On Fri, Apr 29, 2022 at 08:28:48PM -0000, tip-bot2 for Sandipan Das wrote:
> 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;
> + }
> +
This is all fine and dandy but this patch in tip conflicts with the very
similar patch of yours:
5a1bde46f98b ("kvm: x86/cpuid: Only provide CPUID leaf 0xA if host has architectural PMU")
which is already upstream.
So which is it? Should we zap this version in tip instead?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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