Re: [PATCH v3 00/32] target/arm: fully model WFxT instructions for A-profile

["Alex Bennée" <alex.bennee@linaro.org>]

Alex Bennée <alex.bennee@linaro.org> writes:

> This series fully models the behaviour of WFxT instructions. We
> already had support for WFE for M-profile but we left off A-profile as
> it has more potential sources of wake-ups. The main one is the event
> stream which includes events from significant bits of the timer
> ticking over.
>
> The series starts with some refactoring of the syndrome register
> helpers to use registerfields. We then expand the WFIT trap handling
> to report the register used. We then implement the event stream events
> for SEV, global monitor and the timer related ones before enabling WFE
> for A-profile and then finally WFET.
>
> Note on AI usage. As an experiment I previously posted an RFC series
> with the help of Gemini. This series however is a ground up
> re-implementation which takes some different approaches on modelling
> the event stream. In particular rather than running multiple timers we
> use the same wxft timer and just compute if the timeout or timer event
> will come first.
>
> v2
>   - I've kept the tests separate, see:
>
>     Message-ID: <20260417164328.1009132-1-alex.bennee@linaro.org>
>     Date: Fri, 17 Apr 2026 17:43:20 +0100
>     Subject: [PATCH 0/7] tests/tcg: more capabilities for aarch64-softmmu tests
>     From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <alex.bennee@linaro.org>
>
>   - tweaks to global monitor behaviour
>   - STLR/STL will also trigger events to avoid deadlocks
>   - see under the --- in the patches for details
>
> v3
>   - fixed the WFE exception handling
>
> Alex.
>
> Alex Bennée (32):
>   target/arm: migrate basic syndrome helpers to registerfields
>   target/arm: migrate system/cp trap syndromes to registerfields
>   target/arm: migrate FP/SIMD trap syndromes to registerfields
>   target/arm: migrate eret trap syndromes to registerfields
>   target/arm: migrate SME trap syndromes to registerfields
>   target/arm: migrate PAC trap syndromes to registerfields
>   target/arm: migrate BTI trap syndromes to registerfields
>   target/arm: migrate BXJ trap syndromes to registerfields
>   target/arm: migrate Granule Protection traps to registerfields
>   target/arm: migrate fault syndromes to registerfields
>   target/arm: migrate debug syndromes to registerfields
>   target/arm: migrate wfx syndromes to registerfields
>   target/arm: migrate gcs syndromes to registerfields
>   target/arm: migrate memory op syndromes to registerfields
>   target/arm: migrate check_hcr_el2_trap to use syndrome helper
>   target/arm: use syndrome helpers in arm_cpu_do_interrupt_aarch32_hyp
>   target/arm: use syndrome helpers to set SAME_EL EC bit
>   target/arm: make whpx use syndrome helpers for decode
>   target/arm: make hvf use syndrome helpers for decode
>   target/arm: use syndrome helpers in merge_syn_data_abort
>   target/arm: use syndrome helpers to query VNCR bit
>   target/arm: remove old syndrome defines
>   target/arm: report register in WFIT syndromes

Peter,

Do you think you could take the patches up to here so I don't need to
hold the re-factoring patches in the tree?

>   target/arm: teach arm_cpu_has_work about halting reasons
>   target/arm: redefine event stream fields
>   target/arm: ensure aarch64 DISAS_WFE will exit
>   target/arm: implements SEV/SEVL for all modes
>   target/arm: hoist event broadcast code into a helper
>   target/arm: implement global monitor events
>   target/arm: enable event stream on WFE instructions
>   target/arm: handle the WFE trap case
>   target/arm: implement WFET
>
>  target/arm/cpu.h               |  27 ++
>  target/arm/internals.h         |  31 +-
>  target/arm/syndrome.h          | 595 +++++++++++++++++++++++++++------
>  target/arm/tcg/helper-defs.h   |   5 +-
>  target/arm/tcg/translate.h     |  32 ++
>  target/arm/tcg/a32.decode      |   5 +-
>  target/arm/tcg/a64.decode      |   5 +-
>  target/arm/tcg/t16.decode      |   4 +-
>  target/arm/tcg/t32.decode      |   4 +-
>  target/arm/arm-powerctl.c      |   4 +-
>  target/arm/cpu.c               |  53 ++-
>  target/arm/helper.c            |  12 +-
>  target/arm/hvf/hvf.c           |  14 +-
>  target/arm/kvm.c               |   5 +-
>  target/arm/machine.c           |   2 +-
>  target/arm/tcg/debug.c         |   2 +-
>  target/arm/tcg/op_helper.c     | 231 +++++++++++--
>  target/arm/tcg/tlb_helper.c    |   6 +-
>  target/arm/tcg/translate-a64.c |  60 +++-
>  target/arm/tcg/translate.c     |  35 +-
>  target/arm/tcg/vfp_helper.c    |   5 +-
>  target/arm/whpx/whpx-all.c     |  13 +-
>  22 files changed, 946 insertions(+), 204 deletions(-)

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro