Introduce vhost_dev.backend_transfer field,
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
hw/virtio/vhost.c | 121 +++++++++++++++++++++++++++++++++-----
include/hw/virtio/vhost.h | 7 +++
2 files changed, 113 insertions(+), 15 deletions(-)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 63036f8214..c46203eb9c 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1325,6 +1325,8 @@ out:
return ret;
}
+static void vhost_virtqueue_error_notifier(EventNotifier *n);
+
int vhost_virtqueue_start(struct vhost_dev *dev,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
@@ -1350,7 +1352,13 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
return r;
}
- vq->num = state.num = virtio_queue_get_num(vdev, idx);
+ vq->num = virtio_queue_get_num(vdev, idx);
+
+ if (dev->backend_transfer) {
+ return 0;
+ }
+
+ state.num = vq->num;
r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
if (r) {
VHOST_OPS_DEBUG(r, "vhost_set_vring_num failed");
@@ -1428,6 +1436,10 @@ static int do_vhost_virtqueue_stop(struct vhost_dev *dev,
trace_vhost_virtque_stop_in(dev, vdev->name, idx);
+ if (dev->backend_transfer) {
+ return 0;
+ }
+
if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
/* Don't stop the virtqueue which might have not been started */
return 0;
@@ -1565,10 +1577,14 @@ fail_call:
static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
{
- event_notifier_cleanup(&vq->masked_notifier);
+ if (!vq->dev->backend_transfer) {
+ event_notifier_cleanup(&vq->masked_notifier);
+ }
if (vq->dev->vhost_ops->vhost_set_vring_err) {
event_notifier_set_handler(&vq->error_notifier, NULL);
- event_notifier_cleanup(&vq->error_notifier);
+ if (!vq->dev->backend_transfer) {
+ event_notifier_cleanup(&vq->error_notifier);
+ }
}
}
@@ -1635,6 +1651,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
hdev->vdev = NULL;
hdev->migration_blocker = NULL;
+ hdev->_features_wait_incoming = true;
hdev->busyloop_timeout = busyloop_timeout;
for (i = 0; i < hdev->nvqs; ++i) {
@@ -1717,6 +1734,8 @@ int vhost_dev_connect(struct vhost_dev *hdev, Error **errp)
goto fail;
}
+ hdev->_features_wait_incoming = false;
+
for (i = 0; i < hdev->nvqs; ++i, ++n_initialized_vqs) {
r = vhost_virtqueue_connect(hdev->vqs + i, hdev->vq_index + i);
if (r < 0) {
@@ -1808,8 +1827,11 @@ void vhost_dev_disable_notifiers_nvqs(struct vhost_dev *hdev,
*/
memory_region_transaction_commit();
- for (i = 0; i < nvqs; ++i) {
- virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
+ if (!hdev->backend_transfer) {
+ for (i = 0; i < nvqs; ++i) {
+ virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus),
+ hdev->vq_index + i);
+ }
}
virtio_device_release_ioeventfd(vdev);
}
@@ -1967,6 +1989,11 @@ void vhost_get_features_ex(struct vhost_dev *hdev,
{
const int *bit = feature_bits;
+ if (hdev->_features_wait_incoming) {
+ /* Excessive set is enough for early initialization. */
+ return;
+ }
+
while (*bit != VHOST_INVALID_FEATURE_BIT) {
if (!vhost_dev_has_feature_ex(hdev, *bit)) {
virtio_clear_feature_ex(features, *bit);
@@ -2001,6 +2028,54 @@ const VMStateDescription vmstate_backend_transfer_vhost_inflight = {
}
};
+const VMStateDescription vmstate_vhost_virtqueue = {
+ .name = "vhost-virtqueue",
+ .fields = (const VMStateField[]) {
+ VMSTATE_EVENT_NOTIFIER(error_notifier, struct vhost_virtqueue),
+ VMSTATE_EVENT_NOTIFIER(masked_notifier, struct vhost_virtqueue),
+ VMSTATE_END_OF_LIST()
+ },
+};
+
+static int vhost_dev_post_load(void *opaque, int version_id)
+{
+ struct vhost_dev *hdev = opaque;
+ Error *err = NULL;
+ int i;
+
+ if (!check_memslots(hdev, &err)) {
+ error_report_err(err);
+ return -EINVAL;
+ }
+
