On 2026/07/24 7:30, Connor Kite wrote:
By default svq vrings are placed in an anonymous memory map. As svqs
will be leveraged to enable memory isolation in vhost-user, it is useful
to be able to place the vrings in a shared isolation memory region.
Adds the option to specify vring placement by providing a vring base
address before starting the svq.
Signed-off-by: Connor Kite <[email protected]>
---
hw/virtio/vhost-shadow-virtqueue.c | 22 +++++++++++++++-------
hw/virtio/vhost-shadow-virtqueue.h | 3 +++
2 files changed, 18 insertions(+), 7 deletions(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.c
b/hw/virtio/vhost-shadow-virtqueue.c
index eb86c1ee37..9e3c359f50 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -857,14 +857,21 @@ void vhost_svq_start(VhostShadowVirtqueue *svq,
VirtIODevice *vdev,
svq->vring.num = virtio_queue_get_num(vdev, virtio_get_queue_index(vq));
svq->num_free = svq->vring.num;
- svq->vring.desc = mmap(NULL, vhost_svq_driver_area_size(svq),
- PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS,
- -1, 0);
desc_size = sizeof(vring_desc_t) * svq->vring.num;
- svq->vring.avail = (void *)((char *)svq->vring.desc + desc_size);
- svq->vring.used = mmap(NULL, vhost_svq_device_area_size(svq),
- PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS,
- -1, 0);
+ if (svq->base_addr == NULL) {
+ svq->vring.desc = mmap(NULL, vhost_svq_driver_area_size(svq),
+ PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS,
+ -1, 0);
+ svq->vring.avail = (void *)((char *)svq->vring.desc + desc_size);
+ svq->vring.used = mmap(NULL, vhost_svq_device_area_size(svq),
+ PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS,
+ -1, 0);
+ } else {
+ svq->vring.desc = (void *) svq->base_addr;
Nit: please remove the whitespace between (void *) and svq->base_addr.
+ svq->vring.avail = (void *)((char *)svq->vring.desc + desc_size);
+ svq->vring.used = (void *)((char *)svq->base_addr +
+ vhost_svq_driver_area_size(svq));
+ }
Unmapping svq here can lead to use-after-unmapping because the ring is
not stopped yet. do_vhost_dev_stop() calls do_vhost_virtqueue_stop()
only after calling hdev->vhost_ops->vhost_dev_start(hdev, false).
svq->desc_state = g_new0(SVQDescState, svq->vring.num);
if (virtio_vdev_has_feature(svq->vdev, VIRTIO_F_IN_ORDER)) {
svq->batch_last.id = VIRTIO_RING_NOT_IN_BATCH;
@@ -929,6 +936,7 @@ VhostShadowVirtqueue *vhost_svq_new(const
VhostShadowVirtqueueOps *ops,
event_notifier_init_fd(&svq->svq_kick, VHOST_FILE_UNBIND);
svq->ops = ops;
svq->ops_opaque = ops_opaque;
+ svq->base_addr = NULL;
return svq;
}
diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index ccfeee36d7..39f69e6455 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -148,6 +148,9 @@ typedef struct VhostShadowVirtqueue {
/* Size of SVQ vring free descriptors */
uint16_t num_free;
+
+ /* Location assigned to vrings if not in default anon memory map*/
Nit: here please add a whitespace before */
Regards,
Akihiko Odaki
+ hwaddr *base_addr;
} VhostShadowVirtqueue;
bool vhost_svq_valid_features(uint64_t features, Error **errp);
