[PATCH v5 28/36] vfio/migration: Multifd device state transfer support - config loading support

[Maciej S. Szmigiero]

From: "Maciej S. Szmigiero" <maciej.szmigi...@oracle.com>

Load device config received via multifd using the existing machinery
behind vfio_load_device_config_state().

Also, make sure to process the relevant main migration channel flags.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigi...@oracle.com>
---
 hw/vfio/migration-multifd.c   | 47 ++++++++++++++++++++++++++++++++++-
 hw/vfio/migration.c           |  8 +++++-
 include/hw/vfio/vfio-common.h |  2 ++
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c
index b3a88c062769..7200f6f1c2a2 100644
--- a/hw/vfio/migration-multifd.c
+++ b/hw/vfio/migration-multifd.c
@@ -15,6 +15,7 @@
 #include "qemu/lockable.h"
 #include "qemu/main-loop.h"
 #include "qemu/thread.h"
+#include "io/channel-buffer.h"
 #include "migration/qemu-file.h"
 #include "migration-multifd.h"
 #include "trace.h"
@@ -186,7 +187,51 @@ bool vfio_load_state_buffer(void *opaque, char *data, 
size_t data_size,
 
 static int vfio_load_bufs_thread_load_config(VFIODevice *vbasedev)
 {
-    return -EINVAL;
+    VFIOMigration *migration = vbasedev->migration;
+    VFIOMultifd *multifd = migration->multifd;
+    VFIOStateBuffer *lb;
+    g_autoptr(QIOChannelBuffer) bioc = NULL;
+    QEMUFile *f_out = NULL, *f_in = NULL;
+    uint64_t mig_header;
+    int ret;
+
+    assert(multifd->load_buf_idx == multifd->load_buf_idx_last);
+    lb = vfio_state_buffers_at(&multifd->load_bufs, multifd->load_buf_idx);
+    assert(lb->is_present);
+
+    bioc = qio_channel_buffer_new(lb->len);
+    qio_channel_set_name(QIO_CHANNEL(bioc), "vfio-device-config-load");
+
+    f_out = qemu_file_new_output(QIO_CHANNEL(bioc));
+    qemu_put_buffer(f_out, (uint8_t *)lb->data, lb->len);
+
+    ret = qemu_fflush(f_out);
+    if (ret) {
+        g_clear_pointer(&f_out, qemu_fclose);
+        return ret;
+    }
+
+    qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
+    f_in = qemu_file_new_input(QIO_CHANNEL(bioc));
+
+    mig_header = qemu_get_be64(f_in);
+    if (mig_header != VFIO_MIG_FLAG_DEV_CONFIG_STATE) {
+        g_clear_pointer(&f_out, qemu_fclose);
+        g_clear_pointer(&f_in, qemu_fclose);
+        return -EINVAL;
+    }
+
+    bql_lock();
+    ret = vfio_load_device_config_state(f_in, vbasedev);
+    bql_unlock();
+
+    g_clear_pointer(&f_out, qemu_fclose);
+    g_clear_pointer(&f_in, qemu_fclose);
+    if (ret < 0) {
+        return ret;
+    }
+
+    return 0;
 }
 
 static VFIOStateBuffer *vfio_load_state_buffer_get(VFIOMultifd *multifd)
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 85f54cb22df2..b962309f7c27 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -264,7 +264,7 @@ static int vfio_save_device_config_state(QEMUFile *f, void 
*opaque,
     return ret;
 }
 
-static int vfio_load_device_config_state(QEMUFile *f, void *opaque)
+int vfio_load_device_config_state(QEMUFile *f, void *opaque)
 {
     VFIODevice *vbasedev = opaque;
     uint64_t data;
@@ -728,6 +728,12 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int 
version_id)
         switch (data) {
         case VFIO_MIG_FLAG_DEV_CONFIG_STATE:
         {
+            if (vfio_multifd_transfer_enabled(vbasedev)) {
+                error_report("%s: got DEV_CONFIG_STATE but doing multifd 
transfer",
+                             vbasedev->name);
+                return -EINVAL;
+            }
+
             return vfio_load_device_config_state(f, opaque);
         }
         case VFIO_MIG_FLAG_DEV_SETUP_STATE:
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index ab110198bd6b..ce2bdea8a2c2 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -298,6 +298,8 @@ void vfio_add_bytes_transferred(unsigned long val);
 bool vfio_device_state_is_running(VFIODevice *vbasedev);
 bool vfio_device_state_is_precopy(VFIODevice *vbasedev);
 
+int vfio_load_device_config_state(QEMUFile *f, void *opaque);
+
 #ifdef CONFIG_LINUX
 int vfio_get_region_info(VFIODevice *vbasedev, int index,
                          struct vfio_region_info **info);