Re: [PATCH v2 2/9] KVM: s390: Use srcu in kvm_arch_vcpu_unlocked_ioctl()

[Christoph Schlameuss]

On Wed Aug 12, 2026 at 12:44 PM CEST, Claudio Imbrenda wrote:
> kvm_arch_vcpu_unlocked_ioctl() is called without further locks held, but
> kvm_s390_inject_vcpu(), which is called from there, needs either the
> kvm->srcu or the slots lock.
>
> Fix by taking the kvm->srcu in kvm_arch_vcpu_unlocked_ioctl().
>
> Fixes: ba5c1e9b6cee ("KVM: s390: interrupt subsystem, cpu timer, waitpsw")
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>

Reviewed-by: Christoph Schlameuss <schlameuss@xxxxxxxxxxxxx>

> ---
>  arch/s390/kvm/kvm-s390.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 518a69c55e85..b35340642c3e 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -5450,7 +5450,8 @@ long kvm_arch_vcpu_unlocked_ioctl(struct file *filp, unsigned int ioctl,
>  
>  		if (copy_from_user(&s390irq, argp, sizeof(s390irq)))
>  			return -EFAULT;
> -		rc = kvm_s390_inject_vcpu(vcpu, &s390irq);
> +		scoped_guard(srcu, &vcpu->kvm->srcu)
> +			rc = kvm_s390_inject_vcpu(vcpu, &s390irq);
>  		break;
>  	}
>  	case KVM_S390_INTERRUPT: {
> @@ -5463,7 +5464,8 @@ long kvm_arch_vcpu_unlocked_ioctl(struct file *filp, unsigned int ioctl,
>  			return -EFAULT;
>  		if (s390int_to_s390irq(&s390int, &s390irq))
>  			return -EINVAL;
> -		rc = kvm_s390_inject_vcpu(vcpu, &s390irq);
> +		scoped_guard(srcu, &vcpu->kvm->srcu)
> +			rc = kvm_s390_inject_vcpu(vcpu, &s390irq);
>  		break;
>  	}
>  	default: