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

Andrew Jones
2024-04-05T12:10:36Z

On Wed, Apr 03, 2024 at 01:04:43AM -0700, Atish Patra wrote:
> 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
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>