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Message-ID: <20240302-7679c8f67984ccae734926ba@orel>
Date: Sat, 2 Mar 2024 11:52:02 +0100
From: Andrew Jones <ajones@...tanamicro.com>
To: Atish Patra <atishp@...osinc.com>
Cc: linux-kernel@...r.kernel.org, Anup Patel <anup@...infault.org>,
Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alexghiti@...osinc.com>,
Atish Patra <atishp@...shpatra.org>, Conor Dooley <conor.dooley@...rochip.com>,
Guo Ren <guoren@...nel.org>, Icenowy Zheng <uwu@...nowy.me>, 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>, Will Deacon <will@...nel.org>
Subject: Re: [PATCH v4 10/15] RISC-V: KVM: Support 64 bit firmware counters
on RV32
On Wed, Feb 28, 2024 at 05:01:25PM -0800, 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 | 37 ++++++++++++++++++++++++++-
> arch/riscv/kvm/vcpu_sbi_pmu.c | 6 +++++
> 3 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> index 8cb21a4f862c..e0ad27dea46c 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_setup_snapshot(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 a02f7b981005..469bb430cf97 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -196,6 +196,29 @@ 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))
Let's remove the CONFIG_32BIT check in kvm_sbi_ext_pmu_handler() and then
set *out_val to zero here and return success. Either that, or we should
WARN or something here since it's a KVM bug to get here with
!CONFIG_32BIT.
> + return -EINVAL;
> +
> + pmc = &kvpmu->pmc[cidx];
Uh oh! We're missing range validation of cidx! And I see we're missing it
in pmu_ctr_read() too. We need the same check we have in
kvm_riscv_vcpu_pmu_ctr_info(). I think the other SBI functions are OK,
but it's worth a triple check.
> +
> + 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)
> {
> @@ -702,6 +725,18 @@ 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;
I see this follows the pattern we have with kvm_riscv_vcpu_pmu_ctr_read
and pmu_ctr_read, but I wonder if we really need the
kvm_riscv_vcpu_pmu_ctr_read() and kvm_riscv_vcpu_pmu_fw_ctr_read_hi()
wrapper functions?
> +}
> +
> int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
> struct kvm_vcpu_sbi_return *retdata)
> {
> @@ -775,7 +810,7 @@ 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 9f61136e4bb1..58a0e5587e2a 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_setup_snapshot(vcpu, cp->a0, cp->a1, cp->a2, retdata);
> break;
> --
> 2.34.1
>
Thanks,
drew
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