Re: [PATCH v3] target/arm: handle unaligned PC during tlb probe

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

Jessica Clarke <jrtc27@jrtc27.com> writes:

> On Thu, Dec 04, 2025 at 08:35:40PM +0000, Alex Bennée wrote:
>> PC alignment faults have priority over instruction aborts and we have
>> code to deal with this in the translation front-ends. However during
>> tb_lookup we can see a potentially faulting probe which doesn't get a
>> MemOp set. If the page isn't available this results in
>> EC_INSNABORT (0x20) instead of EC_PCALIGNMENT (0x22).
>> 
>> As there is no easy way to set the appropriate MemOp in the
>> instruction fetch probe path lets just detect it in
>> arm_cpu_tlb_fill_align() ahead of the main alignment check. We also
>> teach arm_deliver_fault to deliver the right syndrome for
>> MMU_INST_FETCH alignment issues.
>> 
>> Fixes: https://gitlab.com/qemu-project/qemu/-/issues/3233
>> Tested-by: Jessica Clarke <jrtc27@jrtc27.com>
>
> v3 is different enough from the tested RFC that maybe this shouldn't
> have been carried forwards, but I've now tested this v3 and it does
> indeed still fix the issue in my testing.

I did re-test myself and figured it was only adding to the robustness
but thanks for re-confirming its working for you.

>
> Thanks,
> Jessica

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro