| Message ID | 20231229214950.4061381-10-atishp@rivosinc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | RISC-V SBI v2.0 PMU improvements and Perf sampling in KVM guest | expand |
On Sat, Dec 30, 2023 at 3:20 AM Atish Patra <atishp@rivosinc.com> wrote: > > KVM enables perf for guest via counter virtualization. However, the > sampling can not be supported as there is no mechanism to enabled > trap/emulate scountovf in ISA yet. Rely on the SBI PMU snapshot > to provide the counter overflow data via the shared memory. > > In case of sampling event, the host first guest the LCOFI interrupt > and injects to the guest via irq filtering mechanism defined in AIA > specification. Thus, ssaia must be enabled in the host in order to > use perf sampling in the guest. No other AIA dpeendancy w.r.t kernel > is required. > > Signed-off-by: Atish Patra <atishp@rivosinc.com> LGTM. Reviewed-by: Anup Patel <anup@brainfault.org> Regards, Anup > --- > arch/riscv/include/asm/csr.h | 3 +- > arch/riscv/include/asm/kvm_vcpu_pmu.h | 1 + > arch/riscv/include/uapi/asm/kvm.h | 1 + > arch/riscv/kvm/main.c | 1 + > arch/riscv/kvm/vcpu.c | 8 +-- > arch/riscv/kvm/vcpu_onereg.c | 2 + > arch/riscv/kvm/vcpu_pmu.c | 70 +++++++++++++++++++++++++-- > 7 files changed, 77 insertions(+), 9 deletions(-) > > diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h > index 88cdc8a3e654..bec09b33e2f0 100644 > --- a/arch/riscv/include/asm/csr.h > +++ b/arch/riscv/include/asm/csr.h > @@ -168,7 +168,8 @@ > #define VSIP_TO_HVIP_SHIFT (IRQ_VS_SOFT - IRQ_S_SOFT) > #define VSIP_VALID_MASK ((_AC(1, UL) << IRQ_S_SOFT) | \ > (_AC(1, UL) << IRQ_S_TIMER) | \ > - (_AC(1, UL) << IRQ_S_EXT)) > + (_AC(1, UL) << IRQ_S_EXT) | \ > + (_AC(1, UL) << IRQ_PMU_OVF)) > > /* AIA CSR bits */ > #define TOPI_IID_SHIFT 16 > diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h > index d56b901a61fc..af6d0ff5ce41 100644 > --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h > +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h > @@ -36,6 +36,7 @@ struct kvm_pmc { > bool started; > /* Monitoring event ID */ > unsigned long event_idx; > + struct kvm_vcpu *vcpu; > }; > > /* PMU data structure per vcpu */ > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h > index d6b7a5b95874..d5aea43bc797 100644 > --- a/arch/riscv/include/uapi/asm/kvm.h > +++ b/arch/riscv/include/uapi/asm/kvm.h > @@ -139,6 +139,7 @@ enum KVM_RISCV_ISA_EXT_ID { > KVM_RISCV_ISA_EXT_ZIHPM, > KVM_RISCV_ISA_EXT_SMSTATEEN, > KVM_RISCV_ISA_EXT_ZICOND, > + KVM_RISCV_ISA_EXT_SSCOFPMF, > KVM_RISCV_ISA_EXT_MAX, > }; > > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c > index 225a435d9c9a..5a3a4cee0e3d 100644 > --- a/arch/riscv/kvm/main.c > +++ b/arch/riscv/kvm/main.c > @@ -43,6 +43,7 @@ int kvm_arch_hardware_enable(void) > csr_write(CSR_HCOUNTEREN, 0x02); > > csr_write(CSR_HVIP, 0); > + csr_write(CSR_HVIEN, 1UL << IRQ_PMU_OVF); > > kvm_riscv_aia_enable(); > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index b5ca9f2e98ac..f83f0226439f 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -382,7 +382,8 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > if (irq < IRQ_LOCAL_MAX && > irq != IRQ_VS_SOFT && > irq != IRQ_VS_TIMER && > - irq != IRQ_VS_EXT) > + irq != IRQ_VS_EXT && > + irq != IRQ_PMU_OVF) > return -EINVAL; > > set_bit(irq, vcpu->arch.irqs_pending); > @@ -397,14 +398,15 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > { > /* > - * We only allow VS-mode software, timer, and external > + * We only allow VS-mode software, timer, counter overflow and external > * interrupts when irq is one of the local