From: Sean Christopherson <seanjc@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, Like Xu <like.xu.linux@gmail.com>
Subject: [PATCH v2 0/7] KVM: x86: Intel PERF_CAPABILITIES fixes and cleanups
Date: Wed, 3 Aug 2022 19:26:51 +0000 [thread overview]
Message-ID: <20220803192658.860033-1-seanjc@google.com> (raw)
Bug fixes and cleanups related to KVM's handling of PERF_CAPABILITIES.
Bug #1 - Refresh KVM's vPMU after userspace writes PERF_CAPABILITIES, and
then leverage that fix to avoiding checking guest_cpuid_has(X86_FEATURE_PDCM)
during VM-Enter, which is slow enough that it shows up in perf traces[*].
Bug #2 - Don't advertise 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 patches remove unnecessary stubs and unreachable error paths,
which allows for a cleaner fix for bug #2.
[*] https://gist.github.com/avagin/f50a6d569440c9ae382281448c187f4e
v2:
- 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 (7):
KVM: x86: Refresh PMU after writes to MSR_IA32_PERF_CAPABILITIES
perf/x86/core: Remove unnecessary stubs provided for KVM-only helpers
perf/x86/core: Drop the unnecessary return value from
x86_perf_get_lbr()
KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs
KVM: VMX: Use proper type-safe functions for vCPU => LBRs helpers
KVM: VMX: Adjust number of LBR records for PERF_CAPABILITIES at
refresh
KVM: VMX: Simplify capability check when handling PERF_CAPABILITIES
write
arch/x86/events/intel/lbr.c | 6 +---
arch/x86/include/asm/perf_event.h | 55 ++++++++-----------------------
arch/x86/kvm/vmx/capabilities.h | 5 ++-
arch/x86/kvm/vmx/pmu_intel.c | 12 ++-----
arch/x86/kvm/vmx/vmx.c | 6 ++--
arch/x86/kvm/vmx/vmx.h | 53 +++++++++++++++++------------
arch/x86/kvm/x86.c | 4 +--
7 files changed, 58 insertions(+), 83 deletions(-)
base-commit: 93472b79715378a2386598d6632c654a2223267b
--
2.37.1.559.g78731f0fdb-goog
next reply other threads:[~2022-08-03 19:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-03 19:26 Sean Christopherson [this message]
2022-08-03 19:26 ` [PATCH v2 1/7] KVM: x86: Refresh PMU after writes to MSR_IA32_PERF_CAPABILITIES Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 2/7] perf/x86/core: Remove unnecessary stubs provided for KVM-only helpers Sean Christopherson
2022-08-04 8:49 ` Like Xu
2022-08-04 15:07 ` Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 3/7] perf/x86/core: Drop the unnecessary return value from x86_perf_get_lbr() Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 4/7] KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 5/7] KVM: VMX: Use proper type-safe functions for vCPU => LBRs helpers Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 6/7] KVM: VMX: Adjust number of LBR records for PERF_CAPABILITIES at refresh Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 7/7] KVM: VMX: Simplify capability check when handling PERF_CAPABILITIES write Sean Christopherson
2022-08-04 7:52 ` Like Xu
2022-08-04 15:00 ` Sean Christopherson
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