[PATCH v4 12/14] RISC-V: KVM: Implement perf support without sampling
Atish Patra
atishp at rivosinc.com
Wed Feb 1 15:12:48 PST 2023
RISC-V SBI PMU & Sscofpmf ISA extension allows supporting perf in
the virtualization enviornment as well. KVM implementation
relies on SBI PMU extension for the most part while trapping
& emulating the CSRs read for counter access.
This patch doesn't have the event sampling support yet.
Reviewed-by: Anup Patel <anup at brainfault.org>
Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
arch/riscv/kvm/vcpu_pmu.c | 360 +++++++++++++++++++++++++++++++++++++-
1 file changed, 356 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 6fa0065..473ad80 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -12,10 +12,189 @@
#include <linux/perf/riscv_pmu.h>
#include <asm/csr.h>
#include <asm/kvm_vcpu_sbi.h>
+#include <asm/bitops.h>
#include <asm/kvm_vcpu_pmu.h>
#include <linux/kvm_host.h>
#define kvm_pmu_num_counters(pmu) ((pmu)->num_hw_ctrs + (pmu)->num_fw_ctrs)
+#define get_event_type(x) (((x) & SBI_PMU_EVENT_IDX_TYPE_MASK) >> 16)
+#define get_event_code(x) ((x) & SBI_PMU_EVENT_IDX_CODE_MASK)
+
+static enum perf_hw_id hw_event_perf_map[SBI_PMU_HW_GENERAL_MAX] = {
+ [SBI_PMU_HW_CPU_CYCLES] = PERF_COUNT_HW_CPU_CYCLES,
+ [SBI_PMU_HW_INSTRUCTIONS] = PERF_COUNT_HW_INSTRUCTIONS,
+ [SBI_PMU_HW_CACHE_REFERENCES] = PERF_COUNT_HW_CACHE_REFERENCES,
+ [SBI_PMU_HW_CACHE_MISSES] = PERF_COUNT_HW_CACHE_MISSES,
+ [SBI_PMU_HW_BRANCH_INSTRUCTIONS] = PERF_COUNT_HW_BRANCH_INSTRUCTIONS,
+ [SBI_PMU_HW_BRANCH_MISSES] = PERF_COUNT_HW_BRANCH_MISSES,
+ [SBI_PMU_HW_BUS_CYCLES] = PERF_COUNT_HW_BUS_CYCLES,
+ [SBI_PMU_HW_STALLED_CYCLES_FRONTEND] = PERF_COUNT_HW_STALLED_CYCLES_FRONTEND,
+ [SBI_PMU_HW_STALLED_CYCLES_BACKEND] = PERF_COUNT_HW_STALLED_CYCLES_BACKEND,
+ [SBI_PMU_HW_REF_CPU_CYCLES] = PERF_COUNT_HW_REF_CPU_CYCLES,
+};
+
+static u64 kvm_pmu_get_sample_period(struct kvm_pmc *pmc)
+{
+ u64 counter_val_mask = GENMASK(pmc->cinfo.width, 0);
+ u64 sample_period;
+
+ if (!pmc->counter_val)
+ sample_period = counter_val_mask + 1;
+ else
+ sample_period = (-pmc->counter_val) & counter_val_mask;
+
+ return sample_period;
+}
+
+static u32 kvm_pmu_get_perf_event_type(unsigned long eidx)
+{
+ enum sbi_pmu_event_type etype = get_event_type(eidx);
+ u32 type = PERF_TYPE_MAX;
+
+ switch (etype) {
+ case SBI_PMU_EVENT_TYPE_HW:
+ type = PERF_TYPE_HARDWARE;
+ break;
+ case SBI_PMU_EVENT_TYPE_CACHE:
+ type = PERF_TYPE_HW_CACHE;
+ break;
+ case SBI_PMU_EVENT_TYPE_RAW:
+ case SBI_PMU_EVENT_TYPE_FW:
+ type = PERF_TYPE_RAW;
+ break;
+ default:
+ break;
+ }
+
+ return type;
+}
+
+static bool kvm_pmu_is_fw_event(unsigned long eidx)
+{
+ return get_event_type(eidx) == SBI_PMU_EVENT_TYPE_FW;
+}
+
+static void kvm_pmu_release_perf_event(struct kvm_pmc *pmc)
+{
+ if (pmc->perf_event) {
+ perf_event_disable(pmc->perf_event);
+ perf_event_release_kernel(pmc->perf_event);
+ pmc->perf_event = NULL;
+ }
+}
+
+static u64 kvm_pmu_get_perf_event_hw_config(u32 sbi_event_code)
+{
+ return hw_event_perf_map[sbi_event_code];
+}
+
+static u64 kvm_pmu_get_perf_event_cache_config(u32 sbi_event_code)
+{
+ u64 config = U64_MAX;
+ unsigned int cache_type, cache_op, cache_result;
+
+ /* All the cache event masks lie within 0xFF. No separate masking is necessary */
+ cache_type = (sbi_event_code & SBI_PMU_EVENT_CACHE_ID_CODE_MASK) >>
+ SBI_PMU_EVENT_CACHE_ID_SHIFT;
+ cache_op = (sbi_event_code & SBI_PMU_EVENT_CACHE_OP_ID_CODE_MASK) >>
+ SBI_PMU_EVENT_CACHE_OP_SHIFT;
+ cache_result = sbi_event_code & SBI_PMU_EVENT_CACHE_RESULT_ID_CODE_MASK;
+
+ if (cache_type >= PERF_COUNT_HW_CACHE_MAX ||
