[Qemu-devel] [PATCH v4 07/13] vfio: Register SaveVMHandlers for VFIO device

[Kirti Wankhede <kwankhede@nvidia.com>]

Define flags to be used as delimeter in migration file stream.
Added .save_setup and .save_cleanup functions. Mapped & unmapped migration
region from these functions at source during saving or pre-copy phase.
Set VFIO device state depending on VM's state. During live migration, VM is
running when .save_setup is called, _SAVING | _RUNNING state is set for VFIO
device. During save-restore, VM is paused, _SAVING state is set for VFIO device.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 hw/vfio/migration.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 75 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 7f9858e6c995..fe0887c27664 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -22,6 +22,17 @@
 #include "exec/ram_addr.h"
 #include "pci.h"
 
+/*
+ * Flags used as delimiter:
+ * 0xffffffff => MSB 32-bit all 1s
+ * 0xef10     => emulated (virtual) function IO
+ * 0x0000     => 16-bits reserved for flags
+ */
+#define VFIO_MIG_FLAG_END_OF_STATE      (0xffffffffef100001ULL)
+#define VFIO_MIG_FLAG_DEV_CONFIG_STATE  (0xffffffffef100002ULL)
+#define VFIO_MIG_FLAG_DEV_SETUP_STATE   (0xffffffffef100003ULL)
+#define VFIO_MIG_FLAG_DEV_DATA_STATE    (0xffffffffef100004ULL)
+
 static void vfio_migration_region_exit(VFIODevice *vbasedev)
 {
     VFIOMigration *migration = vbasedev->migration;
@@ -96,6 +107,69 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t state)
     return 0;
 }
 
+/* ---------------------------------------------------------------------- */
+
+static int vfio_save_setup(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    int ret;
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_SETUP_STATE);
+
+    if (migration->region.buffer.mmaps) {
+        qemu_mutex_lock_iothread();
+        ret = vfio_region_mmap(&migration->region.buffer);
+        qemu_mutex_unlock_iothread();
+        if (ret) {
+            error_report("Failed to mmap VFIO migration region %d: %s",
+                         migration->region.index, strerror(-ret));
+            return ret;
+        }
+    }
+
+    if (vbasedev->vm_running) {
+        ret = vfio_migration_set_state(vbasedev,
+                         VFIO_DEVICE_STATE_RUNNING | VFIO_DEVICE_STATE_SAVING);
+        if (ret) {
+            error_report("Failed to set state RUNNING and SAVING");
+            return ret;
+        }
+    } else {
+        ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_SAVING);
+        if (ret) {
+            error_report("Failed to set state STOP and SAVING");
+            return ret;
+        }
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    return 0;
+}
+
+static void vfio_save_cleanup(void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+
+    if (migration->region.buffer.mmaps) {
+        vfio_region_unmap(&migration->region.buffer);
+    }
+}
+
+static SaveVMHandlers savevm_vfio_handlers = {
+    .save_setup = vfio_save_setup,
+    .save_cleanup = vfio_save_cleanup,
+};
+
+/* ---------------------------------------------------------------------- */
+
 static void vfio_vmstate_change(void *opaque, int running, RunState state)
 {
     VFIODevice *vbasedev = opaque;
@@ -169,7 +243,7 @@ static int vfio_migration_init(VFIODevice *vbasedev,
     }
 
     qemu_mutex_init(&vbasedev->migration->lock);
-
+    register_savevm_live(NULL, "vfio", -1, 1, &savevm_vfio_handlers, vbasedev);
     vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change,
                                                           vbasedev);
 
-- 
2.7.0