s390x/pci: avoid double enable/disable of aif

Use a flag to keep track of whether AIF is currently enabled.  This can be
used to avoid enabling/disabling AIF multiple times as well as to determine
whether or not it should be disabled during reset processing.

Fixes: d0bc7091 ("s390x/pci: enable adapter event notification for interpreted devices")
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: <20240118185151.265329-2-mjrosato@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 07b2c8e034d80ff92e202405c494d2ff80fcf848)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/s390x/s390-pci-kvm.c

@@ -27,6 +27,7 @@ bool s390_pci_kvm_interp_allowed(void)
 
 int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, ZpciFib *fib, bool assist)
 {
+    int rc;
     struct kvm_s390_zpci_op args = {
         .fh = pbdev->fh,
         .op = KVM_S390_ZPCIOP_REG_AEN,
@@ -38,15 +39,35 @@ int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, ZpciFib *fib, bool assist)
         .u.reg_aen.flags = (assist) ? 0 : KVM_S390_ZPCIOP_REGAEN_HOST
     };
 
-    return kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
+    if (pbdev->aif) {
+        return -EINVAL;
+    }
+
+    rc = kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
+    if (rc == 0) {
+        pbdev->aif = true;
+    }
+
+    return rc;
 }
 
 int s390_pci_kvm_aif_disable(S390PCIBusDevice *pbdev)
 {
+    int rc;
+
     struct kvm_s390_zpci_op args = {
         .fh = pbdev->fh,
         .op = KVM_S390_ZPCIOP_DEREG_AEN
     };
 
-    return kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
+    if (!pbdev->aif) {
+        return -EINVAL;
+    }
+
+    rc = kvm_vm_ioctl(kvm_state, KVM_S390_ZPCI_OP, &args);
+    if (rc == 0) {
+        pbdev->aif = false;
+    }
+
+    return rc;
 }

include/hw/s390x/s390-pci-bus.h

@@ -361,6 +361,7 @@ struct S390PCIBusDevice {
     bool unplug_requested;
     bool interp;
     bool forwarding_assist;
+    bool aif;
     QTAILQ_ENTRY(S390PCIBusDevice) link;
 };