For now a naming nit and a question.
On Thu, Oct 16, 2025 at 7:44 AM Vladimir Sementsov-Ogievskiy
<[email protected]> wrote:
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
> ---
> hw/virtio/vhost-user.c | 95 ++++++++++++++++++++++++++++++++++
> include/hw/virtio/vhost-user.h | 4 ++
> 2 files changed, 99 insertions(+)
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index c5cb5ed528..a820214188 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -28,6 +28,8 @@
> #include "system/runstate.h"
> #include "system/cryptodev.h"
> #include "migration/postcopy-ram.h"
> +#include "migration/qemu-file-types.h"
> +#include "migration/qemu-file.h"
> #include "trace.h"
> #include "system/ramblock.h"
>
> @@ -3137,6 +3139,99 @@ void vhost_user_qmp_status(struct vhost_dev *dev,
> VirtioStatus *status)
> qmp_decode_protocols(u->protocol_features);
> }
>
> +typedef struct VhostUserMigTmp {
> + struct vhost_dev *parent;
> + bool has_backend_channel;
> + int backend_fd;
> + uint32_t memory_slots;
> + uint64_t protocol_features;
> +} VhostUserMigTmp;
> +
> +static int vhost_user_tmp_pre_save(void *opaque)
> +{
> + VhostUserMigTmp *tmp = opaque;
> + struct vhost_dev *dev = tmp->parent;
> + struct vhost_user *u = dev->opaque;
> + QIOChannelSocket *sioc = u->backend_sioc;
> +
> + if (sioc && sioc->fd < 0) {
> + return -EINVAL;
> + }
> +
> + tmp->backend_fd = sioc ? sioc->fd : -1;
> + tmp->has_backend_channel = !!sioc;
> + tmp->memory_slots = u->user->memory_slots;
> + tmp->protocol_features = u->protocol_features;
> +
> + return 0;
> +}
> +
> +static int vhost_user_tmp_post_load(void *opaque, int version_id)
> +{
> + struct VhostUserMigTmp *tmp = opaque;
> + struct vhost_dev *dev = tmp->parent;
> + struct vhost_user *u = dev->opaque;
> + Error *local_err = NULL;
> +
> + if (tmp->has_backend_channel) {
> + u->backend_sioc = qio_channel_socket_new_fd(tmp->backend_fd,
> + &local_err);
> + if (!u->backend_sioc) {
> + error_report_err(local_err);
> + return -EINVAL;
> + }
> + u->backend_src = qio_channel_add_watch_source(
> + QIO_CHANNEL(u->backend_sioc), G_IO_IN | G_IO_HUP,
> + backend_read, u->dev, NULL, NULL);
> + }
> +
> + u->user->memory_slots = tmp->memory_slots;
> + u->protocol_features = tmp->protocol_features;
> +
> + return 0;
> +}
> +
> +static bool vhost_user_tmp_test_fd(void *opaque, int version_id)
> +{
> + struct VhostUserMigTmp *tmp = opaque;
> +
> + return tmp->has_backend_channel;
> +}
> +
Will this be vhost-user-blk specific? It should probably be something
like vhost_user_backend_transfer_tmp?
> +static const VMStateDescription vmstate_vhost_user_blk_tmp = {
> + .name = "vhost-user-blk-tmp",
> + .pre_save = vhost_user_tmp_pre_save,
> + .post_load = vhost_user_tmp_post_load,
> + .fields = (const VMStateField[]) {
> + VMSTATE_UINT64(protocol_features, VhostUserMigTmp),
> + VMSTATE_UINT32(memory_slots, VhostUserMigTmp),
> + VMSTATE_BOOL(has_backend_channel, VhostUserMigTmp),
> + VMSTATE_FD_TEST(backend_fd, VhostUserMigTmp, vhost_user_tmp_test_fd),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> +static int vhost_user_post_load(void *opaque, int version_id)
> +{
> + struct vhost_dev *dev = opaque;
> + struct vhost_user *u = dev->opaque;
> +
> + u->postcopy_notifier.notify = vhost_user_postcopy_notifier;
> + postcopy_add_notifier(&u->postcopy_notifier);
> +
> + return 0;
> +}
> +
Why do we need a second post_load() callback here? Why can't
u->postcopy_notifier.notify be set in vhost_user_tmp_post_load()?
> +const VMStateDescription vmstate_vhost_user = {
> + .name = "vhost-user",
> + .post_load = vhost_user_post_load,
> + .fields = (const VMStateField[]) {
> + VMSTATE_WITH_TMP(struct vhost_dev, VhostUserMigTmp,
> + vmstate_vhost_user_blk_tmp),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> const VhostOps user_ops = {
> .backend_type = VHOST_BACKEND_TYPE_USER,
> .vhost_backend_init = vhost_user_backend_init,
> diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
> index 36d96296a3..fb89268de2 100644
> --- a/include/hw/virtio/vhost-user.h
> +++ b/include/hw/virtio/vhost-user.h
> @@ -114,4 +114,8 @@ void vhost_user_async_close(DeviceState *d,
>
> void vhost_user_qmp_status(struct vhost_dev *dev, VirtioStatus *status);
>
> +extern const VMStateDescription vmstate_vhost_user;
> +#define VMSTATE_BACKEND_TRANSFER_VHOST_USER(_field, _state) \
> + VMSTATE_STRUCT(_field, _state, 0, vmstate_vhost_user, struct vhost_dev)
> +
> #endif
> --
> 2.48.1
>
>
