Re: [PATCH v2] KVM: s390: pci: Fix GISC refcount leak on AIF enable failure

[Matthew Rosato]

On 6/24/26 2:19 AM, Haoxiang Li wrote:
> kvm_s390_gisc_register() registers the guest ISC before pinning
> the guest interrupt forwarding pages and allocating the AISB bit.
> If any of the later setup steps fails, the function unwinds the
> pinned pages and other local state, but does not unregister the
> GISC reference. Add the missing kvm_s390_gisc_unregister() to the
> error unwind path.
> 
> Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Haoxiang Li <haoxiang_li2024@xxxxxxx>

Thanks, code looks good:

Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>

Forced the codepath in question on s390 w/ passthrough devices, so feel
free to also add:

Tested-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>

> ---
> Changes in v2:
>  - Move unregister call after "out" label. Thanks, Matt!
> ---
>  arch/s390/kvm/pci.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 5b075c38998e..686113be0530 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -328,6 +328,7 @@ static int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
>  unpin1:
>  	unpin_user_page(aibv_page);
>  out:
> +	kvm_s390_gisc_unregister(kvm, fib->fmt0.isc);
>  	return rc;
>  }
>