[PATCH 6.18 180/396] KVM: s390: pci: Reject adapter interrupt forwarding if already enabled

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Farhan Ali <[email protected]>

commit 8fa01be5a6149404adb82c0979a78f6347edd3ef upstream.

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")
Cc: [email protected]
Reviewed-by: Christian Borntraeger <[email protected]>
Reviewed-by: Matthew Rosato <[email protected]>
Signed-off-by: Farhan Ali <[email protected]>
Tested-by: Matthew Rosato <[email protected]>
Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 arch/s390/kvm/pci.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -238,6 +238,10 @@ static int kvm_s390_pci_aif_enable(struc
 	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);