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KVM: x86/pmu: Track mediated PMU counters with mode-specific enables

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Instead of always checking of a counter needs to be disabled for
mode-specific reasons (e.g. Host-Only/Guest-Only bits in SVM), add a
bitmap to track such counters. Set the bit for counters using either
Host-Only or Guest-Only bits in EVENTSEL on SVM.

This bitmap will also be reused in following changes to selectively
apply changes to such counters.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260527234711.4175166-12-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Yosry Ahmed 2026-05-27 23:47:05 +00:00 committed by Sean Christopherson
parent 2ed72677a5
commit c0d4c9c54c
4 changed files with 16 additions and 2 deletions
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2
arch/x86/include/asm/kvm_host.h
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@ -612,6 +612,8 @@ struct kvm_pmu {
DECLARE_BITMAP(pmc_counting_instructions, X86_PMC_IDX_MAX);
DECLARE_BITMAP(pmc_counting_branches, X86_PMC_IDX_MAX);
DECLARE_BITMAP(pmc_has_mode_specific_enables, X86_PMC_IDX_MAX);
u64 ds_area;
u64 pebs_enable;
u64 pebs_enable_rsvd;

1
arch/x86/kvm/pmu.c
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@ -936,6 +936,7 @@ static void kvm_pmu_reset(struct kvm_vcpu *vcpu)
pmu->need_cleanup = false;
bitmap_zero(pmu->reprogram_pmi, X86_PMC_IDX_MAX);
bitmap_zero(pmu->pmc_has_mode_specific_enables, X86_PMC_IDX_MAX);
kvm_for_each_pmc(pmu, pmc, i, pmu->all_valid_pmc_idx) {
pmc_stop_counter(pmc);

9
arch/x86/kvm/pmu.h
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@ -202,8 +202,13 @@ static inline bool pmc_is_locally_enabled(struct kvm_pmc *pmc)
pmc->idx - KVM_FIXED_PMC_BASE_IDX) &
(INTEL_FIXED_0_KERNEL | INTEL_FIXED_0_USER);
return (pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE) &&
!kvm_pmu_call(pmc_is_disabled_in_current_mode)(pmc);
if (!(pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE))
return false;
if (!test_bit(pmc->idx, pmu->pmc_has_mode_specific_enables))
return true;
return !kvm_pmu_call(pmc_is_disabled_in_current_mode)(pmc);
}
extern struct x86_pmu_capability kvm_pmu_cap;

6
arch/x86/kvm/svm/pmu.c
View File

@ -168,6 +168,12 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
pmc->eventsel = data;
pmc->eventsel_hw = (data & ~AMD64_EVENTSEL_HOSTONLY) |
AMD64_EVENTSEL_GUESTONLY;
if (data & AMD64_EVENTSEL_HOST_GUEST_MASK)
__set_bit(pmc->idx, pmu->pmc_has_mode_specific_enables);
else
__clear_bit(pmc->idx, pmu->pmc_has_mode_specific_enables);
kvm_pmu_request_counter_reprogram(pmc);
}
return 0;