Message-Id: <20230127182558.2416400-14-atishp@rivosinc.com>
Date:   Fri, 27 Jan 2023 10:25:57 -0800
From:   Atish Patra <atishp@...osinc.com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atishp@...osinc.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        Guo Ren <guoren@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
        kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org,
        linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Sergey Matyukevich <sergey.matyukevich@...tacore.com>,
        Will Deacon <will@...nel.org>
Subject: [PATCH v3 13/14] RISC-V: KVM: Support firmware events

SBI PMU extension defines a set of firmware events which can provide
useful information to guests about number of SBI calls. As hypervisor
implements the SBI PMU extension, these firmware events corresponds
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@...osinc.com>
---
 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

Powered by blists - more mailing lists