On 2023/3/7 22:13, Aaron Lewis wrote:
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.
It would be nice to have:
Reported-by: Jinrong Liang <cloudliang@xxxxxxxxxxx>
, since he also found the same issue.
Fixes: 9cd803d496e7 ("KVM: x86: Update vPMCs when retiring instructions")
Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx>
Reviewed-by: Like Xu <likexu@xxxxxxxxxxx>
---
arch/x86/kvm/pmu.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 612e6c70ce2e..9914a9027c60 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -400,6 +400,12 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
return is_fixed_event_allowed(filter, pmc->idx);
}
+static bool event_is_allowed(struct kvm_pmc *pmc)
Nit, an inline event_is_allowed() here might be better.
+{
+ return pmc_is_enabled(pmc) && pmc_speculative_in_use(pmc) &&
+ check_pmu_event_filter(pmc);
+}
+
static void reprogram_counter(struct kvm_pmc *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);
- if (!pmc_speculative_in_use(pmc) || !pmc_is_enabled(pmc))
- goto reprogram_complete;
-
- if (!check_pmu_event_filter(pmc))
+ if (!event_is_allowed(pmc))
goto reprogram_complete;
if (pmc->counter < pmc->prev_counter)
@@ -684,7 +687,7 @@ 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) {
pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i);
- if (!pmc || !pmc_is_enabled(pmc) || !pmc_speculative_in_use(pmc))
+ if (!pmc || !event_is_allowed(pmc))
continue;
/* Ignore checks for edge detect, pin control, invert and CMASK bits */