+ hdev->_features_wait_incoming = false;
+
+ if (hdev->vhost_ops->vhost_set_vring_err) {
+ for (i = 0; i < hdev->nvqs; ++i) {
+ event_notifier_set_handler(&hdev->vqs[i].error_notifier,
+ vhost_virtqueue_error_notifier);
+ }
+ }
+
+
+ return 0;
+}
+
+const VMStateDescription vmstate_vhost_dev = {
+ .name = "vhost-dev",
+ .post_load = vhost_dev_post_load,
+ .fields = (const VMStateField[]) {
+ VMSTATE_UINT64(_features, struct vhost_dev),
+ VMSTATE_UINT64(max_queues, struct vhost_dev),
+ VMSTATE_UINT32_EQUAL(nvqs, struct vhost_dev, NULL),
+ VMSTATE_STRUCT_VARRAY_POINTER_UINT32(vqs, struct vhost_dev,
+ nvqs,
+ vmstate_vhost_virtqueue,
+ struct vhost_virtqueue),
+ VMSTATE_END_OF_LIST()
+ },
+};
+
void vhost_ack_features_ex(struct vhost_dev *hdev, const int *feature_bits,
const uint64_t *features)
{
@@ -2127,19 +2202,24 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
hdev->started = true;
hdev->vdev = vdev;
- r = vhost_dev_set_features(hdev, hdev->log_enabled);
- if (r < 0) {
- goto fail_features;
+ if (!hdev->backend_transfer) {
+ r = vhost_dev_set_features(hdev, hdev->log_enabled);
+ if (r < 0) {
+ warn_report("%s %d", __func__, __LINE__);
+ goto fail_features;
+ }
}
if (vhost_dev_has_iommu(hdev)) {
memory_listener_register(&hdev->iommu_listener, vdev->dma_as);
}
- r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
- if (r < 0) {
- VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
- goto fail_mem;
+ if (!hdev->backend_transfer) {
+ r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
+ if (r < 0) {
+ VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
+ goto fail_mem;
+ }
}
for (i = 0; i < hdev->nvqs; ++i) {
r = vhost_virtqueue_start(hdev,
@@ -2179,13 +2259,13 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
}
vhost_dev_elect_mem_logger(hdev, true);
}
- if (vrings) {
+ if (vrings && !hdev->backend_transfer) {
r = vhost_dev_set_vring_enable(hdev, true);
if (r) {
goto fail_log;
}
}
- if (hdev->vhost_ops->vhost_dev_start) {
+ if (hdev->vhost_ops->vhost_dev_start && !hdev->backend_transfer) {
r = hdev->vhost_ops->vhost_dev_start(hdev, true);
if (r) {
goto fail_start;
@@ -2207,6 +2287,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
}
vhost_start_config_intr(hdev);
+ hdev->backend_transfer = false;
+
trace_vhost_dev_start_out(hdev, vdev->name);
return 0;
fail_iotlb:
@@ -2262,9 +2344,18 @@ static int do_vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
if (hdev->vhost_ops->vhost_dev_start) {
hdev->vhost_ops->vhost_dev_start(hdev, false);
}
- if (vrings) {
+ if (vrings && !hdev->backend_transfer) {
vhost_dev_set_vring_enable(hdev, false);
}
+
+ if (hdev->backend_transfer) {
+ for (i = 0; i < hdev->nvqs; ++i) {
+ struct vhost_virtqueue *vq = hdev->vqs + i;
+
+ event_notifier_set_handler(&vq->error_notifier, NULL);
+ }
+ }
+
for (i = 0; i < hdev->nvqs; ++i) {
rc |= do_vhost_virtqueue_stop(hdev,
vdev,
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 94a0c75fc8..55ad822848 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -105,6 +105,9 @@ struct vhost_dev {
VIRTIO_DECLARE_FEATURES(_features);
VIRTIO_DECLARE_FEATURES(acked_features);
+ bool _features_wait_incoming;
+ bool backend_transfer;
+
uint32_t busyloop_timeout;
uint64_t max_queues;
uint64_t backend_cap;
@@ -592,4 +595,8 @@ extern const VMStateDescription vmstate_backend_transfer_vhost_inflight;
VMSTATE_STRUCT_POINTER(_field, _state, vmstate_inflight, \
struct vhost_inflight)
+extern const VMStateDescription vmstate_vhost_dev;
+#define VMSTATE_BACKEND_TRANSFER_VHOST(_field, _state) \
+ VMSTATE_STRUCT(_field, _state, 0, vmstate_vhost_dev, struct vhost_dev)
+
#endif
--
2.48.1Overall looks good. Just a nit.
