[PATCH V9 46/46] vfio: allow cpr-reboot migration if suspended

[Steve Sistare]

The cpr-reboot mode supports vfio devices if the caller first suspends the
guest, such as by issuing guest-suspend-ram to the qemu guest agent.  The
guest drivers' suspend methods flush outstanding requests and re-initialize
the devices, and thus there is no device state to save and restore.

Relax the vfio blocker, and add a notifier that verifies the guest is
suspended.  Skip dirty page tracking to avoid ioctl errors.

Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
 hw/vfio/common.c              |  8 ++++++--
 hw/vfio/cpr.c                 | 21 +++++++++++++++++++++
 hw/vfio/migration.c           |  3 ++-
 include/hw/vfio/vfio-common.h |  1 +
 4 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index de821e1..5b54cbe 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1355,14 +1355,18 @@ static void 
vfio_listener_log_global_start(MemoryListener *listener)
 {
     VFIOContainer *container = container_of(listener, VFIOContainer, listener);
 
-    vfio_set_dirty_page_tracking(container, true);
+    if (!runstate_check(RUN_STATE_SUSPENDED)) {
+        vfio_set_dirty_page_tracking(container, true);
+    }
 }
 
 static void vfio_listener_log_global_stop(MemoryListener *listener)
 {
     VFIOContainer *container = container_of(listener, VFIOContainer, listener);
 
-    vfio_set_dirty_page_tracking(container, false);
+    if (!runstate_check(RUN_STATE_SUSPENDED)) {
+        vfio_set_dirty_page_tracking(container, false);
+    }
 }
 
 static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
diff --git a/hw/vfio/cpr.c b/hw/vfio/cpr.c
index 1f682cb..ef8827c 100644
--- a/hw/vfio/cpr.c
+++ b/hw/vfio/cpr.c
@@ -10,6 +10,7 @@
 #include <linux/vfio.h>
 #include "hw/vfio/vfio-common.h"
 #include "sysemu/kvm.h"
+#include "sysemu/runstate.h"
 #include "qapi/error.h"
 #include "migration/blocker.h"
 #include "migration/migration.h"
@@ -132,8 +133,26 @@ static void vfio_cpr_fail_notifier(Notifier *notifier, 
void *data)
     }
 }
 
+static void vfio_cpr_reboot_notifier(Notifier *notifier, void *data)
+{
+    MigrationState *s = data;
+
+    if (migrate_mode_of(s) == MIG_MODE_CPR_REBOOT &&
+        !migration_has_failed(s) &&
+        !runstate_check(RUN_STATE_SUSPENDED)) {
+
+        Error *err = NULL;
+        error_setg(&err, "VFIO device only supports cpr-reboot for "
+                         "runstate suspended");
+        migration_notifier_set_error(s, err);
+    }
+}
+
 int vfio_cpr_register_container(VFIOContainer *container, Error **errp)
 {
+    migration_add_notifier(&container->cpr_reboot_notifier,
+                           vfio_cpr_reboot_notifier);
+
     container->cpr_blocker = NULL;
     if (!vfio_is_cpr_capable(container, &container->cpr_blocker)) {
         return migrate_add_blockers(&container->cpr_blocker, errp,
@@ -148,6 +167,8 @@ int vfio_cpr_register_container(VFIOContainer *container, 
Error **errp)
 
 void vfio_cpr_unregister_container(VFIOContainer *container)
 {
+    migration_remove_notifier(&container->cpr_reboot_notifier);
+
     migrate_del_blocker(&container->cpr_blocker);
 
     vmstate_unregister(NULL, &vfio_container_vmstate, container);
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 6b0d401..3919941 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -890,7 +890,8 @@ add_blocker:
                "VFIO device doesn't support migration");
     g_free(info);
 
-    return migrate_add_blocker(&vbasedev->migration_blocker, errp);
+    return migrate_add_blockers(&vbasedev->migration_blocker, errp,
+                                MIG_MODE_NORMAL, -1);
 }
 
 void vfio_migration_finalize(VFIODevice *vbasedev)
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index b682645..243376b 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -83,6 +83,7 @@ typedef struct VFIOContainer {
     MemoryListener prereg_listener;
     Notifier cpr_notifier;
     Error *cpr_blocker;
+    Notifier cpr_reboot_notifier;
     unsigned iommu_type;
     Error *error;
     bool initialized;
-- 
1.8.3.1