interrupts > * defined by RISC-V privilege specification. > */ > if (irq < IRQ_LOCAL_MAX && > irq != IRQ_VS_SOFT && > irq != IRQ_VS_TIMER && > - irq != IRQ_VS_EXT) > + irq != IRQ_VS_EXT && > + irq != IRQ_PMU_OVF) > return -EINVAL; > > clear_bit(irq, vcpu->arch.irqs_pending); > diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c > index 581568847910..1eaaa919aa61 100644 > --- a/arch/riscv/kvm/vcpu_onereg.c > +++ b/arch/riscv/kvm/vcpu_onereg.c > @@ -36,6 +36,7 @@ static const unsigned long kvm_isa_ext_arr[] = { > /* Multi letter extensions (alphabetically sorted) */ > KVM_ISA_EXT_ARR(SMSTATEEN), > KVM_ISA_EXT_ARR(SSAIA), > + KVM_ISA_EXT_ARR(SSCOFPMF), > KVM_ISA_EXT_ARR(SSTC), > KVM_ISA_EXT_ARR(SVINVAL), > KVM_ISA_EXT_ARR(SVNAPOT), > @@ -88,6 +89,7 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext) > case KVM_RISCV_ISA_EXT_I: > case KVM_RISCV_ISA_EXT_M: > case KVM_RISCV_ISA_EXT_SSTC: > + case KVM_RISCV_ISA_EXT_SSCOFPMF: > case KVM_RISCV_ISA_EXT_SVINVAL: > case KVM_RISCV_ISA_EXT_SVNAPOT: > case KVM_RISCV_ISA_EXT_ZBA: > diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c > index e980235b8436..f2bf5b5bdd61 100644 > --- a/arch/riscv/kvm/vcpu_pmu.c > +++ b/arch/riscv/kvm/vcpu_pmu.c > @@ -229,6 +229,47 @@ 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) > @@ -248,7 +289,7 @@ 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); > @@ -473,6 +514,12 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base, > } > } > > + /* The guest have serviced the interrupt and starting the counter again */ > + if (test_bit(IRQ_PMU_OVF, vcpu->arch.irqs_pending)) { > + clear_bit(pmc_index, kvpmu->pmc_overflown); > + kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_PMU_OVF); > + } > + > out: > retdata->err_val = sbiret; > > @@ -539,7 +586,13 @@ 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 |= (1UL << i); > kvpmu->sdata->ctr_values[i] = pmc->counter_val; > kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, > sizeof(struct riscv_pmu_snapshot_data)); > @@ -548,15 +601,20 @@ 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) { > /* Clear the snapshot area for the upcoming deletion event */ > kvpmu->sdata->ctr_values[i] = 0; > + /* > + * Only clear the given counter as the caller is responsible to > + * validate both the overflow mask and configured counters. > + */ > + kvpmu->sdata->ctr_overflow_mask &= ~(1UL << i); > kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, > sizeof(struct riscv_pmu_snapshot_data)); > } > } > } > - > out: > retdata->err_val = sbiret; > > @@ -699,6 +757,7 @@ 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) > @@ -731,13 +790,14 @@ 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); > } > -- > 2.34.1 >
30.12.2023 00:49, Atish Patra wrote: > > KVM enables perf for guest via counter virtualization. However, the > sampling can not be supported as there is no mechanism to enabled > trap/emulate scountovf in ISA yet. Rely on the SBI PMU snapshot > to provide the counter overflow data via the shared memory. > > In case of sampling event, the host first guest the LCOFI interrupt > and injects to the guest via irq filtering mechanism defined in AIA > specification. Thus, ssaia must be enabled in the host in order to > use perf sampling in the guest. No other AIA dpeendancy w.r.t kernel > is required. > > Signed-off-by: Atish Patra <atishp@rivosinc.com> > --- > arch/riscv/include/asm/csr.h | 3 +- > arch/riscv/include/asm/kvm_vcpu_pmu.h | 1 + > arch/riscv/include/uapi/asm/kvm.h | 1 + > arch/riscv/kvm/main.c | 1 + > arch/riscv/kvm/vcpu.c | 8 +-- > arch/riscv/kvm/vcpu_onereg.c | 2 + > arch/riscv/kvm/vcpu_pmu.c | 70 +++++++++++++++++++++++++-- > 7 files changed, 77 insertions(+), 9 deletions(-) > > diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h > index 88cdc8a3e654..bec09b33e2f0 100644 > --- a/arch/riscv/include/asm/csr.h > +++ b/arch/riscv/include/asm/csr.h > @@ -168,7 +168,8 @@ > #define VSIP_TO_HVIP_SHIFT (IRQ_VS_SOFT - IRQ_S_SOFT) > #define VSIP_VALID_MASK ((_AC(1, UL) << IRQ_S_SOFT) | \ > (_AC(1, UL) << IRQ_S_TIMER) | \ > - (_AC(1, UL) << IRQ_S_EXT)) > + (_AC(1, UL) << IRQ_S_EXT) | \ > + (_AC(1, UL) << IRQ_PMU_OVF)) > > /* AIA CSR bits */ > #define TOPI_IID_SHIFT 16 > diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h > index d56b901a61fc..af6d0ff5ce41 100644 > --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h > +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h > @@ -36,6 +36,7 @@ struct kvm_pmc { > bool started; > /* Monitoring event ID */ > unsigned long event_idx; > + struct kvm_vcpu *vcpu; > }; > > /* PMU data structure per vcpu */ > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h > index d6b7a5b95874..d5aea43bc797 100644 > --- a/arch/riscv/include/uapi/asm/kvm.h > +++ b/arch/riscv/include/uapi/asm/kvm.h > @@ -139,6 +139,7 @@ enum KVM_RISCV_ISA_EXT_ID { > KVM_RISCV_ISA_EXT_ZIHPM, > KVM_RISCV_ISA_EXT_SMSTATEEN, > KVM_RISCV_ISA_EXT_ZICOND, > + KVM_RISCV_ISA_EXT_SSCOFPMF, > KVM_RISCV_ISA_EXT_MAX, > }; > > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c > index 225a435d9c9a..5a3a4cee0e3d 100644 > --- a/arch/riscv/kvm/main.c > +++ b/arch/riscv/kvm/main.c > @@ -43,6 +43,7 @@ int kvm_arch_hardware_enable(void) > csr_write(CSR_HCOUNTEREN, 0x02); > > csr_write(CSR_HVIP, 0); > + csr_write(CSR_HVIEN, 1UL << IRQ_PMU_OVF);\ Hi Atish, Maybe I missed something, but I thought you planned to move CSR_HVIEN to kvm_riscv_aia_enable() and add dependency for KVM sscofpmf and AIA since this register is part of AIA spec. Thank you Vladimir Isaev > > kvm_riscv_aia_enable(); > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index b5ca9f2e98ac..f83f0226439f 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -382,7 +382,8 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > if (irq < IRQ_LOCAL_MAX && > irq != IRQ_VS_SOFT && > irq != IRQ_VS_TIMER && > - irq != IRQ_VS_EXT) > + irq != IRQ_VS_EXT && > + irq != IRQ_PMU_OVF) > return -EINVAL; > > set_bit(irq, vcpu->arch.irqs_pending); > @@ -397,14 +398,15 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > { > /* > - * We only allow VS-mode software, timer, and external > + * We only allow VS-mode software, timer, counter overflow and external > * interrupts when irq is one of the local interrupts > * defined by RISC-V privilege specification. > */ > if (irq < IRQ_LOCAL_MAX && > irq != IRQ_VS_SOFT && > irq != IRQ_VS_TIMER && > - irq != IRQ_VS_EXT) > + irq != IRQ_VS_EXT && > + irq != IRQ_PMU_OVF) > return -EINVAL; > > clear_bit(irq, vcpu->arch.irqs_pending); > diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c > index 581568847910..1eaaa919aa61 100644 > --- a/arch/riscv/kvm/vcpu_onereg.c > +++ b/arch/riscv/kvm/vcpu_onereg.c > @@ -36,6 +36,7 @@ static const unsigned long kvm_isa_ext_arr[] = { > /* Multi letter extensions (alphabetically sorted) */ > KVM_ISA_EXT_ARR(SMSTATEEN), > KVM_ISA_EXT_ARR(SSAIA), > + KVM_ISA_EXT_ARR(SSCOFPMF), > KVM_ISA_EXT_ARR(SSTC), > KVM_ISA_EXT_ARR(SVINVAL), > KVM_ISA_EXT_ARR(SVNAPOT), > @@ -88,6 +89,7 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext) > case KVM_RISCV_ISA_EXT_I: > case KVM_RISCV_ISA_EXT_M: > case KVM_RISCV_ISA_EXT_SSTC: > + case KVM_RISCV_ISA_EXT_SSCOFPMF: > case KVM_RISCV_ISA_EXT_SVINVAL: > case KVM_RISCV_ISA_EXT_SVNAPOT: > case KVM_RISCV_ISA_EXT_ZBA: > diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c > index e980235b8436..f2bf5b5bdd61 100644 > --- a/arch/riscv/kvm/vcpu_pmu.c > +++ b/arch/riscv/kvm/vcpu_pmu.c > @@ -229,6 +229,47 @@ 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) > @@ -248,7 +289,7 @@ 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); > @@ -473,6 +514,12 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base, > } > } > > + /* The guest have serviced the interrupt and starting the counter again */ > + if (test_bit(IRQ_PMU_OVF, vcpu->arch.irqs_pending)) { > + clear_bit(pmc_index, kvpmu->pmc_overflown); > + kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_PMU_OVF); > + } > + > out: > retdata->err_val = sbiret; > > @@ -539,7 +586,13 @@ 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 |= (1UL << i); > kvpmu->sdata->ctr_values[i] = pmc->counter_val; > kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, > sizeof(struct riscv_pmu_snapshot_data)); > @@ -548,15 +601,20 @@ 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) { > /* Clear the snapshot area for the upcoming deletion event */ > kvpmu->sdata->ctr_values[i] = 0; > + /* > + * Only clear the given counter as the caller is responsible to > + * validate both the overflow mask and configured counters. > + */ > + kvpmu->sdata->ctr_overflow_mask &= ~(1UL << i); > kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, > sizeof(struct riscv_pmu_snapshot_data)); > } > } > } > - > out: > retdata->err_val = sbiret; > > @@ -699,6 +757,7 @@ 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) > @@ -731,13 +790,14 @@ 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); > } > -- > 2.34.1 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
On Wed, Jan 10, 2024 at 4:38 AM Vladimir Isaev <vladimir.isaev@syntacore.com> wrote: > > > 30.12.2023 00:49, Atish Patra wrote: > > > > KVM enables perf for guest via counter virtualization. However, the > > sampling can not be supported as there is no mechanism to enabled > > trap/emulate scountovf in ISA yet. Rely on the SBI PMU snapshot > > to provide the counter overflow data via the shared memory. > > > > In case of sampling event, the host first guest the LCOFI interrupt > > and injects to the guest via irq filtering mechanism defined in AIA > > specification. Thus, ssaia must be enabled in the host in order to > > use perf sampling in the guest. No other AIA dpeendancy w.r.t kernel > > is required. > > > > Signed-off-by: Atish Patra <atishp@rivosinc.com> > > --- > > arch/riscv/include/asm/csr.h | 3 +- > > arch/riscv/include/asm/kvm_vcpu_pmu.h | 1 + > > arch/riscv/include/uapi/asm/kvm.h | 1 + > > arch/riscv/kvm/main.c | 1 + > > arch/riscv/kvm/vcpu.c | 8 +-- > > arch/riscv/kvm/vcpu_onereg.c | 2 + > > arch/riscv/kvm/vcpu_pmu.c | 70 +++++++++++++++++++++++++-- > > 7 files changed, 77 insertions(+), 9 deletions(-) > > > > diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h > > index 88cdc8a3e654..bec09b33e2f0 100644 > > --- a/arch/riscv/include/asm/csr.h > > +++ b/arch/riscv/include/asm/csr.h > > @@ -168,7 +168,8 @@ > > #define VSIP_TO_HVIP_SHIFT (IRQ_VS_SOFT - IRQ_S_SOFT) > > #define VSIP_VALID_MASK ((_AC(1, UL) << IRQ_S_SOFT) | \ > > (_AC(1, UL) << IRQ_S_TIMER) | \ > > - (_AC(1, UL) << IRQ_S_EXT)) > > + (_AC(1, UL) << IRQ_S_EXT) | \ > > + (_AC(1, UL) << IRQ_PMU_OVF)) > > > > /* AIA CSR bits */ > > #define TOPI_IID_SHIFT 16 > > diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h > > index d56b901a61fc..af6d0ff5ce41 100644 > > --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h > > +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h > > @@ -36,6 +36,7 @@ struct kvm_pmc { > > bool started; > > /* Monitoring event ID */ > > unsigned long event_idx; > > + struct kvm_vcpu *vcpu; > > }; > > > > /* PMU data structure per vcpu */ > > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h > > index d6b7a5b95874..d5aea43bc797 100644 > > --- a/arch/riscv/include/uapi/asm/kvm.h > > +++ b/arch/riscv/include/uapi/asm/kvm.h > > @@ -139,6 +139,7 @@ enum KVM_RISCV_ISA_EXT_ID { > > KVM_RISCV_ISA_EXT_ZIHPM, > > KVM_RISCV_ISA_EXT_SMSTATEEN, > > KVM_RISCV_ISA_EXT_ZICOND, > > + KVM_RISCV_ISA_EXT_SSCOFPMF, > > KVM_RISCV_ISA_EXT_MAX, > > }; > > > > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c > > index 225a435d9c9a..5a3a4cee0e3d 100644 > > --- a/arch/riscv/kvm/main.c > > +++ b/arch/riscv/kvm/main.c > > @@ -43,6 +43,7 @@ int kvm_arch_hardware_enable(void) > > csr_write(CSR_HCOUNTEREN, 0x02); > > > > csr_write(CSR_HVIP, 0); > > + csr_write(CSR_HVIEN, 1UL << IRQ_PMU_OVF);\ > > Hi Atish, > > Maybe I missed something, but I thought you planned to move CSR_HVIEN to kvm_riscv_aia_enable() and > add dependency for KVM sscofpmf and AIA since this register is part of AIA spec. > I already did that in the previous patch. https://lore.kernel.org/all/20231229214950.4061381-9-atishp@rivosinc.com/ I am not sure how this line got into this patch. My bad! Thanks for noticing it. I will send a fixed version right away. > Thank you > Vladimir Isaev > > > > > kvm_riscv_aia_enable(); > > > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > > index b5ca9f2e98ac..f83f0226439f 100644 > > --- a/arch/riscv/kvm/vcpu.c > > +++ b/arch/riscv/kvm/vcpu.c > > @@ -382,7 +382,8 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > > if (irq < IRQ_LOCAL_MAX && > > irq != IRQ_VS_SOFT && > > irq != IRQ_VS_TIMER && > > - irq != IRQ_VS_EXT) > > + irq != IRQ_VS_EXT && > > + irq != IRQ_PMU_OVF) > > return -EINVAL; > > > > set_bit(irq, vcpu->arch.irqs_pending); > > @@ -397,14 +398,15 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > > int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > > { > > /* > > - * We only allow VS-mode software, timer, and external > > + * We only allow VS-mode software, timer, counter overflow and external > > * interrupts when irq is one of the local interrupts > > * defined by RISC-V privilege specification. > > */ > > if (irq < IRQ_LOCAL_MAX && > > irq != IRQ_VS_SOFT && > > irq != IRQ_VS_TIMER && > > - irq != IRQ_VS_EXT) > > + irq != IRQ_VS_EXT && > > + irq != IRQ_PMU_OVF) > > return -EINVAL; > > > > clear_bit(irq, vcpu->arch.irqs_pending); > > diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c > > index 581568847910..1eaaa919aa61 100644 > > --- a/arch/riscv/kvm/vcpu_onereg.c > > +++ b/arch/riscv/kvm/vcpu_onereg.c > > @@ -36,6 +36,7 @@ static const unsigned long kvm_isa_ext_arr[] = { > > /* Multi letter extensions (alphabetically sorted) */ > > KVM_ISA_EXT_ARR(SMSTATEEN), > > KVM_ISA_EXT_ARR(SSAIA), > > + KVM_ISA_EXT_ARR(SSCOFPMF), > > KVM_ISA_EXT_ARR(SSTC), > > KVM_ISA_EXT_ARR(SVINVAL), > > KVM_ISA_EXT_ARR(SVNAPOT), > > @@ -88,6 +89,7 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext) > > case KVM_RISCV_ISA_EXT_I: > > case KVM_RISCV_ISA_EXT_M: > > case KVM_RISCV_ISA_EXT_SSTC: > > + case KVM_RISCV_ISA_EXT_SSCOFPMF: > > case KVM_RISCV_ISA_EXT_SVINVAL: > > case KVM_RISCV_ISA_EXT_SVNAPOT: > > case KVM_RISCV_ISA_EXT_ZBA: > > diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c > > index e980235b8436..f2bf5b5bdd61 100644 > > --- a/arch/riscv/kvm/vcpu_pmu.c > > +++ b/arch/riscv/kvm/vcpu_pmu.c > > @@ -229,6 +229,47 @@ 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) > > @@ -248,7 +289,7 @@ 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); > > @@ -473,6 +514,12 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base, > > } > > } > > > > + /* The guest have serviced the interrupt and starting the counter again */ > > + if (test_bit(IRQ_PMU_OVF, vcpu->arch.irqs_pending)) { > > + clear_bit(pmc_index, kvpmu->pmc_overflown); > > + kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_PMU_OVF); > > + } > > + > > out: > > retdata->err_val = sbiret; > > > > @@ -539,7 +586,13 @@ 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 |= (1UL << i); > > kvpmu->sdata->ctr_values[i] = pmc->counter_val; > > kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, > > sizeof(struct riscv_pmu_snapshot_data)); > > @@ -548,15 +601,20 @@ 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) { > > /* Clear the snapshot area for the upcoming deletion event */ > > kvpmu->sdata->ctr_values[i] = 0; > > + /* > > + * Only clear the given counter as the caller is responsible to > > + * validate both the overflow mask and configured counters. > > + */ > > + kvpmu->sdata->ctr_overflow_mask &= ~(1UL << i); > > kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, > > sizeof(struct riscv_pmu_snapshot_data)); > > } > > } > > } > > - > > out: > > retdata->err_val = sbiret; > > > > @@ -699,6 +757,7 @@ 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) > > @@ -731,13 +790,14 @@ 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); > > } > > -- > > 2.34.1 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h index 88cdc8a3e654..bec09b33e2f0 100644 --- a/arch/riscv/include/asm/csr.h +++ b/arch/riscv/include/asm/csr.h @@ -168,7 +168,8 @@ #define VSIP_TO_HVIP_SHIFT (IRQ_VS_SOFT - IRQ_S_SOFT) #define VSIP_VALID_MASK ((_AC(1, UL) << IRQ_S_SOFT) | \ (_AC(1, UL) << IRQ_S_TIMER) | \ - (_AC(1, UL) << IRQ_S_EXT)) + (_AC(1, UL) << IRQ_S_EXT) | \ + (_AC(1, UL) << IRQ_PMU_OVF)) /* AIA CSR bits */ #define TOPI_IID_SHIFT 16 diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h index d56b901a61fc..af6d0ff5ce41 100644 --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h @@ -36,6 +36,7 @@ struct kvm_pmc { bool started; /* Monitoring event ID */ unsigned long event_idx; + struct kvm_vcpu *vcpu; }; /* PMU data structure per vcpu */ diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h index d6b7a5b95874..d5aea43bc797 100644 --- a/arch/riscv/include/uapi/asm/kvm.h +++ b/arch/riscv/include/uapi/asm/kvm.h @@ -139,6 +139,7 @@ enum KVM_RISCV_ISA_EXT_ID { KVM_RISCV_ISA_EXT_ZIHPM, KVM_RISCV_ISA_EXT_SMSTATEEN, KVM_RISCV_ISA_EXT_ZICOND, + KVM_RISCV_ISA_EXT_SSCOFPMF, KVM_RISCV_ISA_EXT_MAX, }; diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c index 225a435d9c9a..5a3a4cee0e3d 100644 --- a/arch/riscv/kvm/main.c +++ b/arch/riscv/kvm/main.c @@ -43,6 +43,7 @@ int kvm_arch_hardware_enable(void) csr_write(CSR_HCOUNTEREN, 0x02); csr_write(CSR_HVIP, 0); + csr_write(CSR_HVIEN, 1UL << IRQ_PMU_OVF); kvm_riscv_aia_enable(); diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index b5ca9f2e98ac..f83f0226439f 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -382,7 +382,8 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) if (irq < IRQ_LOCAL_MAX && irq != IRQ_VS_SOFT && irq != IRQ_VS_TIMER && - irq != IRQ_VS_EXT) + irq != IRQ_VS_EXT && + irq != IRQ_PMU_OVF) return -EINVAL; set_bit(irq, vcpu->arch.irqs_pending); @@ -397,14 +398,15 @@ int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) { /* - * We only allow VS-mode software, timer, and