Re: [PATCH v3 13/14] RISC-V: KVM: Support firmware events

From: Anup Patel
Date: Mon Jan 30 2023 - 10:47:52 EST

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In reply to: Atish Patra: "[PATCH v3 13/14] RISC-V: KVM: Support firmware events"
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On Fri, Jan 27, 2023 at 11:56 PM Atish Patra <atishp@xxxxxxxxxxxx> wrote:
>
> SBI PMU extension defines a set of firmware events which can provide
> useful information to guests about number of SBI calls. As hypervisor

s/about number/about the number/

> implements the SBI PMU extension, these firmware events corresponds

s/corresponds/correspond/

> to ecall invocations between VS->HS mode. All other firmware events
> will always report zero if monitored as KVM doesn't implement them.
>
> This patch adds all the infrastructure required to support firmware
> events.
>
> Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>

Otherwise, it looks good to me.

Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>

Regards,
Anup

> ---
> arch/riscv/include/asm/kvm_vcpu_pmu.h | 16 +++
> arch/riscv/kvm/vcpu_pmu.c | 144 +++++++++++++++++++-------
> 2 files changed, 124 insertions(+), 36 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> index 022d45d..b235e7e 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> @@ -17,6 +17,14 @@
> #define RISCV_KVM_MAX_FW_CTRS 32
> #define RISCV_MAX_COUNTERS 64
>
> +struct kvm_fw_event {
> + /* Current value of the event */
> + unsigned long value;
> +
> + /* Event monitoring status */
> + bool started;
> +};
> +
> /* Per virtual pmu counter data */
> struct kvm_pmc {
> u8 idx;
> @@ -25,11 +33,14 @@ struct kvm_pmc {
> union sbi_pmu_ctr_info cinfo;
> /* Event monitoring status */
> bool started;
> + /* Monitoring event ID */
> + unsigned long event_idx;
> };
>
> /* PMU data structure per vcpu */
> struct kvm_pmu {
> struct kvm_pmc pmc[RISCV_MAX_COUNTERS];
> + struct kvm_fw_event fw_event[RISCV_KVM_MAX_FW_CTRS];
> /* Number of the virtual firmware counters available */
> int num_fw_ctrs;
> /* Number of the virtual hardware counters available */
> @@ -52,6 +63,7 @@ struct kvm_pmu {
> { .base = CSR_CYCLE, .count = 31, .func = kvm_riscv_vcpu_pmu_read_hpm },
> #endif
>
> +int kvm_riscv_vcpu_pmu_incr_fw(struct kvm_vcpu *vcpu, unsigned long fid);
> int kvm_riscv_vcpu_pmu_read_hpm(struct kvm_vcpu *vcpu, unsigned int csr_num,
> unsigned long *val, unsigned long new_val,
> unsigned long wr_mask);
> @@ -81,6 +93,10 @@ struct kvm_pmu {
> #define KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS \
> { .base = 0, .count = 0, .func = NULL },
>
> +static inline int kvm_riscv_vcpu_pmu_incr_fw(struct kvm_vcpu *vcpu, unsigned long fid)
> +{
> + return 0;
> +}
>
> static inline int kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
> {
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> index 73dccf7..b8d6aba 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -203,12 +203,15 @@ static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
> struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> struct kvm_pmc *pmc;
> u64 enabled, running;
> + int fevent_code;
>
> pmc = &kvpmu->pmc[cidx];
> - if (!pmc->perf_event)
> - return -EINVAL;
>
> - pmc->counter_val += perf_event_read_value(pmc->perf_event, &enabled, &running);
> + if (pmc->cinfo.type == SBI_PMU_CTR_TYPE_FW) {
> + fevent_code = get_event_code(pmc->event_idx);
> + pmc->counter_val = kvpmu->fw_event[fevent_code].value;
> + } else if (pmc->perf_event)
> + pmc->counter_val += perf_event_read_value(pmc->perf_event, &enabled, &running);
> *out_val = pmc->counter_val;
>
> return 0;
