iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: x86/pmu: Prevent the PMU from counting disallowed events

Browse Source 
When counting "Instructions Retired" (0xc0) in a guest, KVM will
occasionally increment the PMU counter regardless of if that event is
being filtered. This is because some PMU events are incremented via
kvm_pmu_trigger_event(), which doesn't know about the event filter. Add
the event filter to kvm_pmu_trigger_event(), so events that are
disallowed do not increment their counters.

Fixes: 9cd803d496 ("KVM: x86: Update vPMCs when retiring instructions")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230307141400.1486314-2-aaronlewis@google.com
[sean: prepend "pmc" to the new function]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Aaron Lewis 2023-03-07 14:13:56 +00:00 committed by Sean Christopherson
parent 4fa5843d81
commit dfdeda67ea
1 changed files with 8 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/x86/kvm/pmu.c
View File

@ -400,6 +400,12 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
return is_fixed_event_allowed(filter, pmc->idx); return is_fixed_event_allowed(filter, pmc->idx);
} }
static bool pmc_event_is_allowed(struct kvm_pmc *pmc)
{
return pmc_is_globally_enabled(pmc) && pmc_speculative_in_use(pmc) &&
check_pmu_event_filter(pmc);
}
static void reprogram_counter(struct kvm_pmc *pmc) static void reprogram_counter(struct kvm_pmc *pmc)
{ {
struct kvm_pmu *pmu = pmc_to_pmu(pmc); struct kvm_pmu *pmu = pmc_to_pmu(pmc);
@ -409,10 +415,7 @@ static void reprogram_counter(struct kvm_pmc *pmc)
pmc_pause_counter(pmc); pmc_pause_counter(pmc);
if (!pmc_speculative_in_use(pmc) || !pmc_is_globally_enabled(pmc)) if (!pmc_event_is_allowed(pmc))
goto reprogram_complete;
if (!check_pmu_event_filter(pmc))
goto reprogram_complete; goto reprogram_complete;
if (pmc->counter < pmc->prev_counter) if (pmc->counter < pmc->prev_counter)
@ -688,7 +691,7 @@ void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id)
for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) { for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) {
pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i); pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i);
if (!pmc || !pmc_is_globally_enabled(pmc) || !pmc_speculative_in_use(pmc)) if (!pmc || !pmc_event_is_allowed(pmc))
continue; continue;
/* Ignore checks for edge detect, pin control, invert and CMASK bits */ /* Ignore checks for edge detect, pin control, invert and CMASK bits */