external + * We only allow VS-mode software, timer, counter overflow and external * interrupts when irq is one of the local interrupts * defined by RISC-V privilege specification. */ if (irq < IRQ_LOCAL_MAX && irq != IRQ_VS_SOFT && irq != IRQ_VS_TIMER && - irq != IRQ_VS_EXT) + irq != IRQ_VS_EXT && + irq != IRQ_PMU_OVF) return -EINVAL; clear_bit(irq, vcpu->arch.irqs_pending); diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c index 581568847910..1eaaa919aa61 100644 --- a/arch/riscv/kvm/vcpu_onereg.c +++ b/arch/riscv/kvm/vcpu_onereg.c @@ -36,6 +36,7 @@ static const unsigned long kvm_isa_ext_arr[] = { /* Multi letter extensions (alphabetically sorted) */ KVM_ISA_EXT_ARR(SMSTATEEN), KVM_ISA_EXT_ARR(SSAIA), + KVM_ISA_EXT_ARR(SSCOFPMF), KVM_ISA_EXT_ARR(SSTC), KVM_ISA_EXT_ARR(SVINVAL), KVM_ISA_EXT_ARR(SVNAPOT), @@ -88,6 +89,7 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext) case KVM_RISCV_ISA_EXT_I: case KVM_RISCV_ISA_EXT_M: case KVM_RISCV_ISA_EXT_SSTC: + case KVM_RISCV_ISA_EXT_SSCOFPMF: case KVM_RISCV_ISA_EXT_SVINVAL: case KVM_RISCV_ISA_EXT_SVNAPOT: case KVM_RISCV_ISA_EXT_ZBA: diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c index e980235b8436..f2bf5b5bdd61 100644 --- a/arch/riscv/kvm/vcpu_pmu.c +++ b/arch/riscv/kvm/vcpu_pmu.c @@ -229,6 +229,47 @@ 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) @@ -248,7 +289,7 @@ 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); @@ -473,6 +514,12 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base, } } + /* The guest have serviced the interrupt and starting the counter again */ + if (test_bit(IRQ_PMU_OVF, vcpu->arch.irqs_pending)) { + clear_bit(pmc_index, kvpmu->pmc_overflown); + kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_PMU_OVF); + } + out: retdata->err_val = sbiret; @@ -539,7 +586,13 @@ 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 |= (1UL << i); kvpmu->sdata->ctr_values[i] = pmc->counter_val; kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, sizeof(struct riscv_pmu_snapshot_data)); @@ -548,15 +601,20 @@ 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) { /* Clear the snapshot area for the upcoming deletion event */ kvpmu->sdata->ctr_values[i] = 0; + /* + * Only clear the given counter as the caller is responsible to + * validate both the overflow mask and configured counters. + */ + kvpmu->sdata->ctr_overflow_mask &= ~(1UL << i); kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata, sizeof(struct riscv_pmu_snapshot_data)); } } } - out: retdata->err_val = sbiret; @@ -699,6 +757,7 @@ 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) @@ -731,13 +790,14 @@ 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); }
KVM enables perf for guest via counter virtualization. However, the sampling can not be supported as there is no mechanism to enabled trap/emulate scountovf in ISA yet. Rely on the SBI PMU snapshot to provide the counter overflow data via the shared memory. In case of sampling event, the host first guest the LCOFI interrupt and injects to the guest via irq filtering mechanism defined in AIA specification. Thus, ssaia must be enabled in the host in order to use perf sampling in the guest. No other AIA dpeendancy w.r.t kernel is required. Signed-off-by: Atish Patra <atishp@rivosinc.com> --- arch/riscv/include/asm/csr.h | 3 +- arch/riscv/include/asm/kvm_vcpu_pmu.h | 1 + arch/riscv/include/uapi/asm/kvm.h | 1 + arch/riscv/kvm/main.c | 1 + arch/riscv/kvm/vcpu.c | 8 +-- arch/riscv/kvm/vcpu_onereg.c | 2 + arch/riscv/kvm/vcpu_pmu.c | 70 +++++++++++++++++++++++++-- 7 files changed, 77 insertions(+), 9 deletions(-)