diff options
| author | Like Xu <likexu@tencent.com> | 2022-09-23 03:13:54 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-11-09 20:31:36 +0300 |
| commit | 68fb4757e8678894530ee0b15c29a3567207b970 (patch) | |
| tree | 711ba4357bd7d0f1fa7266f7ca36ca1820a3205e /arch/x86/kvm/pmu.c | |
| parent | dcbb816a2842e41d3ec22605c6760837d800b20a (diff) | |
| download | linux-68fb4757e8678894530ee0b15c29a3567207b970.tar.xz | |
KVM: x86/pmu: Defer reprogram_counter() to kvm_pmu_handle_event()
Batch reprogramming PMU counters by setting KVM_REQ_PMU and thus
deferring reprogramming kvm_pmu_handle_event() to avoid reprogramming
a counter multiple times during a single VM-Exit.
Deferring programming will also allow KVM to fix a bug where immediately
reprogramming a counter can result in sleeping (taking a mutex) while
interrupts are disabled in the VM-Exit fastpath.
Introduce kvm_pmu_request_counter_reprogam() to make it obvious that
KVM is _requesting_ a reprogram and not actually doing the reprogram.
Opportunistically refine related comments to avoid misunderstandings.
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20220831085328.45489-5-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/pmu.c')
| -rw-r--r-- | arch/x86/kvm/pmu.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index be8ce5aeb454..3054b35b4143 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -101,7 +101,11 @@ static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi) struct kvm_pmu *pmu = pmc_to_pmu(pmc); bool skip_pmi = false; - /* Ignore counters that have been reprogrammed already. */ + /* + * Ignore overflow events for counters that are scheduled to be + * reprogrammed, e.g. if a PMI for the previous event races with KVM's + * handling of a related guest WRMSR. + */ if (test_and_set_bit(pmc->idx, pmu->reprogram_pmi)) return; @@ -292,7 +296,7 @@ out: return allow_event; } -void reprogram_counter(struct kvm_pmc *pmc) +static void reprogram_counter(struct kvm_pmc *pmc) { struct kvm_pmu *pmu = pmc_to_pmu(pmc); u64 eventsel = pmc->eventsel; @@ -345,7 +349,6 @@ void reprogram_counter(struct kvm_pmc *pmc) reprogram_complete: clear_bit(pmc->idx, (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi); } -EXPORT_SYMBOL_GPL(reprogram_counter); void kvm_pmu_handle_event(struct kvm_vcpu *vcpu) { @@ -355,10 +358,11 @@ void kvm_pmu_handle_event(struct kvm_vcpu *vcpu) for_each_set_bit(bit, pmu->reprogram_pmi, X86_PMC_IDX_MAX) { struct kvm_pmc *pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, bit); - if (unlikely(!pmc || !pmc->perf_event)) { + if (unlikely(!pmc)) { clear_bit(bit, pmu->reprogram_pmi); continue; } + reprogram_counter(pmc); } @@ -552,12 +556,15 @@ static inline bool eventsel_match_perf_hw_id(struct kvm_pmc *pmc, static inline bool cpl_is_matched(struct kvm_pmc *pmc) { bool select_os, select_user; - u64 config = pmc->current_config; + u64 config; if (pmc_is_gp(pmc)) { + config = pmc->eventsel; select_os = config & ARCH_PERFMON_EVENTSEL_OS; select_user = config & ARCH_PERFMON_EVENTSEL_USR; } else { + config = fixed_ctrl_field(pmc_to_pmu(pmc)->fixed_ctr_ctrl, + pmc->idx - INTEL_PMC_IDX_FIXED); select_os = config & 0x1; select_user = config & 0x2; } |