Acked-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>
On Thu, Oct 16, 2025 at 7:44 AM Vladimir Sementsov-Ogievskiy
<vsementsov@yandex-team.ru> wrote:
>
> Introduce vhost_dev.backend_transfer field,
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
> hw/virtio/vhost.c | 121 +++++++++++++++++++++++++++++++++-----
> include/hw/virtio/vhost.h | 7 +++
> 2 files changed, 113 insertions(+), 15 deletions(-)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 63036f8214..c46203eb9c 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1325,6 +1325,8 @@ out:
> return ret;
> }
>
> +static void vhost_virtqueue_error_notifier(EventNotifier *n);
> +
> int vhost_virtqueue_start(struct vhost_dev *dev,
> struct VirtIODevice *vdev,
> struct vhost_virtqueue *vq,
> @@ -1350,7 +1352,13 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
> return r;
> }
>
> - vq->num = state.num = virtio_queue_get_num(vdev, idx);
> + vq->num = virtio_queue_get_num(vdev, idx);
> +
> + if (dev->backend_transfer) {
> + return 0;
> + }
> +
> + state.num = vq->num;
> r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
> if (r) {
> VHOST_OPS_DEBUG(r, "vhost_set_vring_num failed");
> @@ -1428,6 +1436,10 @@ static int do_vhost_virtqueue_stop(struct vhost_dev *dev,
>
> trace_vhost_virtque_stop_in(dev, vdev->name, idx);
>
> + if (dev->backend_transfer) {
> + return 0;
> + }
> +
> if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
> /* Don't stop the virtqueue which might have not been started */
> return 0;
> @@ -1565,10 +1577,14 @@ fail_call:
>
> static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
> {
> - event_notifier_cleanup(&vq->masked_notifier);
> + if (!vq->dev->backend_transfer) {
> + event_notifier_cleanup(&vq->masked_notifier);
> + }
> if (vq->dev->vhost_ops->vhost_set_vring_err) {
> event_notifier_set_handler(&vq->error_notifier, NULL);
> - event_notifier_cleanup(&vq->error_notifier);
> + if (!vq->dev->backend_transfer) {
> + event_notifier_cleanup(&vq->error_notifier);
> + }
> }
> }
>
> @@ -1635,6 +1651,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>
> hdev->vdev = NULL;
> hdev->migration_blocker = NULL;
> + hdev->_features_wait_incoming = true;
> hdev->busyloop_timeout = busyloop_timeout;
>
> for (i = 0; i < hdev->nvqs; ++i) {
> @@ -1717,6 +1734,8 @@ int vhost_dev_connect(struct vhost_dev *hdev, Error **errp)
> goto fail;
> }
>
> + hdev->_features_wait_incoming = false;
> +
> for (i = 0; i < hdev->nvqs; ++i, ++n_initialized_vqs) {
> r = vhost_virtqueue_connect(hdev->vqs + i, hdev->vq_index + i);
> if (r < 0) {
> @@ -1808,8 +1827,11 @@ void vhost_dev_disable_notifiers_nvqs(struct vhost_dev *hdev,
> */
> memory_region_transaction_commit();
>
> - for (i = 0; i < nvqs; ++i) {
> - virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
> + if (!hdev->backend_transfer) {
> + for (i = 0; i < nvqs; ++i) {
> + virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus),
> + hdev->vq_index + i);
> + }
> }
> virtio_device_release_ioeventfd(vdev);
> }
> @@ -1967,6 +1989,11 @@ void vhost_get_features_ex(struct vhost_dev *hdev,
> {
> const int *bit = feature_bits;
>
> + if (hdev->_features_wait_incoming) {
> + /* Excessive set is enough for early initialization. */
> + return;
> + }
> +
> while (*bit != VHOST_INVALID_FEATURE_BIT) {
> if (!vhost_dev_has_feature_ex(hdev, *bit)) {
> virtio_clear_feature_ex(features, *bit);
> @@ -2001,6 +2028,54 @@ const VMStateDescription vmstate_backend_transfer_vhost_inflight = {
> }
> };
>
> +const VMStateDescription vmstate_vhost_virtqueue = {
> + .name = "vhost-virtqueue",
> + .fields = (const VMStateField[]) {
> + VMSTATE_EVENT_NOTIFIER(error_notifier, struct vhost_virtqueue),
> + VMSTATE_EVENT_NOTIFIER(masked_notifier, struct vhost_virtqueue),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> +static int vhost_dev_post_load(void *opaque, int version_id)
> +{
> + struct vhost_dev *hdev = opaque;
> + Error *err = NULL;
> + int i;
> +
> + if (!check_memslots(hdev, &err)) {
> + error_report_err(err);
