diff options
Diffstat (limited to 'arch/riscv/kvm/vcpu_pmu.c')
| -rw-r--r-- | arch/riscv/kvm/vcpu_pmu.c | 68 |
1 files changed, 64 insertions, 4 deletions
diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c index 2ebccd73680f..a801ed52dc9b 100644 --- a/arch/riscv/kvm/vcpu_pmu.c +++ b/arch/riscv/kvm/vcpu_pmu.c @@ -230,6 +230,47 @@ static int kvm_pmu_validate_counter_mask(struct kvm_pmu *kvpmu, unsigned long ct return 0; } +static void kvm_riscv_pmu_overflow(struct perf_event *perf_event, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + struct kvm_pmc *pmc = perf_event->overflow_handler_context; + struct kvm_vcpu *vcpu = pmc->vcpu; + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu); + struct riscv_pmu *rpmu = to_riscv_pmu(perf_event->pmu); + u64 period; + + /* + * Stop the event counting by directly accessing the perf_event. + * Otherwise, this needs to deferred via a workqueue. + * That will introduce skew in the counter value because the actual + * physical counter would start after returning from this function. + * It will be stopped again once the workqueue is scheduled + */ + rpmu->pmu.stop(perf_event, PERF_EF_UPDATE); + + /* + * The hw counter would start automatically when this function returns. + * Thus, the host may continue to interrupt and inject it to the guest + * even without the guest configuring the next event. Depending on the hardware + * the host may have some sluggishness only if privilege mode filtering is not + * available. In an ideal world, where qemu is not the only capable hardware, + * this can be removed. + * FYI: ARM64 does this way while x86 doesn't do anything as such. + * TODO: Should we keep it for RISC-V ? + */ + period = -(local64_read(&perf_event->count)); + + local64_set(&perf_event->hw.period_left, 0); + perf_event->attr.sample_period = period; + perf_event->hw.sample_period = period; + + set_bit(pmc->idx, kvpmu->pmc_overflown); + kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_PMU_OVF); + + rpmu->pmu.start(perf_event, PERF_EF_RELOAD); +} + static long kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_attr *attr, unsigned long flags, unsigned long eidx, unsigned long evtdata) @@ -249,7 +290,7 @@ static long kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_att */ attr->sample_period = kvm_pmu_get_sample_period(pmc); - event = perf_event_create_kernel_counter(attr, -1, current, NULL, pmc); + event = perf_event_create_kernel_counter(attr, -1, current, kvm_riscv_pmu_overflow, pmc); if (IS_ERR(event)) { pr_err("kvm pmu event creation failed for eidx %lx: %ld\n", eidx, PTR_ERR(event)); return PTR_ERR(event); @@ -443,6 +484,8 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base, pmc_index = i + ctr_base; if (!test_bit(pmc_index, kvpmu->pmc_in_use)) continue; + /* The guest started the counter again. Reset the overflow status */ + clear_bit(pmc_index, kvpmu->pmc_overflown); pmc = &kvpmu->pmc[pmc_index]; if (flags & SBI_PMU_START_FLAG_SET_INIT_VALUE) { pmc->counter_val = ival; @@ -546,7 +589,13 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base, else if (pmc->perf_event) pmc->counter_val += perf_event_read_value(pmc->perf_event, &enabled, &running); - /* TODO: Add counter overflow support when sscofpmf support is added */ + /* + * The counter and overflow indicies in the snapshot region are w.r.to + * cbase. Modify the set bit in the counter mask instead of the pmc_index + * which indicates the absolute counter index. + */ + if (test_bit(pmc_index, kvpmu->pmc_overflown)) + kvpmu->sdata->ctr_overflow_mask |= BIT(i); kvpmu->sdata->ctr_values[i] = pmc->counter_val; shmem_needs_update = true; } @@ -554,6 +603,15 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base, if (flags & SBI_PMU_STOP_FLAG_RESET) { pmc->event_idx = SBI_PMU_EVENT_IDX_INVALID; clear_bit(pmc_index, kvpmu->pmc_in_use); + clear_bit(pmc_index, kvpmu->pmc_overflown); + if (snap_flag_set) { + /* + * Only clear the given counter as the caller is responsible to + * validate both the overflow mask and configured counters. + */ + kvpmu->sdata->ctr_overflow_mask &= ~BIT(i); + shmem_needs_update = true; + } } } @@ -703,6 +761,7 @@ void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu) pmc = &kvpmu->pmc[i]; pmc->idx = i; pmc->event_idx = SBI_PMU_EVENT_IDX_INVALID; + pmc->vcpu = vcpu; if (i < kvpmu->num_hw_ctrs) { pmc->cinfo.type = SBI_PMU_CTR_TYPE_HW; if (i < 3) @@ -735,13 +794,14 @@ void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu) if (!kvpmu) return; - for_each_set_bit(i, kvpmu->pmc_in_use, RISCV_MAX_COUNTERS) { + for_each_set_bit(i, kvpmu->pmc_in_use, RISCV_KVM_MAX_COUNTERS) { pmc = &kvpmu->pmc[i]; pmc->counter_val = 0; kvm_pmu_release_perf_event(pmc); pmc->event_idx = SBI_PMU_EVENT_IDX_INVALID; } - bitmap_zero(kvpmu->pmc_in_use, RISCV_MAX_COUNTERS); + bitmap_zero(kvpmu->pmc_in_use, RISCV_KVM_MAX_COUNTERS); + bitmap_zero(kvpmu->pmc_overflown, RISCV_KVM_MAX_COUNTERS); memset(&kvpmu->fw_event, 0, SBI_PMU_FW_MAX * sizeof(struct kvm_fw_event)); kvm_pmu_clear_snapshot_area(vcpu); } |