG-1428 (Support arithmetic on FileCheck regex variable):
+ extend testcase coverage (add tests for latest syntax change and
add more negative testing)
+ finish cleaning up the code
* GNU-580 / PR86968: in progress
+ attempt 3rd approach
* Try to reproduce perf issue mentioned in week #30's weekly report on
latest perf
* Line management:
+ continue progress on rotations
+ start preparing first AFDS
[TCWG-1473] Fix -fno-integrated-as and -mbig-endian (Linux Kernel
Build with clang)
- Needed some revision to handle linker emulation. Patch in upstream review
[TCWG-1474] Fix out of range branch (CBZ) when -fimplicit-it (or
-fno-integrated-as) and certain kinds of inline assembly
- Committed upstream.
[TCWG-1424] Code-size investigations with PGO
- Marking functions for size optimisation at the earliest possible
stage improves code-size for little loss in performance. The main
beneficiary is that loops are not unrolled in size optimised functions
and inline thresholds are lower.
- LTO with instrumented profiling still sees large increase in size.
Originally thought my changes weren't working with LTO but I think
that something else is happening.
-- Found out that the profiling information isn't being sent to the
LTO code-generator (although it should be present as IR annotations
from the objects.
-- There is an option to pass the sample profile through to the LTO
code-generator but not an instrumented profile file.
-- It seems like the LTO plugin doesn't use the new pass manager
unless a separate option is passed through to the code-generator.
-- It seems like Thin-LTO is where most of upstream development is
these days and there is a slightly different pass pipeline, and some
interaction with profiling. Worth some more experiments.
First draft made of incorporating YVR18 Jira discussion into
Confluence https://collaborate.linaro.org/display/TCWG/JIRA+Usage+and+Best+Practices
Progress:
* VIRT-65 [QEMU upstream maintainership]
- code review:
+ Xilinx Versal SoC support
- investigated problem with a "suppress this warning patch" which
gcc 8 didn't like. It turns out that _Pragma() in GCC is a bit
of a disaster area; fortunately we only need to suppress a
warning here for clang, so we can just avoid using _Pragma() with GCC.
(cf GCC bugs 85153, 69558, 82335, 66099, 55578, 69543.
clang is not flawless here either: cf clang bugs 31999, 15129, 35154.
The clang false-positive warning we're working around is bug 39113.)
* VIRT-164 [improve Cortex-M emulation]
- stack-limit emulation patches have now gone into master, so this
epic can be closed out. Some v8M work will continue under
VIRT-268 (notably FP emulation); bugfixing and similar
small work will go under the general VIRT-65 maintainership epic.
* VIRT-215 ["run microvisors", aka support AArch32 Hyp mode]
- working through some of the HCR bits we don't implement, to see
if any of them are the cause of the failures I see with AArch32
hypervisors. (Sadly they don't seem to be.) Sent out patches
implementing HCR.{FB,DC,VI,VF,PTW} and fixing some syndrome
reporting corner cases where AArch32 differs from AArch64.
thanks
-- PMM
