vfio/migration: Emit VFIO migration QAPI event

Emit VFIO migration QAPI event when a VFIO device changes its migration
state. This can be used by management applications to get updates on the
current state of the VFIO device for their own purposes.

A new per VFIO device capability, "migration-events", is added so events
can be enabled only for the required devices. It is disabled by default.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/migration.c

@@ -24,6 +24,7 @@
 #include "migration/register.h"
 #include "migration/blocker.h"
 #include "qapi/error.h"
+#include "qapi/qapi-events-vfio.h"
 #include "exec/ramlist.h"
 #include "exec/ram_addr.h"
 #include "pci.h"
@@ -80,6 +81,58 @@ static const char *mig_state_to_str(enum vfio_device_mig_state state)
     }
 }
 
+static VfioMigrationState
+mig_state_to_qapi_state(enum vfio_device_mig_state state)
+{
+    switch (state) {
+    case VFIO_DEVICE_STATE_STOP:
+        return QAPI_VFIO_MIGRATION_STATE_STOP;
+    case VFIO_DEVICE_STATE_RUNNING:
+        return QAPI_VFIO_MIGRATION_STATE_RUNNING;
+    case VFIO_DEVICE_STATE_STOP_COPY:
+        return QAPI_VFIO_MIGRATION_STATE_STOP_COPY;
+    case VFIO_DEVICE_STATE_RESUMING:
+        return QAPI_VFIO_MIGRATION_STATE_RESUMING;
+    case VFIO_DEVICE_STATE_RUNNING_P2P:
+        return QAPI_VFIO_MIGRATION_STATE_RUNNING_P2P;
+    case VFIO_DEVICE_STATE_PRE_COPY:
+        return QAPI_VFIO_MIGRATION_STATE_PRE_COPY;
+    case VFIO_DEVICE_STATE_PRE_COPY_P2P:
+        return QAPI_VFIO_MIGRATION_STATE_PRE_COPY_P2P;
+    default:
+        g_assert_not_reached();
+    }
+}
+
+static void vfio_migration_send_event(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    DeviceState *dev = vbasedev->dev;
+    g_autofree char *qom_path = NULL;
+    Object *obj;
+
+    if (!vbasedev->migration_events) {
+        return;
+    }
+
+    g_assert(vbasedev->ops->vfio_get_object);
+    obj = vbasedev->ops->vfio_get_object(vbasedev);
+    g_assert(obj);
+    qom_path = object_get_canonical_path(obj);
+
+    qapi_event_send_vfio_migration(
+        dev->id, qom_path, mig_state_to_qapi_state(migration->device_state));
+}
+
+static void vfio_migration_set_device_state(VFIODevice *vbasedev,
+                                            enum vfio_device_mig_state state)
+{
+    VFIOMigration *migration = vbasedev->migration;
+
+    migration->device_state = state;
+    vfio_migration_send_event(vbasedev);
+}
+
 static int vfio_migration_set_state(VFIODevice *vbasedev,
                                     enum vfio_device_mig_state new_state,
                                     enum vfio_device_mig_state recover_state,
@@ -131,12 +184,12 @@ static int vfio_migration_set_state(VFIODevice *vbasedev,
             goto reset_device;
         }
 
-        migration->device_state = recover_state;
+        vfio_migration_set_device_state(vbasedev, recover_state);
 
         return ret;
     }
 
-    migration->device_state = new_state;
+    vfio_migration_set_device_state(vbasedev, new_state);
     if (mig_state->data_fd != -1) {
         if (migration->data_fd != -1) {
             /*
@@ -162,7 +215,7 @@ reset_device:
                  strerror(errno));
     }
 
-    migration->device_state = VFIO_DEVICE_STATE_RUNNING;
+    vfio_migration_set_device_state(vbasedev, VFIO_DEVICE_STATE_RUNNING);
 
     return ret;
 }

hw/vfio/pci.c

@@ -3388,6 +3388,8 @@ static Property vfio_pci_dev_properties[] = {
                     VFIO_FEATURE_ENABLE_IGD_OPREGION_BIT, false),
     DEFINE_PROP_ON_OFF_AUTO("enable-migration", VFIOPCIDevice,
                             vbasedev.enable_migration, ON_OFF_AUTO_AUTO),
+    DEFINE_PROP_BOOL("migration-events", VFIOPCIDevice,
+                     vbasedev.migration_events, false),
     DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false),
     DEFINE_PROP_BOOL("x-balloon-allowed", VFIOPCIDevice,
                      vbasedev.ram_block_discard_allowed, false),

include/hw/vfio/vfio-common.h

@@ -115,6 +115,7 @@ typedef struct VFIODevice {
     bool no_mmap;
     bool ram_block_discard_allowed;
     OnOffAuto enable_migration;
+    bool migration_events;
     VFIODeviceOps *ops;
     unsigned int num_irqs;
     unsigned int num_regions;