[RFC v2 10/10] vhost: Support vduse suspend feature

Eugenio Pérez
2026-03-10T19:18:05Z

From: Super User <root@wsfd-advnetlab45.anl.eng.rdu2.dc.redhat.com>

Add support for the VDUSE_F_SUSPEND feature.

The suspend feature allows the driver to stop the device from processing
the virtqueues. This ensures that the virtqueue state can be fetched
reliably in a live migration.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
v2:
* Following latest comments on kernel series about VDUSE features, not
checking API version but only check if VDUSE_GET_FEATURES success.
---
lib/vhost/vduse.c | 33 ++++++++++++++++++++++++++++++++-
lib/vhost/vhost.h | 1 +
2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
index f62cc3189076..10de13f05277 100644
--- a/lib/vhost/vduse.c
+++ b/lib/vhost/vduse.c
@@ -46,7 +46,8 @@ static const char * const vduse_reqs_str[] = {
(id < RTE_DIM(vduse_reqs_str) ? \
vduse_reqs_str[id] : "Unknown")

-static const uint64_t supported_vduse_features = RTE_BIT64(VDUSE_F_QUEUE_READY);
+static const uint64_t supported_vduse_features =
+ RTE_BIT64(VDUSE_F_QUEUE_READY) | RTE_BIT64(VDUSE_F_SUSPEND);

static uint64_t vduse_vq_to_group(struct virtio_net *dev, struct vhost_virtqueue *vq)
{
@@ -520,6 +521,12 @@ vduse_events_handler(int fd, void *arg, int *close __rte_unused)
resp.result = VDUSE_REQ_RESULT_FAILED;
break;
}
+ if (dev->vduse_suspended) {
+ VHOST_CONFIG_LOG(dev->ifname, ERR,
+ "SET_VQ_READY received on suspended device");
+ resp.result = VDUSE_REQ_RESULT_FAILED;
+ break;
+ }

i = req.vq_ready.num;
vq = dev->virtqueue[i];
@@ -543,6 +550,30 @@ vduse_events_handler(int fd, void *arg, int *close __rte_unused)
vq->enabled = req.vq_ready.ready;
resp.result = VDUSE_REQ_RESULT_OK;
break;
+ case VDUSE_SUSPEND:
+ if (!(dev->vduse_features & RTE_BIT64(VDUSE_F_SUSPEND))) {
+ VHOST_CONFIG_LOG(dev->ifname, ERR,
+ "Unnegotiated suspend message");
+ resp.result = VDUSE_REQ_RESULT_FAILED;
+ break;
+ }
+ if (!(dev->status & VIRTIO_DEVICE_STATUS_DRIVER_OK)) {
+ VHOST_CONFIG_LOG(dev->ifname, ERR,
+ "Unexpected suspend message with no DRIVER_OK");
+ resp.result = VDUSE_REQ_RESULT_FAILED;
+ break;
+ }
+ for (i = 0; dev->notify_ops->vring_state_changed &&
+ i < dev->nr_vring; i++) {
+ if (dev->virtqueue[i] == dev->cvq)
+ continue;
+
+ dev->notify_ops->vring_state_changed(dev->vid, i, false);
+ }
+ dev->vduse_suspended = true;
+ resp.result = VDUSE_REQ_RESULT_OK;
+ break;
+
default:
resp.result = VDUSE_REQ_RESULT_FAILED;
break;
diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
index ce2e1a271c6f..73f0c9397cd0 100644
--- a/lib/vhost/vhost.h
+++ b/lib/vhost/vhost.h
@@ -534,6 +534,7 @@ struct __rte_cache_aligned virtio_net {
int vduse_dev_fd;
uint64_t vduse_api_ver;
uint64_t vduse_features;
+ bool vduse_suspended;

struct vhost_virtqueue *cvq;

--
2.53.0