Hi Marc,
On 8/21/25 14:37, Marc Zyngier wrote:
> On Thu, 21 Aug 2025 14:13:52 +0100,
> Ben Horgan <ben.horgan@xxxxxxx> wrote:
>>
>>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>>> index 82ffb3b3b3cf7..feb1a7a708e25 100644
>>> --- a/arch/arm64/kvm/sys_regs.c
>>> +++ b/arch/arm64/kvm/sys_regs.c
>>> @@ -2697,6 +2697,18 @@ static bool access_ras(struct kvm_vcpu *vcpu,
>>> struct kvm *kvm = vcpu->kvm;
>>> switch(reg_to_encoding(r)) {
>>> + case SYS_ERXPFGCDN_EL1:
>>> + case SYS_ERXPFGCTL_EL1:
>>> + case SYS_ERXPFGF_EL1:
>>> + case SYS_ERXMISC2_EL1:
>>> + case SYS_ERXMISC3_EL1:
>>> + if (!(kvm_has_feat(kvm, ID_AA64PFR0_EL1, RAS, V1P1) ||
>>> + (kvm_has_feat_enum(kvm, ID_AA64PFR0_EL1, RAS, IMP) &&
>>> + kvm_has_feat(kvm, ID_AA64PFR1_EL1, RAS_frac, RASv1p1)))) {
>>> + kvm_inject_undefined(vcpu);
>>> + return false;
>>> + }
>>> + break;
>>> default:
>>> if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, RAS, IMP)) {
>>> kvm_inject_undefined(vcpu);
>> The default condition needs updating for the case when
>> ID_AA64PFR0_EL1.RAS = b10 otherwise access to the non-v1 specific RAS
>> registers will result in an UNDEF being injected.
>
> I don't think so. The RAS field is described as such:
>
> UnsignedEnum 31:28 RAS
> 0b0000 NI
> 0b0001 IMP
> 0b0010 V1P1
> 0b0011 V2
> EndEnum
>
> Since this is an unsigned enum, this checks for a value < IMP. Only
> RAS not being implemented is this condition satisfied, and an UNDEF
> injected.
>
> Or am I missing something obvious here (I wouldn't be surprised...)?
No, you are indeed correct. I missed the difference between
kvm_has_feat_enum() and kvm_has_feat(). Sorry for the noise.
>
> M.
>
--
Thanks,
Ben
