vfio: Add migration region initialization and finalize function

Whether the VFIO device supports migration or not is decided based of
migration region query. If migration region query is successful and migration
region initialization is successful then migration is supported else
migration is blocked.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/vfio/meson.build

@@ -2,6 +2,7 @@ vfio_ss = ss.source_set()
 vfio_ss.add(files(
   'common.c',
   'spapr.c',
+  'migration.c',
 ))
 vfio_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(
   'display.c',

hw/vfio/migration.c

@@ -0,0 +1,122 @@
+/*
+ * Migration support for VFIO devices
+ *
+ * Copyright NVIDIA, Inc. 2020
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include <linux/vfio.h>
+
+#include "hw/vfio/vfio-common.h"
+#include "cpu.h"
+#include "migration/migration.h"
+#include "migration/qemu-file.h"
+#include "migration/register.h"
+#include "migration/blocker.h"
+#include "migration/misc.h"
+#include "qapi/error.h"
+#include "exec/ramlist.h"
+#include "exec/ram_addr.h"
+#include "pci.h"
+#include "trace.h"
+
+static void vfio_migration_exit(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+
+    vfio_region_exit(&migration->region);
+    vfio_region_finalize(&migration->region);
+    g_free(vbasedev->migration);
+    vbasedev->migration = NULL;
+}
+
+static int vfio_migration_init(VFIODevice *vbasedev,
+                               struct vfio_region_info *info)
+{
+    int ret;
+    Object *obj;
+
+    if (!vbasedev->ops->vfio_get_object) {
+        return -EINVAL;
+    }
+
+    obj = vbasedev->ops->vfio_get_object(vbasedev);
+    if (!obj) {
+        return -EINVAL;
+    }
+
+    vbasedev->migration = g_new0(VFIOMigration, 1);
+
+    ret = vfio_region_setup(obj, vbasedev, &vbasedev->migration->region,
+                            info->index, "migration");
+    if (ret) {
+        error_report("%s: Failed to setup VFIO migration region %d: %s",
+                     vbasedev->name, info->index, strerror(-ret));
+        goto err;
+    }
+
+    if (!vbasedev->migration->region.size) {
+        error_report("%s: Invalid zero-sized VFIO migration region %d",
+                     vbasedev->name, info->index);
+        ret = -EINVAL;
+        goto err;
+    }
+    return 0;
+
+err:
+    vfio_migration_exit(vbasedev);
+    return ret;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int vfio_migration_probe(VFIODevice *vbasedev, Error **errp)
+{
+    struct vfio_region_info *info = NULL;
+    Error *local_err = NULL;
+    int ret;
+
+    ret = vfio_get_dev_region_info(vbasedev, VFIO_REGION_TYPE_MIGRATION,
+                                   VFIO_REGION_SUBTYPE_MIGRATION, &info);
+    if (ret) {
+        goto add_blocker;
+    }
+
+    ret = vfio_migration_init(vbasedev, info);
+    if (ret) {
+        goto add_blocker;
+    }
+
+    g_free(info);
+    trace_vfio_migration_probe(vbasedev->name, info->index);
+    return 0;
+
+add_blocker:
+    error_setg(&vbasedev->migration_blocker,
+               "VFIO device doesn't support migration");
+    g_free(info);
+
+    ret = migrate_add_blocker(vbasedev->migration_blocker, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        error_free(vbasedev->migration_blocker);
+        vbasedev->migration_blocker = NULL;
+    }
+    return ret;
+}
+
+void vfio_migration_finalize(VFIODevice *vbasedev)
+{
+    if (vbasedev->migration) {
+        vfio_migration_exit(vbasedev);
+    }
+
+    if (vbasedev->migration_blocker) {
+        migrate_del_blocker(vbasedev->migration_blocker);
+        error_free(vbasedev->migration_blocker);
+        vbasedev->migration_blocker = NULL;
+    }
+}

hw/vfio/trace-events

@@ -145,3 +145,6 @@ vfio_display_edid_link_up(void) ""
 vfio_display_edid_link_down(void) ""
 vfio_display_edid_update(uint32_t prefx, uint32_t prefy) "%ux%u"
 vfio_display_edid_write_error(void) ""
+
+# migration.c
+vfio_migration_probe(const char *name, uint32_t index) " (%s) Region %d"

include/hw/vfio/vfio-common.h

@@ -57,6 +57,10 @@ typedef struct VFIORegion {
     uint8_t nr; /* cache the region number for debug */
 } VFIORegion;
 
+typedef struct VFIOMigration {
+    VFIORegion region;
+} VFIOMigration;
+
 typedef struct VFIOAddressSpace {
     AddressSpace *as;
     QLIST_HEAD(, VFIOContainer) containers;
@@ -113,6 +117,8 @@ typedef struct VFIODevice {
     unsigned int num_irqs;
     unsigned int num_regions;
     unsigned int flags;
+    VFIOMigration *migration;
+    Error *migration_blocker;
 } VFIODevice;
 
 struct VFIODeviceOps {
@@ -204,4 +210,7 @@ int vfio_spapr_create_window(VFIOContainer *container,
 int vfio_spapr_remove_window(VFIOContainer *container,
                              hwaddr offset_within_address_space);
 
+int vfio_migration_probe(VFIODevice *vbasedev, Error **errp);
+void vfio_migration_finalize(VFIODevice *vbasedev);
+
 #endif /* HW_VFIO_VFIO_COMMON_H */