Re: [PATCH v4 1/6] KVM: s390: pci: Reject adapter interrupt forwarding if already enabled

[Matthew Rosato]

On 7/22/26 1:06 PM, Farhan Ali wrote:
> The MPCIFC instruction doesn't allow registering adapter interrupts without
> first unregistering. So reject any request to enable interrupt forwarding
> if its already enabled for the zPCI device. This also fixes overwriting and
> thus leaking resources when the ioctl is called multiple times for the same
> device.
> 
> Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
> Signed-off-by: Farhan Ali <alifm@xxxxxxxxxxxxx>

Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>

> ---
>  arch/s390/kvm/pci.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 720bb58cabe2..d2a11cdf6941 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -237,6 +237,10 @@ static int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
>  	if (zdev->gisa == 0)
>  		return -EINVAL;
>  
> +	/* AIF already enabled for the device */
> +	if (zdev->kzdev->fib.fmt0.aibv != 0)
> +		return -EINVAL;
> +
>  	kvm = zdev->kzdev->kvm;
>  	msi_vecs = min_t(unsigned int, fib->fmt0.noi, zdev->max_msi);
>