> @@ -224,6 +227,55 @@ static int kvm_pmu_validate_counter_mask(struct kvm_pmu *kvpmu, unsigned long ct
> return 0;
> }
>
> +static int kvm_pmu_create_perf_event(struct kvm_pmc *pmc, int ctr_idx,
> + struct perf_event_attr *attr, unsigned long flag,
> + unsigned long eidx, unsigned long evtdata)
> +{
> + struct perf_event *event;
> +
> + kvm_pmu_release_perf_event(pmc);
> + pmc->idx = ctr_idx;
> +
> + attr->config = kvm_pmu_get_perf_event_config(eidx, evtdata);
> + if (flag & SBI_PMU_CFG_FLAG_CLEAR_VALUE) {
> + //TODO: Do we really want to clear the value in hardware counter
> + pmc->counter_val = 0;
> + }
> +
> + /*
> + * Set the default sample_period for now. The guest specified value
> + * will be updated in the start call.
> + */
> + attr->sample_period = kvm_pmu_get_sample_period(pmc);
> +
> + event = perf_event_create_kernel_counter(attr, -1, current, NULL, 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);
> + }
> +
> + pmc->perf_event = event;
> + if (flag & SBI_PMU_CFG_FLAG_AUTO_START)
> + perf_event_enable(pmc->perf_event);
> +
> + return 0;
> +}
> +
> +int kvm_riscv_vcpu_pmu_incr_fw(struct kvm_vcpu *vcpu, unsigned long fid)
> +{
> + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> + struct kvm_fw_event *fevent;
> +
> + if (!kvpmu || fid >= SBI_PMU_FW_MAX)
> + return -EINVAL;
> +
> + fevent = &kvpmu->fw_event[fid];
> + if (fevent->started)
> + fevent->value++;
> +
> + return 0;
> +}
> +
> int kvm_riscv_vcpu_pmu_read_hpm(struct kvm_vcpu *vcpu, unsigned int csr_num,
> unsigned long *val, unsigned long new_val,
> unsigned long wr_mask)
> @@ -276,6 +328,7 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> int i, pmc_index, sbiret = 0;
> struct kvm_pmc *pmc;
> + int fevent_code;
>
> if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
> sbiret = SBI_ERR_INVALID_PARAM;
> @@ -290,7 +343,22 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> pmc = &kvpmu->pmc[pmc_index];
> if (flag & SBI_PMU_START_FLAG_SET_INIT_VALUE)
> pmc->counter_val = ival;
> - if (pmc->perf_event) {
> + if (pmc->cinfo.type == SBI_PMU_CTR_TYPE_FW) {
> + fevent_code = get_event_code(pmc->event_idx);
> + if (fevent_code >= SBI_PMU_FW_MAX) {
> + sbiret = SBI_ERR_INVALID_PARAM;
> + goto out;
> + }
> +
> + /* Check if the counter was already started for some reason */
> + if (kvpmu->fw_event[fevent_code].started) {
> + sbiret = SBI_ERR_ALREADY_STARTED;
> + continue;
> + }
> +
> + kvpmu->fw_event[fevent_code].started = true;
> + kvpmu->fw_event[fevent_code].value = pmc->counter_val;
> + } else if (pmc->perf_event) {
> if (unlikely(pmc->started)) {
> sbiret = SBI_ERR_ALREADY_STARTED;
> continue;
> @@ -317,6 +385,7 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> int i, pmc_index, sbiret = 0;
> u64 enabled, running;
> struct kvm_pmc *pmc;
> + int fevent_code;
>
> if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
> sbiret = SBI_ERR_INVALID_PARAM;
> @@ -329,7 +398,18 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> if (!test_bit(pmc_index, kvpmu->pmc_in_use))
> continue;
> pmc = &kvpmu->pmc[pmc_index];
> - if (pmc->perf_event) {
> + if (pmc->cinfo.type == SBI_PMU_CTR_TYPE_FW) {
> + fevent_code = get_event_code(pmc->event_idx);
> + if (fevent_code >= SBI_PMU_FW_MAX) {
> + sbiret = SBI_ERR_INVALID_PARAM;
> + goto out;
> + }
> +
> + if (!kvpmu->fw_event[fevent_code].started)
> + sbiret = SBI_ERR_ALREADY_STOPPED;
> +
> + kvpmu->fw_event[fevent_code].started = false;
> + } else if (pmc->perf_event) {
> if (pmc->started) {
> /* Stop counting the counter */
> perf_event_disable(pmc->perf_event);
> @@ -342,11 +422,14 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> pmc->counter_val += perf_event_read_value(pmc->perf_event,
> &enabled, &running);
