[v2] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS

[PATCH v2] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS

Posted by Qiang Ma 1 month, 2 weeks ago

It doesn't make sense to return the recommended maximum number of
vCPUs which exceeds the maximum possible number of vCPUs.

Other architectures have already done this, such as Commit
57a2e13ebdda ("KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS")

Signed-off-by: Qiang Ma <maqianga@uniontech.com>
---
 arch/loongarch/kvm/vm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
index 8cc5ee1c53ef..1317c718f896 100644
--- a/arch/loongarch/kvm/vm.c
+++ b/arch/loongarch/kvm/vm.c
@@ -125,7 +125,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = 1;
 		break;
 	case KVM_CAP_NR_VCPUS:
-		r = num_online_cpus();
+		r = min_t(unsigned int, num_online_cpus(), KVM_MAX_VCPUS);
 		break;
 	case KVM_CAP_MAX_VCPUS:
 		r = KVM_MAX_VCPUS;
-- 
2.20.1

Re: [PATCH v2] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS

Posted by Bibo Mao 1 month, 2 weeks ago

On 2026/4/28 下午8:18, Qiang Ma wrote:
> It doesn't make sense to return the recommended maximum number of
> vCPUs which exceeds the maximum possible number of vCPUs.
> 
> Other architectures have already done this, such as Commit
> 57a2e13ebdda ("KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS")
> 
> Signed-off-by: Qiang Ma <maqianga@uniontech.com>
> ---
>   arch/loongarch/kvm/vm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
> index 8cc5ee1c53ef..1317c718f896 100644
> --- a/arch/loongarch/kvm/vm.c
> +++ b/arch/loongarch/kvm/vm.c
> @@ -125,7 +125,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>   		r = 1;
>   		break;
>   	case KVM_CAP_NR_VCPUS:
> -		r = num_online_cpus();
> +		r = min_t(unsigned int, num_online_cpus(), KVM_MAX_VCPUS);
>   		break;
>   	case KVM_CAP_MAX_VCPUS:
>   		r = KVM_MAX_VCPUS;
> 
Reviewed-by: Bibo Mao <maobibo@loongson.cn>

Re: [PATCH v2] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS

Posted by Huacai Chen 1 month, 2 weeks ago

On Tue, Apr 28, 2026 at 8:59 PM Bibo Mao <maobibo@loongson.cn> wrote:
>
> On 2026/4/28 下午8:18, Qiang Ma wrote:
> > It doesn't make sense to return the recommended maximum number of
> > vCPUs which exceeds the maximum possible number of vCPUs.
> >
> > Other architectures have already done this, such as Commit
> > 57a2e13ebdda ("KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS")
> >
> > Signed-off-by: Qiang Ma <maqianga@uniontech.com>
> > ---
> >   arch/loongarch/kvm/vm.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
> > index 8cc5ee1c53ef..1317c718f896 100644
> > --- a/arch/loongarch/kvm/vm.c
> > +++ b/arch/loongarch/kvm/vm.c
> > @@ -125,7 +125,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> >               r = 1;
> >               break;
> >       case KVM_CAP_NR_VCPUS:
> > -             r = num_online_cpus();
> > +             r = min_t(unsigned int, num_online_cpus(), KVM_MAX_VCPUS);
> >               break;
> >       case KVM_CAP_MAX_VCPUS:
> >               r = KVM_MAX_VCPUS;
> >
> Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Applied, thanks.

Huacai
>