Re: [PATCH 2/6] KVM: arm64: Fix AArch32 PMUv3 capping

Auger Eric
2021-01-15T13:07:09Z

Hi Marc,

On 1/14/21 11:56 AM, Marc Zyngier wrote:
> We shouldn't expose *any* PMU capability when no PMU has been
> configured for this VM.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/kvm/sys_regs.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 0c0832472c4a..ce08d28ab15c 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1048,8 +1048,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
> } else if (id == SYS_ID_DFR0_EL1) {
> /* Limit guests to PMUv3 for ARMv8.1 */
> val = cpuid_feature_cap_perfmon_field(val,
> - ID_DFR0_PERFMON_SHIFT,
> - ID_DFR0_PERFMON_8_1);
> + ID_DFR0_PERFMON_SHIFT,
> + kvm_vcpu_has_pmu(vcpu) ? ID_DFR0_PERFMON_8_1 : 0);
nit: Maybe you could use the same layout for SYS_ID_AA64DFR0_EL1
andremove cap there.

Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric

> }
>
> return val;
>