+ cache_op >= PERF_COUNT_HW_CACHE_OP_MAX ||
+ cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+ return config;
+
+ config = cache_type | (cache_op << 8) | (cache_result << 16);
+
+ return config;
+}
+
+static u64 kvm_pmu_get_perf_event_config(unsigned long eidx, uint64_t evt_data)
+{
+ enum sbi_pmu_event_type etype = get_event_type(eidx);
+ u32 ecode = get_event_code(eidx);
+ u64 config = U64_MAX;
+
+ switch (etype) {
+ case SBI_PMU_EVENT_TYPE_HW:
+ if (ecode < SBI_PMU_HW_GENERAL_MAX)
+ config = kvm_pmu_get_perf_event_hw_config(ecode);
+ break;
+ case SBI_PMU_EVENT_TYPE_CACHE:
+ config = kvm_pmu_get_perf_event_cache_config(ecode);
+ break;
+ case SBI_PMU_EVENT_TYPE_RAW:
+ config = evt_data & RISCV_PMU_RAW_EVENT_MASK;
+ break;
+ case SBI_PMU_EVENT_TYPE_FW:
+ if (ecode < SBI_PMU_FW_MAX)
+ config = (1ULL << 63) | ecode;
+ break;
+ default:
+ break;
+ }
+
+ return config;
+}
+
+static int kvm_pmu_get_fixed_pmc_index(unsigned long eidx)
+{
+ u32 etype = kvm_pmu_get_perf_event_type(eidx);
+ u32 ecode = get_event_code(eidx);
+
+ if (etype != SBI_PMU_EVENT_TYPE_HW)
+ return -EINVAL;
+
+ if (ecode == SBI_PMU_HW_CPU_CYCLES)
+ return 0;
+ else if (ecode == SBI_PMU_HW_INSTRUCTIONS)
+ return 2;
+ else
+ return -EINVAL;
+}
+
+static int kvm_pmu_get_programmable_pmc_index(struct kvm_pmu *kvpmu, unsigned long eidx,
+ unsigned long cbase, unsigned long cmask)
+{
+ int ctr_idx = -1;
+ int i, pmc_idx;
+ int min, max;
+
+ if (kvm_pmu_is_fw_event(eidx)) {
+ /* Firmware counters are mapped 1:1 starting from num_hw_ctrs for simplicity */
+ min = kvpmu->num_hw_ctrs;
+ max = min + kvpmu->num_fw_ctrs;
+ } else {
+ /* First 3 counters are reserved for fixed counters */
+ min = 3;
+ max = kvpmu->num_hw_ctrs;
+ }
+
+ for_each_set_bit(i, &cmask, BITS_PER_LONG) {
+ pmc_idx = i + cbase;
+ if ((pmc_idx >= min && pmc_idx < max) &&
+ !test_bit(pmc_idx, kvpmu->pmc_in_use)) {
+ ctr_idx = pmc_idx;
+ break;
+ }
+ }
+
+ return ctr_idx;
+}
+
+static int pmu_get_pmc_index(struct kvm_pmu *pmu, unsigned long eidx,
+ unsigned long cbase, unsigned long cmask)
+{
+ int ret;
+
+ /* Fixed counters need to be have fixed mapping as they have different width */
+ ret = kvm_pmu_get_fixed_pmc_index(eidx);
+ if (ret >= 0)
+ return ret;
+
+ return kvm_pmu_get_programmable_pmc_index(pmu, eidx, cbase, cmask);
+}
static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
unsigned long *out_val)
@@ -34,6 +213,16 @@ static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
return 0;
}
+static int kvm_pmu_validate_counter_mask(struct kvm_pmu *kvpmu, unsigned long ctr_base,
+ unsigned long ctr_mask)
+{
+ /* Make sure the we have a valid counter mask requested from the caller */
+ if (!ctr_mask || (ctr_base + __fls(ctr_mask) >= kvm_pmu_num_counters(kvpmu)))
+ return -EINVAL;
+
+ 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)
@@ -97,7 +286,39 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base,
unsigned long ctr_mask, unsigned long flag, uint64_t ival,
struct kvm_vcpu_sbi_return *retdata)
{
- /* TODO */
+ struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+ int i, pmc_index, sbiret = 0;
+ struct kvm_pmc *pmc;
+
+ if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
+ sbiret = SBI_ERR_INVALID_PARAM;
+ goto out;
+ }
+
+ /* Start the counters that have been configured and requested by the guest */
+ for_each_set_bit(i, &ctr_mask, RISCV_MAX_COUNTERS) {
+ pmc_index = i + ctr_base;
+ if (!test_bit(pmc_index, kvpmu->pmc_in_use))
+ continue;
+ pmc = &kvpmu->pmc[pmc_index];
+ if (flag & SBI_PMU_START_FLAG_SET_INIT_VALUE)
+ pmc->counter_val = ival;
+ if (pmc->perf_event) {
+ if (unlikely(pmc->started)) {
