[PATCH] KVM: riscv: Avoid redundant interrupt check for pending timers

[PATCH] KVM: riscv: Avoid redundant interrupt check for pending timers

[Jinyu Tang]

kvm_vcpu_check_block() calls kvm_arch_vcpu_runnable() before
checking whether a timer is pending. On RISC-V, kvm_arch_vcpu_runnable()
already checks all pending guest interrupts through
kvm_riscv_vcpu_has_interrupts(vcpu, -1UL), including IRQ_VS_TIMER.

Drop the repeated IRQ_VS_TIMER pending-interrupt check from
kvm_riscv_vcpu_timer_pending() and keep the helper focused on the timer
deadline state. If the timer becomes pending after the runnable check,
the timer path still injects IRQ_VS_TIMER and kicks the vCPU through the
normal wakeup path.

Signed-off-by: Jinyu Tang <jinyu.tang@linux.dev>
---
 arch/riscv/kvm/vcpu_timer.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c
index ae53133c7ab0..0e01bd793772 100644
--- a/arch/riscv/kvm/vcpu_timer.c
+++ b/arch/riscv/kvm/vcpu_timer.c
@@ -132,11 +132,7 @@ bool kvm_riscv_vcpu_timer_pending(struct kvm_vcpu *vcpu)
 	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
 	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
 
-	if (!kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t) ||
-	    kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER))
-		return true;
-	else
-		return false;
+	return !kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t);
 }
 
 static void kvm_riscv_vcpu_timer_blocking(struct kvm_vcpu *vcpu)
-- 
2.43.0


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Re: [PATCH] KVM: riscv: Avoid redundant interrupt check for pending timers

[Nutty.Liu]

On 8/14/2026 8:35 PM, Jinyu Tang wrote:
> kvm_vcpu_check_block() calls kvm_arch_vcpu_runnable() before
> checking whether a timer is pending. On RISC-V, kvm_arch_vcpu_runnable()
> already checks all pending guest interrupts through
> kvm_riscv_vcpu_has_interrupts(vcpu, -1UL), including IRQ_VS_TIMER.
>
> Drop the repeated IRQ_VS_TIMER pending-interrupt check from
> kvm_riscv_vcpu_timer_pending() and keep the helper focused on the timer
> deadline state. If the timer becomes pending after the runnable check,
> the timer path still injects IRQ_VS_TIMER and kicks the vCPU through the
> normal wakeup path.
>
> Signed-off-by: Jinyu Tang <jinyu.tang@linux.dev>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>

Thanks,
Nutty
> ---
>   arch/riscv/kvm/vcpu_timer.c | 6 +-----
>   1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c
> index ae53133c7ab0..0e01bd793772 100644
> --- a/arch/riscv/kvm/vcpu_timer.c
> +++ b/arch/riscv/kvm/vcpu_timer.c
> @@ -132,11 +132,7 @@ bool kvm_riscv_vcpu_timer_pending(struct kvm_vcpu *vcpu)
>   	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
>   	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
>   
> -	if (!kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t) ||
> -	    kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER))
> -		return true;
> -	else
> -		return false;
> +	return !kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t);
>   }
>   
>   static void kvm_riscv_vcpu_timer_blocking(struct kvm_vcpu *vcpu)

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Re: [PATCH] KVM: riscv: Avoid redundant interrupt check for pending timers

[Anup Patel]

On Fri, Aug 14, 2026 at 6:06 PM Jinyu Tang <jinyu.tang@linux.dev> wrote:
>
> kvm_vcpu_check_block() calls kvm_arch_vcpu_runnable() before
> checking whether a timer is pending. On RISC-V, kvm_arch_vcpu_runnable()
> already checks all pending guest interrupts through
> kvm_riscv_vcpu_has_interrupts(vcpu, -1UL), including IRQ_VS_TIMER.
>
> Drop the repeated IRQ_VS_TIMER pending-interrupt check from
> kvm_riscv_vcpu_timer_pending() and keep the helper focused on the timer
> deadline state. If the timer becomes pending after the runnable check,
> the timer path still injects IRQ_VS_TIMER and kicks the vCPU through the
> normal wakeup path.
>
> Signed-off-by: Jinyu Tang <jinyu.tang@linux.dev>

LGTM.

Reviewed-by: Anup Patel <anup@brainfault.org>

Queued this patch for Linux-7.4

Thanks,
Anup


> ---
>  arch/riscv/kvm/vcpu_timer.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c
> index ae53133c7ab0..0e01bd793772 100644
> --- a/arch/riscv/kvm/vcpu_timer.c
> +++ b/arch/riscv/kvm/vcpu_timer.c
> @@ -132,11 +132,7 @@ bool kvm_riscv_vcpu_timer_pending(struct kvm_vcpu *vcpu)
>         struct kvm_vcpu_timer *t = &vcpu->arch.timer;
>         struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
>
> -       if (!kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t) ||
> -           kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER))
> -               return true;
> -       else
> -               return false;
> +       return !kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t);
>  }
>
>  static void kvm_riscv_vcpu_timer_blocking(struct kvm_vcpu *vcpu)
> --
> 2.43.0
>

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