The following commit has been merged into the perf/core branch of tip:
Commit-ID: fafd15ab6dc1fdfff66908e6d9231b124e1875cf
Gitweb: https://git.kernel.org/tip/fafd15ab6dc1fdfff66908e6d9231b124e1875cf
Author: Sandipan Das <sandipan.das@xxxxxxx>
AuthorDate: Thu, 21 Apr 2022 11:16:59 +05:30
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 29 Apr 2022 11:06:27 +02:00
kvm: x86/cpuid: Fix CPUID leaf 0xA
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@xxxxxxx>
Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/54bc7fe4cadf6bdef823bab1fba43d4891d2e1a9.1650515382.git.sandipan.das@xxxxxxx
---
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 b24ca7f..ae1d963 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -887,6 +887,12 @@ 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);
/*
|