Re: [PATCH v2] KVM: SVM: emulate MSR_IA32_PERF_CAPABILITIES

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 18/06/20 13:13, Vitaly Kuznetsov wrote:
>> state_test/smm_test selftests are failing on AMD with:
>> "Unexpected result from KVM_GET_MSRS, r: 51 (failed MSR was 0x345)"
>> 
>> MSR_IA32_PERF_CAPABILITIES is an emulated MSR on Intel but it is not
>> known to AMD code, emulate it there too (by returning 0 and allowing
>> userspace to write 0). This way the code is better prepared to the
>> eventual appearance of the feature in AMD hardware.
>> 
>> Fixes: 27461da31089 ("KVM: x86/pmu: Support full width counting")
>> Suggested-by: Jim Mattson <jmattson@google.com>
>> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>>  arch/x86/kvm/svm/pmu.c | 29 ++++++++++++++++++++++++++++-
>>  1 file changed, 28 insertions(+), 1 deletion(-)
>
> This is okay and I'll apply it, but it would be even better to move the
> whole handling of the MSR to common x86 code.

I thought about that but intel_pmu_set_msr() looks at
vmx_get_perf_capabilities(), we'll need to abstract this somehow.

-- 
Vitaly