+ sbiret = SBI_ERR_ALREADY_STARTED;
+ continue;
+ }
+ perf_event_period(pmc->perf_event, kvm_pmu_get_sample_period(pmc));
+ perf_event_enable(pmc->perf_event);
+ pmc->started = true;
+ } else {
+ sbiret = SBI_ERR_INVALID_PARAM;
+ }
+ }
+
+out:
+ retdata->err_val = sbiret;
+
return 0;
}
@@ -105,7 +326,45 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
unsigned long ctr_mask, unsigned long flag,
struct kvm_vcpu_sbi_return *retdata)
{
- /* TODO */
+ struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+ int i, pmc_index, sbiret = 0;
+ u64 enabled, running;
+ struct kvm_pmc *pmc;
+
+ if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
+ sbiret = SBI_ERR_INVALID_PARAM;
+ goto out;
+ }
+
+ /* Stop the counters that have been configured and requested by the guest */
+ for_each_set_bit(i, &ctr_mask, RISCV_MAX_COUNTERS) {
+ pmc_index = i + ctr_base;
+ if (!test_bit(pmc_index, kvpmu->pmc_in_use))
+ continue;
+ pmc = &kvpmu->pmc[pmc_index];
+ if (pmc->perf_event) {
+ if (pmc->started) {
+ /* Stop counting the counter */
+ perf_event_disable(pmc->perf_event);
+ pmc->started = false;
+ } else
+ sbiret = SBI_ERR_ALREADY_STOPPED;
+
+ if (flag & SBI_PMU_STOP_FLAG_RESET) {
+ /* Relase the counter if this is a reset request */
+ 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;
+ }
+ }
+
+out:
+ retdata->err_val = sbiret;
+
return 0;
}
@@ -114,7 +373,88 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
unsigned long eidx, uint64_t evtdata,
struct kvm_vcpu_sbi_return *retdata)
{
- /* TODO */
+ int ctr_idx, sbiret = 0;
+ u64 config;
+ u32 etype = kvm_pmu_get_perf_event_type(eidx);
+ struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+ struct perf_event *event;
+ struct kvm_pmc *pmc;
+ struct perf_event_attr attr = {
+ .type = etype,
+ .size = sizeof(struct perf_event_attr),
+ .pinned = true,
+ /*
+ * It should never reach here if the platform doesn't support the sscofpmf
+ * extension as mode filtering won't work without it.
+ */
+ .exclude_host = true,
+ .exclude_hv = true,
+ .exclude_user = !!(flag & SBI_PMU_CFG_FLAG_SET_UINH),
+ .exclude_kernel = !!(flag & SBI_PMU_CFG_FLAG_SET_SINH),
+ .config1 = RISCV_PMU_CONFIG1_GUEST_EVENTS,
+ };
+
+ if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
+ sbiret = SBI_ERR_INVALID_PARAM;
+ goto out;
+ }
+
+ if (kvm_pmu_is_fw_event(eidx)) {
+ sbiret = SBI_ERR_NOT_SUPPORTED;
+ goto out;
+ }
+
+ /*
+ * SKIP_MATCH flag indicates the caller is aware of the assigned counter
+ * for this event. Just do a sanity check if it already marked used.
+ */
+ if (flag & SBI_PMU_CFG_FLAG_SKIP_MATCH) {
+ if (!test_bit(ctr_base + __ffs(ctr_mask), kvpmu->pmc_in_use)) {
+ sbiret = SBI_ERR_FAILURE;
+ goto out;
+ }
+ ctr_idx = ctr_base + __ffs(ctr_mask);
+ } else {
+
+ ctr_idx = pmu_get_pmc_index(kvpmu, eidx, ctr_base, ctr_mask);
+ if (ctr_idx < 0) {
+ sbiret = SBI_ERR_NOT_SUPPORTED;
+ goto out;
+ }
+ }
+
+ 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);
+ }
+
+ 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);
+
+ retdata->out_val = ctr_idx;
+out:
+ retdata->err_val = sbiret;
+
return 0;
}
@@ -192,7 +532,19 @@ void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu)
{
- /* TODO */
+ struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+ struct kvm_pmc *pmc;
+ int i;
+
+ if (!kvpmu)
+ return;
+
+ for_each_set_bit(i, kvpmu->pmc_in_use, RISCV_MAX_COUNTERS) {
+ pmc = &kvpmu->pmc[i];
+ pmc->counter_val = 0;
+ kvm_pmu_release_perf_event(pmc);
+ }
+ bitmap_zero(kvpmu->pmc_in_use, RISCV_MAX_COUNTERS);
}
void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu)
--
2.25.1
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