Re: [PATCH] target/arm: Don't skip access flag fault for AccessType_AT

[Zenghui Yu <zenghui.yu@linux.dev>]

Hi Peter,

On 3/20/26 1:17 AM, Peter Maydell wrote:
> On Tue, 17 Mar 2026 at 12:25, Zenghui Yu <zenghui.yu@linux.dev> wrote:
> >
> > As per the pseudo code from DDI0487 M.a.a (on J1-16021) AArch64.S1Walk():
> >
> >   // Check descriptor AF bit
> >   elsif (descriptor<10> == '0' && walkparams.ha == '0' &&
> >           (!accdesc.acctype IN {AccessType_DC, AccessType_IC} ||
> >            boolean IMPLEMENTATION_DEFINED "Generate access flag fault on IC/DC operations")) then
> >       fault.statuscode = Fault_AccessFlag;
> >
> > an access flag fault should be generated for AccessType_AT, if the AF bit
> > is 0 and !param.ha.
> 
> Did you find this by code inspection, or because it caused
> a guest to go wrong?

This was noticed when I was fixing the AT selftest on KVM side [*].

[*] https://lore.kernel.org/r/d58819b9-c745-4551-8ea4-e15af3fe63be@linux.dev

Thanks,
Zenghui