Re: [PATCH v5 08/22] RISC-V: KVM: Fix the initial sample period value

Andrew Jones
2024-04-04T11:57:39Z

On Wed, Apr 03, 2024 at 01:04:37AM -0700, Atish Patra wrote:
> The initial sample period value when counter value is not assigned
> should be set to maximum value supported by the counter width.
> Otherwise, it may result in spurious interrupts.
>
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> ---
> arch/riscv/kvm/vcpu_pmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> index 86391a5061dd..cee1b9ca4ec4 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -39,7 +39,7 @@ 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;
>
> --
> 2.34.1
>

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