> kvm_pmu_release_perf_event(pmc);
> - clear_bit(pmc_index, kvpmu->pmc_in_use);
> }
> } else {
> sbiret = SBI_ERR_INVALID_PARAM;
> }
> + if (flag & SBI_PMU_STOP_FLAG_RESET) {
> + pmc->event_idx = SBI_PMU_EVENT_IDX_INVALID;
> + clear_bit(pmc_index, kvpmu->pmc_in_use);
> + }
> }
>
> out:
> @@ -361,12 +444,11 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
> struct kvm_vcpu_sbi_ext_data *edata)
> {
> struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> - struct perf_event *event;
> - int ctr_idx;
> + int ctr_idx, sbiret = 0, ret;
> u32 etype = kvm_pmu_get_perf_event_type(eidx);
> - u64 config;
> - struct kvm_pmc *pmc;
> - int sbiret = 0;
> + struct kvm_pmc *pmc = NULL;
> + bool is_fevent;
> + unsigned long event_code;
> struct perf_event_attr attr = {
> .type = etype,
> .size = sizeof(struct perf_event_attr),
> @@ -387,7 +469,9 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
> goto out;
> }
>
> - if (kvm_pmu_is_fw_event(eidx)) {
> + event_code = get_event_code(eidx);
> + is_fevent = kvm_pmu_is_fw_event(eidx);
> + if (is_fevent && event_code >= SBI_PMU_FW_MAX) {
> sbiret = SBI_ERR_NOT_SUPPORTED;
> goto out;
> }
> @@ -412,33 +496,17 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
> }
>
> pmc = &kvpmu->pmc[ctr_idx];
> - kvm_pmu_release_perf_event(pmc);
> - pmc->idx = ctr_idx;
> -
> - config = kvm_pmu_get_perf_event_config(eidx, evtdata);
> - attr.config = config;
> - if (flag & SBI_PMU_CFG_FLAG_CLEAR_VALUE) {
> - //TODO: Do we really want to clear the value in hardware counter
> - pmc->counter_val = 0;
> - }
> -
> - /*
> - * Set the default sample_period for now. The guest specified value
> - * will be updated in the start call.
> - */
> - attr.sample_period = kvm_pmu_get_sample_period(pmc);
> -
> - event = perf_event_create_kernel_counter(&attr, -1, current, NULL, 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);
> + if (is_fevent) {
> + if (flag & SBI_PMU_CFG_FLAG_AUTO_START)
> + kvpmu->fw_event[event_code].started = true;
> + } else {
> + ret = kvm_pmu_create_perf_event(pmc, ctr_idx, &attr, flag, eidx, evtdata);
> + if (ret)
> + return ret;
> }
>
> set_bit(ctr_idx, kvpmu->pmc_in_use);
> - pmc->perf_event = event;
> - if (flag & SBI_PMU_CFG_FLAG_AUTO_START)
> - perf_event_enable(pmc->perf_event);
> -
> + pmc->event_idx = eidx;
> edata->out_val = ctr_idx;
> out:
> edata->err_val = sbiret;
> @@ -489,6 +557,7 @@ int kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
>
> kvpmu->num_hw_ctrs = num_hw_ctrs;
> kvpmu->num_fw_ctrs = num_fw_ctrs;
> + memset(&kvpmu->fw_event, 0, SBI_PMU_FW_MAX * sizeof(struct kvm_fw_event));
>
> /*
> * There is no correlation between the logical hardware counter and virtual counters.
> @@ -502,6 +571,7 @@ int kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
> continue;
> pmc = &kvpmu->pmc[i];
> pmc->idx = i;
> + pmc->event_idx = SBI_PMU_EVENT_IDX_INVALID;
> if (i < kvpmu->num_hw_ctrs) {
> kvpmu->pmc[i].cinfo.type = SBI_PMU_CTR_TYPE_HW;
> if (i < 3)
> @@ -540,8 +610,10 @@ void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu)
> 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);
> + memset(&kvpmu->fw_event, 0, SBI_PMU_FW_MAX * sizeof(struct kvm_fw_event));
> }
>
> void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu)
> --
> 2.25.1
>

Next message: Anup Patel: "Re: [PATCH v3 14/14] RISC-V: KVM: Increment firmware pmu events"
Previous message: Thierry Reding: "Re: (subset) [PATCH v1 0/2] pwm-mediatek: Convert to schema and fixes"
In reply to: Atish Patra: "[PATCH v3 13/14] RISC-V: KVM: Support firmware events"
Next in thread: Atish Patra: "[PATCH v3 14/14] RISC-V: KVM: Increment firmware pmu events"
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