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SubjectRe: [PATCH v5 0/8] KVM: x86: Intel LBR related perf cleanups
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On 10/6/22 02:03, Sean Christopherson wrote:
> PeterZ, I dropped your ACK from v4 because the perf patches were completely
> broken.
>
> Fix a bug where KVM incorrectly advertises PMU_CAP_LBR_FMT to userspace if
> perf has disabled LBRs, e.g. because probing one or more LBR MSRs during
> setup hit a #GP.
>
> The non-KVM patch cleans up a KVM-specific perf API to fix a benign bug
> where KVM ignores the error return from the API.
>
> The remaining patches clean up KVM's PERF_CAPABILITIES mess, which makes
> everything far more complex than it needs to be by
>
> v5:
> - Drop perf patches that removed stubs. The stubs are sadly necessary
> when CPU_SUP_INTEL=n && KVM_INTEL={m,y}, which is possible due to
> KVM_INTEL effectively depending on INTEL || CENTAUR || ZHAOXIN.
> [hint provided by kernel test robot].
> - Add a patch to ignore guest CPUID on host userspace MSR writes.
> - Add supported PERF_CAPABILITIES to kvm_caps to simplify code for all
> parties.
>
> v4
> - https://lore.kernel.org/all/20220901173258.925729-1-seanjc@google.com:
> - Make vmx_get_perf_capabilities() non-inline to avoid references to
> x86_perf_get_lbr() when CPU_SUP_INTEL=n. [kernel test robot]
>
> v3:
> - https://lore.kernel.org/all/20220831000051.4015031-1-seanjc@google.com
> - Drop patches for bug #1 (already merged).
> - Drop misguided "clean up the capability check" patch. [Like]
>
> v2:
> - https://lore.kernel.org/all/20220803192658.860033-1-seanjc@google.com
> - Add patches to fix bug #2. [Like]
> - Add a patch to clean up the capability check.
> - Tweak the changelog for the PMU refresh bug fix to call out that
> KVM should disallow changing feature MSRs after KVM_RUN. [Like]
>
> v1: https://lore.kernel.org/all/20220727233424.2968356-1-seanjc@google.com
>
> Sean Christopherson (8):
> perf/x86/core: Zero @lbr instead of returning -1 in x86_perf_get_lbr()
> stub
> KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs
> KVM: VMX: Fold vmx_supported_debugctl() into vcpu_supported_debugctl()
> KVM: VMX: Ignore guest CPUID for host userspace writes to DEBUGCTL
> KVM: x86: Track supported PERF_CAPABILITIES in kvm_caps
> KVM: x86: Init vcpu->arch.perf_capabilities in common x86 code
> KVM: x86: Handle PERF_CAPABILITIES in common x86's
> kvm_get_msr_feature()
> KVM: x86: Directly query supported PERF_CAPABILITIES for WRMSR checks
>
> arch/x86/events/intel/lbr.c | 6 +---
> arch/x86/include/asm/perf_event.h | 6 ++--
> arch/x86/kvm/svm/svm.c | 3 +-
> arch/x86/kvm/vmx/capabilities.h | 37 ----------------------
> arch/x86/kvm/vmx/pmu_intel.c | 1 -
> arch/x86/kvm/vmx/vmx.c | 51 +++++++++++++++++++++++--------
> arch/x86/kvm/x86.c | 14 ++++-----
> arch/x86/kvm/x86.h | 1 +
> 8 files changed, 52 insertions(+), 67 deletions(-)
>
>
> base-commit: e18d6152ff0f41b7f01f9817372022df04e0d354

Queued, with patches 2-4 destined to kvm/master.

Paolo

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