Re: [RFC PATCH v7 12/28] KVM: arm64: Add SPE VCPU device attribute to set the interrupt number

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 03/09/2026 17:06, Alexandru Elisei wrote:
> From: Sudeep Holla <sudeep.holla@arm.com>
> 
> Add KVM_ARM_VCPU_SPE_CTRL(KVM_ARM_VCPU_SPE_IRQ) to allow the user to set
> the interrupt number for the buffer management interrupt.
> 
> [ Alexandru E: Split from "KVM: arm64: Add a new VCPU device control group
>                 for SPE" ]
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> ---

...

> diff --git a/arch/arm64/kvm/spe.c b/arch/arm64/kvm/spe.c
> index fe45ad4c703a..dd5f80318ba4 100644
> --- a/arch/arm64/kvm/spe.c
> +++ b/arch/arm64/kvm/spe.c
> @@ -59,17 +59,99 @@ bool kvm_supports_spe(void)
>   	return !list_empty(&spe_pmus);
>   }
>   

...

>   int kvm_spe_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
>   {
> +	struct kvm_vcpu_spe *vcpu_spe = &vcpu->arch.vcpu_spe;
> +	struct kvm *kvm = vcpu->kvm;
> +
> +	if (!vcpu_has_spe(vcpu))
> +		return -ENODEV;
> +
> +	switch (attr->attr) {
> +	case KVM_ARM_VCPU_SPE_IRQ: {
> +		int __user *uaddr = (int __user *)(long)attr->addr;
> +		int irq;
> +
> +		if (!irqchip_in_kernel(kvm))
> +			return -EINVAL;
> +
> +		if (!vcpu_spe->irq_num)
> +			return -ENXIO;
> +
> +		irq = vcpu_spe->irq_num;
> +		if (put_user(irq, uaddr))
> +			return -EFAULT;
> +
> +		return 0;
> +	}
> +	}
> +
>   	return -ENXIO;
>   }
>   
>   int kvm_spe_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
>   {
> +	if (!vcpu_has_spe(vcpu))
> +		return -ENODEV;
> +
> +	switch(attr->attr) {
> +	case KVM_ARM_VCPU_SPE_IRQ:
> +		return 0;

Should we gate this too on irqchip_in_kernel(vcpu->kvm) ? Otherwise
we would advertise to the userspace that it has the SPE_IRQ, but
would return -EINVAL when we try get_attr if the irqchip is not
in kernel.

Also, do we need to mandate the ordering of the SPE configuration on
VGIC ?

Cheers
Suzuki


> +	}
> +
>   	return -ENXIO;
>   }