[v4,26/33] vfio/migration: Multifd device state transfer support - receive init/cleanup

Commit Message

Maciej S. Szmigiero Jan. 30, 2025, 10:08 a.m. UTC

From: "Maciej S. Szmigiero" <[e-mail]>

Add support for VFIOMultifd data structure that will contain most of the
receive-side data together with its init/cleanup methods.

Signed-off-by: Maciej S. Szmigiero <[e-mail]>
---
 hw/vfio/migration.c           | 52 +++++++++++++++++++++++++++++++++--
 include/hw/vfio/vfio-common.h |  5 ++++
 2 files changed, 55 insertions(+), 2 deletions(-)

Patch

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 3211041939c6..bcdf204d5cf4 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -300,6 +300,9 @@  typedef struct VFIOStateBuffer {
     size_t len;
 } VFIOStateBuffer;
 
+typedef struct VFIOMultifd {
+} VFIOMultifd;
+
 static void vfio_state_buffer_clear(gpointer data)
 {
     VFIOStateBuffer *lb = data;
@@ -398,6 +401,18 @@  static int vfio_load_device_config_state(QEMUFile *f, void *opaque)
     return qemu_file_get_error(f);
 }
 
+static VFIOMultifd *vfio_multifd_new(void)
+{
+    VFIOMultifd *multifd = g_new(VFIOMultifd, 1);
+
+    return multifd;
+}
+
+static void vfio_multifd_free(VFIOMultifd *multifd)
+{
+    g_free(multifd);
+}
+
 static void vfio_migration_cleanup(VFIODevice *vbasedev)
 {
     VFIOMigration *migration = vbasedev->migration;
@@ -785,14 +800,47 @@  static void vfio_save_state(QEMUFile *f, void *opaque)
 static int vfio_load_setup(QEMUFile *f, void *opaque, Error **errp)
 {
     VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    int ret;
+
+    /*
+     * Make a copy of this setting at the start in case it is changed
+     * mid-migration.
+     */
+    if (vbasedev->migration_multifd_transfer == ON_OFF_AUTO_AUTO) {
+        migration->multifd_transfer = vfio_multifd_transfer_supported();
+    } else {
+        migration->multifd_transfer =
+            vbasedev->migration_multifd_transfer == ON_OFF_AUTO_ON;
+    }
+
+    if (migration->multifd_transfer && !vfio_multifd_transfer_supported()) {
+        error_setg(errp,
+                   "%s: Multifd device transfer requested but unsupported in the current config",
+                   vbasedev->name);
+        return -EINVAL;
+    }
+
+    ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_RESUMING,
+                                   migration->device_state, errp);
+    if (ret) {
+        return ret;
+    }
+
+    if (migration->multifd_transfer) {
+        assert(!migration->multifd);
+        migration->multifd = vfio_multifd_new();
+    }
 
-    return vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_RESUMING,
-                                    vbasedev->migration->device_state, errp);
+    return 0;
 }
 
 static int vfio_load_cleanup(void *opaque)
 {
     VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+
+    g_clear_pointer(&migration->multifd, vfio_multifd_free);
 
     vfio_migration_cleanup(vbasedev);
     trace_vfio_load_cleanup(vbasedev->name);
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 153d03745dc7..c0c9c0b1b263 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -61,6 +61,8 @@  typedef struct VFIORegion {
     uint8_t nr; /* cache the region number for debug */
 } VFIORegion;
 
+typedef struct VFIOMultifd VFIOMultifd;
+
 typedef struct VFIOMigration {
     struct VFIODevice *vbasedev;
     VMChangeStateEntry *vm_state;
@@ -72,6 +74,8 @@  typedef struct VFIOMigration {
     uint64_t mig_flags;
     uint64_t precopy_init_size;
     uint64_t precopy_dirty_size;
+    bool multifd_transfer;
+    VFIOMultifd *multifd;
     bool initial_data_sent;
 
     bool event_save_iterate_started;
@@ -133,6 +137,7 @@  typedef struct VFIODevice {
     bool no_mmap;
     bool ram_block_discard_allowed;
     OnOffAuto enable_migration;
+    OnOffAuto migration_multifd_transfer;
     OnOffAuto migration_load_config_after_iter;
     bool migration_events;
     VFIODeviceOps *ops;