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

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Message-ID: <20240405-6ef7f32d45deb5edd2d54ecb@orel>
Date: Fri, 5 Apr 2024 14:10:32 +0200
From: Andrew Jones <ajones@...tanamicro.com>
To: Atish Patra <atishp@...osinc.com>
Cc: linux-kernel@...r.kernel.org, Anup Patel <anup@...infault.org>, 
	Ajay Kaher <akaher@...are.com>, Alexandre Ghiti <alexghiti@...osinc.com>, 
	Alexey Makhalov <amakhalov@...are.com>, Conor Dooley <conor.dooley@...rochip.com>, 
	Juergen Gross <jgross@...e.com>, kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	Mark Rutland <mark.rutland@....com>, Palmer Dabbelt <palmer@...belt.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Shuah Khan <shuah@...nel.org>, virtualization@...ts.linux.dev, 
	VMware PV-Drivers Reviewers <pv-drivers@...are.com>, Will Deacon <will@...nel.org>, x86@...nel.org
Subject: Re: [PATCH v5 14/22] RISC-V: KVM: Support 64 bit firmware counters
 on RV32

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@...infault.org>
> Signed-off-by: Atish Patra <atishp@...osinc.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@...tanamicro.com>