> + return -EINVAL;
> + }
> +
> + hdev->_features_wait_incoming = false;
> +
> + if (hdev->vhost_ops->vhost_set_vring_err) {
> + for (i = 0; i < hdev->nvqs; ++i) {
> + event_notifier_set_handler(&hdev->vqs[i].error_notifier,
> + vhost_virtqueue_error_notifier);
> + }
> + }
> +
nit: spurious newline
> +
> + return 0;
> +}
> +
> +const VMStateDescription vmstate_vhost_dev = {
> + .name = "vhost-dev",
> + .post_load = vhost_dev_post_load,
> + .fields = (const VMStateField[]) {
> + VMSTATE_UINT64(_features, struct vhost_dev),
> + VMSTATE_UINT64(max_queues, struct vhost_dev),
> + VMSTATE_UINT32_EQUAL(nvqs, struct vhost_dev, NULL),
> + VMSTATE_STRUCT_VARRAY_POINTER_UINT32(vqs, struct vhost_dev,
> + nvqs,
> + vmstate_vhost_virtqueue,
> + struct vhost_virtqueue),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> void vhost_ack_features_ex(struct vhost_dev *hdev, const int *feature_bits,
> const uint64_t *features)
> {
> @@ -2127,19 +2202,24 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
> hdev->started = true;
> hdev->vdev = vdev;
>
> - r = vhost_dev_set_features(hdev, hdev->log_enabled);
> - if (r < 0) {
> - goto fail_features;
> + if (!hdev->backend_transfer) {
> + r = vhost_dev_set_features(hdev, hdev->log_enabled);
> + if (r < 0) {
> + warn_report("%s %d", __func__, __LINE__);
> + goto fail_features;
> + }
> }
>
> if (vhost_dev_has_iommu(hdev)) {
> memory_listener_register(&hdev->iommu_listener, vdev->dma_as);
> }
>
> - r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
> - if (r < 0) {
> - VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
> - goto fail_mem;
> + if (!hdev->backend_transfer) {
> + r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
> + if (r < 0) {
> + VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
> + goto fail_mem;
> + }
> }
> for (i = 0; i < hdev->nvqs; ++i) {
> r = vhost_virtqueue_start(hdev,
> @@ -2179,13 +2259,13 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
> }
> vhost_dev_elect_mem_logger(hdev, true);
> }
> - if (vrings) {
> + if (vrings && !hdev->backend_transfer) {
> r = vhost_dev_set_vring_enable(hdev, true);
> if (r) {
> goto fail_log;
> }
> }
> - if (hdev->vhost_ops->vhost_dev_start) {
> + if (hdev->vhost_ops->vhost_dev_start && !hdev->backend_transfer) {
> r = hdev->vhost_ops->vhost_dev_start(hdev, true);
> if (r) {
> goto fail_start;
> @@ -2207,6 +2287,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
> }
> vhost_start_config_intr(hdev);
>
> + hdev->backend_transfer = false;
> +
> trace_vhost_dev_start_out(hdev, vdev->name);
> return 0;
> fail_iotlb:
> @@ -2262,9 +2344,18 @@ static int do_vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
> if (hdev->vhost_ops->vhost_dev_start) {
> hdev->vhost_ops->vhost_dev_start(hdev, false);
> }
> - if (vrings) {
> + if (vrings && !hdev->backend_transfer) {
> vhost_dev_set_vring_enable(hdev, false);
> }
> +
> + if (hdev->backend_transfer) {
> + for (i = 0; i < hdev->nvqs; ++i) {
> + struct vhost_virtqueue *vq = hdev->vqs + i;
> +
> + event_notifier_set_handler(&vq->error_notifier, NULL);
> + }
> + }
> +
> for (i = 0; i < hdev->nvqs; ++i) {
> rc |= do_vhost_virtqueue_stop(hdev,
> vdev,
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 94a0c75fc8..55ad822848 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -105,6 +105,9 @@ struct vhost_dev {
> VIRTIO_DECLARE_FEATURES(_features);
> VIRTIO_DECLARE_FEATURES(acked_features);
>
> + bool _features_wait_incoming;
> + bool backend_transfer;
> +
> uint32_t busyloop_timeout;
> uint64_t max_queues;
> uint64_t backend_cap;
> @@ -592,4 +595,8 @@ extern const VMStateDescription vmstate_backend_transfer_vhost_inflight;
> VMSTATE_STRUCT_POINTER(_field, _state, vmstate_inflight, \
> struct vhost_inflight)
>
> +extern const VMStateDescription vmstate_vhost_dev;
> +#define VMSTATE_BACKEND_TRANSFER_VHOST(_field, _state) \
> + VMSTATE_STRUCT(_field, _state, 0, vmstate_vhost_dev, struct vhost_dev)
> +
> #endif
> --
> 2.48.1
>
>
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