[PATCH v7 04/15] s390x: protvirt: Inhibit balloon when switching to protected mode

[Janosch Frank <frankja@linux.ibm.com>]

Ballooning in protected VMs can only be done when the guest shares the
pages it gives to the host. If pages are not shared, the integrity
checks will fail once those pages have been altered and are given back
to the guest.

Hence, until we have a solution for this in the guest kernel, we
inhibit ballooning when switching into protected mode and reverse that
once we move out of it.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 hw/s390x/s390-virtio-ccw.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 4bb38704ff..2557e214a0 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -41,6 +41,7 @@
 #include "hw/qdev-properties.h"
 #include "hw/s390x/tod.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/balloon.h"
 #include "hw/s390x/pv.h"
 #include <linux/kvm.h>
 #include "migration/blocker.h"
@@ -337,6 +338,7 @@ static void s390_machine_unprotect(S390CcwMachineState *ms)
     migrate_del_blocker(pv_mig_blocker);
     error_free(pv_mig_blocker);
     pv_mig_blocker = NULL;
+    qemu_balloon_inhibit(false);
 }
 
 static int s390_machine_protect(S390CcwMachineState *ms)
@@ -345,10 +347,12 @@ static int s390_machine_protect(S390CcwMachineState *ms)
     CPUState *t;
     int rc;
 
+    qemu_balloon_inhibit(true);
     error_setg(&pv_mig_blocker,
                "protected VMs are currently not migrateable.");
     rc = migrate_add_blocker(pv_mig_blocker, &local_err);
     if (local_err) {
+        qemu_balloon_inhibit(false);
         error_report_err(local_err);
         error_free(pv_mig_blocker);
         pv_mig_blocker = NULL;
@@ -358,6 +362,7 @@ static int s390_machine_protect(S390CcwMachineState *ms)
     /* Create SE VM */
     rc = s390_pv_vm_enable();
     if (rc) {
+        qemu_balloon_inhibit(false);
         error_report_err(local_err);
         error_free(pv_mig_blocker);
         pv_mig_blocker = NULL;
-- 
2.20.1