[PATCH v5 14/22] RISC-V: KVM: Support 64 bit firmware counters on RV32

Atish Patra
2024-04-03T08:05:41Z

The SBI v2.0 introduced a fw_read_hi function to read 64 bit firmware
counters for RV32 based systems.

Add infrastructure to support that.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
arch/riscv/include/asm/kvm_vcpu_pmu.h | 4 ++-
arch/riscv/kvm/vcpu_pmu.c | 44 ++++++++++++++++++++++++++-
arch/riscv/kvm/vcpu_sbi_pmu.c | 6 ++++
3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
index 257f17641e00..55861b5d3382 100644
--- a/arch/riscv/include/asm/kvm_vcpu_pmu.h
+++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h
@@ -20,7 +20,7 @@ static_assert(RISCV_KVM_MAX_COUNTERS <= 64);

struct kvm_fw_event {
/* Current value of the event */
- unsigned long value;
+ u64 value;

/* Event monitoring status */
bool started;
@@ -91,6 +91,8 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
struct kvm_vcpu_sbi_return *retdata);
int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
struct kvm_vcpu_sbi_return *retdata);
+int kvm_riscv_vcpu_pmu_fw_ctr_read_hi(struct kvm_vcpu *vcpu, unsigned long cidx,
+ struct kvm_vcpu_sbi_return *retdata);
void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu);
int kvm_riscv_vcpu_pmu_snapshot_set_shmem(struct kvm_vcpu *vcpu, unsigned long saddr_low,
unsigned long saddr_high, unsigned long flags,
diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 9fedf9dc498b..ff326152eeff 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -197,6 +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)
{
@@ -705,6 +735,18 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
return 0;
}

+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_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
struct kvm_vcpu_sbi_return *retdata)
{
@@ -778,7 +820,7 @@ 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;
}
}

diff --git a/arch/riscv/kvm/vcpu_sbi_pmu.c b/arch/riscv/kvm/vcpu_sbi_pmu.c
index d3e7625fb2d2..cf111de51bdb 100644
--- a/arch/riscv/kvm/vcpu_sbi_pmu.c
+++ b/arch/riscv/kvm/vcpu_sbi_pmu.c
@@ -64,6 +64,12 @@ static int kvm_sbi_ext_pmu_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
case SBI_EXT_PMU_COUNTER_FW_READ:
ret = kvm_riscv_vcpu_pmu_ctr_read(vcpu, cp->a0, retdata);
break;
+ case SBI_EXT_PMU_COUNTER_FW_READ_HI:
+ if (IS_ENABLED(CONFIG_32BIT))
+ ret = kvm_riscv_vcpu_pmu_fw_ctr_read_hi(vcpu, cp->a0, retdata);
+ else
+ retdata->out_val = 0;
+ break;
case SBI_EXT_PMU_SNAPSHOT_SET_SHMEM:
ret = kvm_riscv_vcpu_pmu_snapshot_set_shmem(vcpu, cp->a0, cp->a1, cp->a2, retdata);
break;
--
2.34.1