Hi, Bibo,
On Tue, Nov 18, 2025 at 4:07 PM Bibo Mao <[email protected]> wrote:
>
> Function vcpu_is_preempted() is used to check whether vCPU is preempted
> or not. Here add implementation with vcpu_is_preempted() when option
> CONFIG_PARAVIRT is enabled.
>
> Signed-off-by: Bibo Mao <[email protected]>
> ---
> arch/loongarch/include/asm/smp.h | 1 +
> arch/loongarch/include/asm/spinlock.h | 5 +++++
> arch/loongarch/kernel/paravirt.c | 16 ++++++++++++++++
> arch/loongarch/kernel/smp.c | 6 ++++++
> 4 files changed, 28 insertions(+)
>
> diff --git a/arch/loongarch/include/asm/smp.h
> b/arch/loongarch/include/asm/smp.h
> index 3a47f52959a8..5b37f7bf2060 100644
> --- a/arch/loongarch/include/asm/smp.h
> +++ b/arch/loongarch/include/asm/smp.h
> @@ -18,6 +18,7 @@ struct smp_ops {
> void (*init_ipi)(void);
> void (*send_ipi_single)(int cpu, unsigned int action);
> void (*send_ipi_mask)(const struct cpumask *mask, unsigned int
> action);
> + bool (*vcpu_is_preempted)(int cpu);
> };
> extern struct smp_ops mp_ops;
>
> diff --git a/arch/loongarch/include/asm/spinlock.h
> b/arch/loongarch/include/asm/spinlock.h
> index 7cb3476999be..c001cef893aa 100644
> --- a/arch/loongarch/include/asm/spinlock.h
> +++ b/arch/loongarch/include/asm/spinlock.h
> @@ -5,6 +5,11 @@
> #ifndef _ASM_SPINLOCK_H
> #define _ASM_SPINLOCK_H
>
> +#ifdef CONFIG_PARAVIRT
> +#define vcpu_is_preempted vcpu_is_preempted
> +bool vcpu_is_preempted(int cpu);
> +#endif
Maybe paravirt.h is a better place?
> +
> #include <asm/processor.h>
> #include <asm/qspinlock.h>
> #include <asm/qrwlock.h>
> diff --git a/arch/loongarch/kernel/paravirt.c
> b/arch/loongarch/kernel/paravirt.c
> index b1b51f920b23..b99404b6b13f 100644
> --- a/arch/loongarch/kernel/paravirt.c
> +++ b/arch/loongarch/kernel/paravirt.c
> @@ -52,6 +52,13 @@ static u64 paravt_steal_clock(int cpu)
> #ifdef CONFIG_SMP
> static struct smp_ops native_ops;
>
> +static bool pv_vcpu_is_preempted(int cpu)
> +{
> + struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
> +
> + return !!(src->preempted & KVM_VCPU_PREEMPTED);
> +}
> +
> static void pv_send_ipi_single(int cpu, unsigned int action)
> {
> int min, old;
> @@ -308,6 +315,9 @@ int __init pv_time_init(void)
> pr_err("Failed to install cpu hotplug callbacks\n");
> return r;
> }
> +
> + if (kvm_para_has_feature(KVM_FEATURE_PREEMPT_HINT))
> + mp_ops.vcpu_is_preempted = pv_vcpu_is_preempted;
> #endif
>
> static_call_update(pv_steal_clock, paravt_steal_clock);
> @@ -332,3 +342,9 @@ int __init pv_spinlock_init(void)
>
> return 0;
> }
> +
> +bool notrace vcpu_is_preempted(int cpu)
> +{
> + return mp_ops.vcpu_is_preempted(cpu);
> +}
We can simplify the whole patch like this, then we don't need to touch
smp.c, and we can merge Patch-2/3.
+bool notrace vcpu_is_preempted(int cpu)
+{
+ if (!kvm_para_has_feature(KVM_FEATURE_PREEMPT_HINT))
+ return false;
+ else {
+ struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
+ return !!(src->preempted & KVM_VCPU_PREEMPTED);
+ }
+}
Huacai
> +EXPORT_SYMBOL(vcpu_is_preempted);
> diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
> index 46036d98da75..f04192fedf8d 100644
> --- a/arch/loongarch/kernel/smp.c
> +++ b/arch/loongarch/kernel/smp.c
> @@ -307,10 +307,16 @@ static void loongson_init_ipi(void)
> panic("IPI IRQ request failed\n");
> }
>
> +static bool loongson_vcpu_is_preempted(int cpu)
> +{
> + return false;
> +}
> +
> struct smp_ops mp_ops = {
> .init_ipi = loongson_init_ipi,
> .send_ipi_single = loongson_send_ipi_single,
> .send_ipi_mask = loongson_send_ipi_mask,
> + .vcpu_is_preempted = loongson_vcpu_is_preempted,
> };
>
> static void __init fdt_smp_setup(void)
> --
> 2.39.3
>
>
