1 files changed, 243 insertions, 17 deletions

diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 86391a5061dd..04db1f993c47 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -14,6 +14,7 @@
 #include <asm/csr.h>
 #include <asm/kvm_vcpu_sbi.h>
 #include <asm/kvm_vcpu_pmu.h>
+#include <asm/sbi.h>
 #include <linux/bitops.h>
 
 #define kvm_pmu_num_counters(pmu) ((pmu)->num_hw_ctrs + (pmu)->num_fw_ctrs)
@@ -39,7 +40,7 @@ static u64 kvm_pmu_get_sample_period(struct kvm_pmc *pmc)
 	u64 sample_period;
 
 	if (!pmc->counter_val)
-		sample_period = counter_val_mask + 1;
+		sample_period = counter_val_mask;
 	else
 		sample_period = (-pmc->counter_val) & counter_val_mask;
 
@@ -196,6 +197,36 @@ static int pmu_get_pmc_index(struct kvm_pmu *pmu, unsigned long eidx,
 	return kvm_pmu_get_programmable_pmc_index(pmu, eidx, cbase, cmask);
 }
 
+static int pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+			      unsigned long *out_val)
+{
+	struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+	struct kvm_pmc *pmc;
+	int fevent_code;
+
+	if (!IS_ENABLED(CONFIG_32BIT)) {
+		pr_warn("%s: should be invoked for only RV32\n", __func__);
+		return -EINVAL;
+	}
+
+	if (cidx >= kvm_pmu_num_counters(kvpmu) || cidx == 1) {
+		pr_warn("Invalid counter id [%ld]during read\n", cidx);
+		return -EINVAL;
+	}
+
+	pmc = &kvpmu->pmc[cidx];
+
+	if (pmc->cinfo.type != SBI_PMU_CTR_TYPE_FW)
+		return -EINVAL;
+
+	fevent_code = get_event_code(pmc->event_idx);
+	pmc->counter_val = kvpmu->fw_event[fevent_code].value;
+
+	*out_val = pmc->counter_val >> 32;
+
+	return 0;
+}
+
 static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 			unsigned long *out_val)
 {
@@ -204,6 +235,11 @@ static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 	u64 enabled, running;
 	int fevent_code;
 
+	if (cidx >= kvm_pmu_num_counters(kvpmu) || cidx == 1) {
+		pr_warn("Invalid counter id [%ld] during read\n", cidx);
+		return -EINVAL;
+	}
+
 	pmc = &kvpmu->pmc[cidx];
 
 	if (pmc->cinfo.type == SBI_PMU_CTR_TYPE_FW) {
@@ -229,8 +265,50 @@ 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, struct perf_event_attr *attr,
-				     unsigned long flags, unsigned long eidx, unsigned long evtdata)
+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)
 {
 	struct perf_event *event;
 
@@ -247,7 +325,7 @@ static int kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_attr
 	 */
 	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);
@@ -310,6 +388,80 @@ int kvm_riscv_vcpu_pmu_read_hpm(struct kvm_vcpu *vcpu, unsigned int csr_num,
 	return ret;
 }
 
+static void kvm_pmu_clear_snapshot_area(struct kvm_vcpu *vcpu)
+{
+	struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+	int snapshot_area_size = sizeof(struct riscv_pmu_snapshot_data);
+
+	if (kvpmu->sdata) {
+		if (kvpmu->snapshot_addr != INVALID_GPA) {
+			memset(kvpmu->sdata, 0, snapshot_area_size);
+			kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr,
+					     kvpmu->sdata, snapshot_area_size);
+		} else {
+			pr_warn("snapshot address invalid\n");
+		}
+		kfree(kvpmu->sdata);
+		kvpmu->sdata = NULL;
+	}
+	kvpmu->snapshot_addr = INVALID_GPA;
+}
+
+int kvm_riscv_vcpu_pmu_snapshot_set_shmem(struct kvm_vcpu *vcpu, unsigned long saddr_low,
+				      unsigned long saddr_high, unsigned long flags,
+				      struct kvm_vcpu_sbi_return *retdata)
+{
+	struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
+	int snapshot_area_size = sizeof(struct riscv_pmu_snapshot_data);
+	int sbiret = 0;
+	gpa_t saddr;
+	unsigned long hva;
+	bool writable;
+
+	if (!kvpmu || flags) {
+		sbiret = SBI_ERR_INVALID_PARAM;
+		goto out;
+	}
+
+	if (saddr_low == SBI_SHMEM_DISABLE && saddr_high == SBI_SHMEM_DISABLE) {
+		kvm_pmu_clear_snapshot_area(vcpu);
+		return 0;
+	}
+
+	saddr = saddr_low;
+
+	if (saddr_high != 0) {
+		if (IS_ENABLED(CONFIG_32BIT))
+			saddr |= ((gpa_t)saddr_high << 32);
+		else
+			sbiret = SBI_ERR_INVALID_ADDRESS;
+		goto out;
+	}
+
+	hva = kvm_vcpu_gfn_to_hva_prot(vcpu, saddr >> PAGE_SHIFT, &writable);
+	if (kvm_is_error_hva(hva) || !writable) {
+		sbiret = SBI_ERR_INVALID_ADDRESS;
+		goto out;
+	}
+
+	kvpmu->sdata = kzalloc(snapshot_area_size, GFP_ATOMIC);
+	if (!kvpmu->sdata)
+		return -ENOMEM;
+
+	if (kvm_vcpu_write_guest(vcpu, saddr, kvpmu->sdata, snapshot_area_size)) {
+		kfree(kvpmu->sdata);
+		sbiret = SBI_ERR_FAILURE;
+		goto out;
+	}
+
+	kvpmu->snapshot_addr = saddr;
+
+out:
+	retdata->err_val = sbiret;
+
+	return 0;
+}
+
 int kvm_riscv_vcpu_pmu_num_ctrs(struct kvm_vcpu *vcpu,
 				struct kvm_vcpu_sbi_return *retdata)
 {
@@ -343,20 +495,40 @@ int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base,
 	int i, pmc_index, sbiret = 0;
 	struct kvm_pmc *pmc;
 	int fevent_code;
+	bool snap_flag_set = flags & SBI_PMU_START_FLAG_INIT_SNAPSHOT;
 
 	if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
 		sbiret = SBI_ERR_INVALID_PARAM;
 		goto out;
 	}
 
