s390x/pci: refresh fh before disabling aif

Typically we refresh the host fh during CLP enable, however it's possible
that the device goes through multiple reset events before the guest
performs another CLP enable.  Let's handle this for now by refreshing the
host handle from vfio before disabling aif.

Fixes: 03451953c7 ("s390x/pci: reset ISM passthrough devices on shutdown and system reset")
Reported-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Message-ID: <20240118185151.265329-3-mjrosato@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/s390x/s390-pci-kvm.c

@@ -18,6 +18,7 @@
 #include "hw/s390x/s390-pci-bus.h"
 #include "hw/s390x/s390-pci-kvm.h"
 #include "hw/s390x/s390-pci-inst.h"
+#include "hw/s390x/s390-pci-vfio.h"
 #include "cpu_models.h"
 
 bool s390_pci_kvm_interp_allowed(void)
@@ -64,6 +65,14 @@ int s390_pci_kvm_aif_disable(S390PCIBusDevice *pbdev)
         return -EINVAL;
     }
 
+    /*
+     * The device may have already been reset but we still want to relinquish
+     * the guest ISC, so always be sure to use an up-to-date host fh.
+     */
+    if (!s390_pci_get_host_fh(pbdev, &args.fh)) {
+        return -EPERM;
+    }
+
     rc = kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
     if (rc == 0) {
         pbdev->aif = false;