Re: [PATCH v7 0/8] target/arm: fully model WFxT instructions for A-profile

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

Peter Maydell <peter.maydell@linaro.org> writes:

> On Fri, 12 Jun 2026 at 18:18, Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>> Peter Maydell <peter.maydell@linaro.org> writes:
>>
>> > On Fri, 29 May 2026 at 09:29, Alex Bennée <alex.bennee@linaro.org> wrote:
>> >>
>> >> 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 refactoring from the previous iterations of the patch have now
>> >> been merged.
>> >>
>> >> I've dropped trying to fully model the global monitor in favour of
>> >> taking advantage of the architectural flexibility to have an IMPDEF
>> >> event wake up for any reason. We treat the setting of exclusive_addr
>> >> as such a reason because it indicates the current vCPU is in a ldstx
>> >> exclusive region and we don't want the guest to deadlock. This does mean
>> >> the system won't sleep on WFE enabled locks but people shouldn't be
>> >> relying on QEMU to model real world sleep patterns anyway given the
>> >> efficiency of emulation compared to real HW.
>> >>
>> >> I've written a test case using kvm-unit-tests:
>> >>
>> >>   Message-ID: <20260527111822.1563679-1-alex.bennee@linaro.org>
>> >>   Date: Wed, 27 May 2026 12:18:21 +0100
>> >>   Subject: [kvm-unit-tests PATCH v2] arm: add wfx test case
>> >>   From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <alex.bennee@linaro.org>
>> >>
>> >> All patches are now reviewed.
>> >
>> >
>> >
>> > Applied to target-arm.next, thanks.
>>
>> Is it too late to drop them? I've a fix for 2/8:
>
> That change is already in upstream git, so you'll need to
> send the fix as a standalone patch, I'm afraid.

No worries, I'll fix it up in the re-base.

>
> -- PMM

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro