Messages in this thread | | | Date | Tue, 26 Apr 2022 10:15:50 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 7/7] kvm: x86/cpuid: Fix CPUID leaf 0xA |
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On Thu, Apr 21, 2022 at 11:16:59AM +0530, Sandipan Das wrote: > On some x86 processors, CPUID leaf 0xA provides information > on Architectural Performance Monitoring features. It > advertises a PMU version which Qemu uses to determine the > availability of additional MSRs to manage the PMCs. > > Upon receiving a KVM_GET_SUPPORTED_CPUID ioctl request for > the same, the kernel constructs return values based on the > x86_pmu_capability irrespective of the vendor. > > This leaf and the additional MSRs are not supported on AMD > processors. If PerfMonV2 is detected, the PMU version is > set to 2 and guest startup breaks because of an attempt to > access a non-existent MSR. Return zeros to avoid this. > > Fixes: a6c06ed1a60a ("KVM: Expose the architectural performance monitoring CPUID leaf") > Reported-by: Vasant Hegde <vasant.hegde@amd.com> > Signed-off-by: Sandipan Das <sandipan.das@amd.com> > --- > arch/x86/kvm/cpuid.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 4b62d80bb22f..6bd65cad75ef 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -872,6 +872,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > union cpuid10_eax eax; > union cpuid10_edx edx; > > + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
This is the obligatory question about HYGON; should they be included here?
x86 is getting a number of me-too patches from both sides, where behaviour has diverged for no raisin and then needs to be fixed up again.
> + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > + break; > + } > + > perf_get_x86_pmu_capability(&cap); > > /* > -- > 2.32.0 >
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