diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-11-10 05:28:53 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-02-01 20:35:48 +0300 |
| commit | d2b321ea9380564510d281d45ccd2b424da14e7f (patch) | |
| tree | 8f2e98b5310b214113728440196d7dc3ed12dc80 /arch/x86 | |
| parent | e5a65d4f723ab9997deab798c539e6bfd71f8440 (diff) | |
| download | linux-d2b321ea9380564510d281d45ccd2b424da14e7f.tar.xz | |
KVM: x86/pmu: Process only enabled PMCs when emulating events in software
Mask off disabled counters based on PERF_GLOBAL_CTRL *before* iterating
over PMCs to emulate (branch) instruction required events in software. In
the common case where the guest isn't utilizing the PMU, pre-checking for
enabled counters turns a relatively expensive search into a few AND uops
and a Jcc.
Sadly, PMUs without PERF_GLOBAL_CTRL, e.g. most existing AMD CPUs, are out
of luck as there is no way to check that a PMC isn't being used without
checking the PMC's event selector.
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Link: https://lore.kernel.org/r/20231110022857.1273836-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/pmu.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 7b5563ff259c..c04c3f37a1b8 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -847,11 +847,20 @@ static inline bool cpl_is_matched(struct kvm_pmc *pmc) void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id) { + DECLARE_BITMAP(bitmap, X86_PMC_IDX_MAX); struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); struct kvm_pmc *pmc; int i; - kvm_for_each_pmc(pmu, pmc, i, pmu->all_valid_pmc_idx) { + BUILD_BUG_ON(sizeof(pmu->global_ctrl) * BITS_PER_BYTE != X86_PMC_IDX_MAX); + + if (!kvm_pmu_has_perf_global_ctrl(pmu)) + bitmap_copy(bitmap, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX); + else if (!bitmap_and(bitmap, pmu->all_valid_pmc_idx, + (unsigned long *)&pmu->global_ctrl, X86_PMC_IDX_MAX)) + return; + + kvm_for_each_pmc(pmu, pmc, i, bitmap) { if (!pmc_event_is_allowed(pmc)) continue; |