Messages in this thread Patch in this message | | | Date | Wed, 27 Apr 2022 17:32:10 +0800 | Subject | Re: [PATCH v3 7/7] kvm: x86/cpuid: Fix CPUID leaf 0xA | From | Like Xu <> |
| |
On 26/4/2022 9:05 pm, 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 > and Hygon processors. If AMD PerfMonV2 is detected, the PMU
So, why not:
if (!static_cpu_has(X86_FEATURE_ARCH_PERFMON)) break; ?
> 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 | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 4b62d80bb22f..d27d6a8f601a 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -872,6 +872,12 @@ 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 || > + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { > + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > + break; > + } > + > perf_get_x86_pmu_capability(&cap); > > /*
| |