Hi Reiji,
On 11/17/21 7:43 AM, Reiji Watanabe wrote:
> When ID_AA64DFR0_EL1.PMUVER or ID_DFR0_EL1.PERFMON is 0xf, which
> means IMPLEMENTATION DEFINED PMU supported, KVM unconditionally
> expose the value for the guest as it is. Since KVM doesn't support
> IMPLEMENTATION DEFINED PMU for the guest, in that case KVM should
> exopse 0x0 (PMU is not implemented) instead.
s/exopse/expose
>
> Change cpuid_feature_cap_perfmon_field() to update the field value
> to 0x0 when it is 0xf.
is it wrong to expose the guest with a Perfmon value of 0xF? Then the
guest should not use it as a PMUv3?
Eric
>
> Fixes: 8e35aa642ee4 ("arm64: cpufeature: Extract capped perfmon fields")
> Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/cpufeature.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index ef6be92b1921..fd7ad8193827 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -553,7 +553,7 @@ cpuid_feature_cap_perfmon_field(u64 features, int field, u64 cap)
>
> /* Treat IMPLEMENTATION DEFINED functionality as unimplemented */
> if (val == ID_AA64DFR0_PMUVER_IMP_DEF)
> - val = 0;
> + return (features & ~mask);
>
> if (val > cap) {
> features &= ~mask;
>
