| From fd3a90ddebfcd099d3c4f8dab38fcfce0d54409b Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 27 Apr 2022 17:01:49 +0530 |
| Subject: kvm: x86/cpuid: Only provide CPUID leaf 0xA if host has architectural |
| PMU |
| |
| From: Sandipan Das <sandipan.das@amd.com> |
| |
| [ Upstream commit 5a1bde46f98b893cda6122b00e94c0c40a6ead3c ] |
| |
| 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 |
| 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> |
| Message-Id: <3fef83d9c2b2f7516e8ff50d60851f29a4bcb716.1651058600.git.sandipan.das@amd.com> |
| Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| 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 41b0dc37720e..6e1ea5e85e59 100644 |
| --- a/arch/x86/kvm/cpuid.c |
| +++ b/arch/x86/kvm/cpuid.c |
| @@ -668,6 +668,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) |
| union cpuid10_eax eax; |
| union cpuid10_edx edx; |
| |
| + if (!static_cpu_has(X86_FEATURE_ARCH_PERFMON)) { |
| + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; |
| + break; |
| + } |
| + |
| perf_get_x86_pmu_capability(&cap); |
| |
| /* |
| -- |
| 2.35.1 |
| |