+	if (snap_flag_set) {
+		if (kvpmu->snapshot_addr == INVALID_GPA) {
+			sbiret = SBI_ERR_NO_SHMEM;
+			goto out;
+		}
+		if (kvm_vcpu_read_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata,
+					sizeof(struct riscv_pmu_snapshot_data))) {
+			pr_warn("Unable to read snapshot shared memory while starting counters\n");
+			sbiret = SBI_ERR_FAILURE;
+			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;
+		/* 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)
+		if (flags & SBI_PMU_START_FLAG_SET_INIT_VALUE) {
 			pmc->counter_val = ival;
+		} else if (snap_flag_set) {
+			/* The counter index in the snapshot are relative to the counter base */
+			pmc->counter_val = kvpmu->sdata->ctr_values[i];
+		}
+
 		if (pmc->cinfo.type == SBI_PMU_CTR_TYPE_FW) {
 			fevent_code = get_event_code(pmc->event_idx);
 			if (fevent_code >= SBI_PMU_FW_MAX) {
@@ -400,12 +572,19 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
 	u64 enabled, running;
 	struct kvm_pmc *pmc;
 	int fevent_code;
+	bool snap_flag_set = flags & SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT;
+	bool shmem_needs_update = false;
 
 	if (kvm_pmu_validate_counter_mask(kvpmu, ctr_base, ctr_mask) < 0) {
 		sbiret = SBI_ERR_INVALID_PARAM;
 		goto out;
 	}
 
+	if (snap_flag_set && kvpmu->snapshot_addr == INVALID_GPA) {
+		sbiret = SBI_ERR_NO_SHMEM;
+		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;
@@ -432,21 +611,49 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
 				sbiret = SBI_ERR_ALREADY_STOPPED;
 			}
 
-			if (flags & 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);
+			if (flags & SBI_PMU_STOP_FLAG_RESET)
+				/* Release the counter if this is a reset request */
 				kvm_pmu_release_perf_event(pmc);
-			}
 		} else {
 			sbiret = SBI_ERR_INVALID_PARAM;
 		}
+
+		if (snap_flag_set && !sbiret) {
+			if (pmc->cinfo.type == SBI_PMU_CTR_TYPE_FW)
+				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);
+			/*
+			 * 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;
+		}
+
 		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;
+			}
 		}
 	}
 
+	if (shmem_needs_update)
+		kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, kvpmu->sdata,
+					     sizeof(struct riscv_pmu_snapshot_data));
+
 out:
 	retdata->err_val = sbiret;
 
@@ -458,7 +665,8 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
 				     unsigned long eidx, u64 evtdata,
 				     struct kvm_vcpu_sbi_return *retdata)
 {
-	int ctr_idx, ret, sbiret = 0;
+	int ctr_idx, sbiret = 0;
+	long ret;
 	bool is_fevent;
 	unsigned long event_code;
 	u32 etype = kvm_pmu_get_perf_event_type(eidx);
@@ -517,8 +725,10 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
 			kvpmu->fw_event[event_code].started = true;
 	} else {
 		ret = kvm_pmu_create_perf_event(pmc, &attr, flags, eidx, evtdata);
-		if (ret)
-			return ret;
+		if (ret) {
+			sbiret = SBI_ERR_NOT_SUPPORTED;
+			goto out;
+		}
 	}
 
 	set_bit(ctr_idx, kvpmu->pmc_in_use);
@@ -530,7 +740,19 @@ out:
 	return 0;
 }
 
-int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
+int kvm_riscv_vcpu_pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+				      struct kvm_vcpu_sbi_return *retdata)
+{
+	int ret;
+
+	ret = pmu_fw_ctr_read_hi(vcpu, cidx, &retdata->out_val);
+	if (ret == -EINVAL)
+		retdata->err_val = SBI_ERR_INVALID_PARAM;
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_pmu_fw_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
 				struct kvm_vcpu_sbi_return *retdata)
 {
 	int ret;
@@ -566,6 +788,7 @@ void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
 	kvpmu->num_hw_ctrs = num_hw_ctrs + 1;
 	kvpmu->num_fw_ctrs = SBI_PMU_FW_MAX;
 	memset(&kvpmu->fw_event, 0, SBI_PMU_FW_MAX * sizeof(struct kvm_fw_event));
+	kvpmu->snapshot_addr = INVALID_GPA;
 
 	if (kvpmu->num_hw_ctrs > RISCV_KVM_MAX_HW_CTRS) {
 		pr_warn_once("Limiting the hardware counters to 32 as specified by the ISA");
@@ -585,6 +808,7 @@ 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)
@@ -601,7 +825,7 @@ void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
 			pmc->cinfo.csr = CSR_CYCLE + i;
 		} else {
 			pmc->cinfo.type = SBI_PMU_CTR_TYPE_FW;
-			pmc->cinfo.width = BITS_PER_LONG - 1;
+			pmc->cinfo.width = 63;
 		}
 	}
 
@@ -617,14 +841,16 @@ 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);
 }
 
 void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu)