在 2021/10/1 下午3:05, Eugenio Pérez 写道:
This will make qemu aware of the device used buffers, allowing it to
write the guest memory with its contents if needed.
Since the use of vhost_virtqueue_start can unmasks and discard call
events, vhost_virtqueue_start should be modified in one of these ways:
* Split in two: One of them uses all logic to start a queue with no
side effects for the guest, and another one tha actually assumes that
the guest has just started the device. Vdpa should use just the
former.
* Actually store and check if the guest notifier is masked, and do it
conditionally.
* Left as it is, and duplicate all the logic in vhost-vdpa.
Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
---
hw/virtio/vhost-shadow-virtqueue.c | 19 +++++++++++++++
hw/virtio/vhost-vdpa.c | 38 +++++++++++++++++++++++++++++-
2 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 21dc99ab5d..3fe129cf63 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -53,6 +53,22 @@ static void vhost_handle_guest_kick(EventNotifier *n)
event_notifier_set(&svq->kick_notifier);
}
+/* Forward vhost notifications */
+static void vhost_svq_handle_call_no_test(EventNotifier *n)
+{
+ VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue,
+ call_notifier);
+
+ event_notifier_set(&svq->guest_call_notifier);
+}
+
+static void vhost_svq_handle_call(EventNotifier *n)
+{
+ if (likely(event_notifier_test_and_clear(n))) {
+ vhost_svq_handle_call_no_test(n);
+ }
+}
+
/*
* Obtain the SVQ call notifier, where vhost device notifies SVQ that there
* exists pending used buffers.
@@ -180,6 +196,8 @@ VhostShadowVirtqueue *vhost_svq_new(struct vhost_dev *dev, int idx)
}
svq->vq = virtio_get_queue(dev->vdev, vq_idx);
+ event_notifier_set_handler(&svq->call_notifier,
+ vhost_svq_handle_call);
return g_steal_pointer(&svq);
err_init_call_notifier:
@@ -195,6 +213,7 @@ err_init_kick_notifier:
void vhost_svq_free(VhostShadowVirtqueue *vq)
{
event_notifier_cleanup(&vq->kick_notifier);
+ event_notifier_set_handler(&vq->call_notifier, NULL);
event_notifier_cleanup(&vq->call_notifier);
g_free(vq);
}
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index bc34de2439..6c5f4c98b8 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -712,13 +712,40 @@ static bool vhost_vdpa_svq_start_vq(struct vhost_dev *dev, unsigned idx)
{
struct vhost_vdpa *v = dev->opaque;
VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, idx);
- return vhost_svq_start(dev, idx, svq);
+ EventNotifier *vhost_call_notifier = vhost_svq_get_svq_call_notifier(svq);
+ struct vhost_vring_file vhost_call_file = {
+ .index = idx + dev->vq_index,
+ .fd = event_notifier_get_fd(vhost_call_notifier),
+ };
+ int r;
+ bool b;
+
+ /* Set shadow vq -> guest notifier */
+ assert(v->call_fd[idx]);
We need aovid the asser() here. On which case we can hit this?
+ vhost_svq_set_guest_call_notifier(svq, v->call_fd[idx]);
+
+ b = vhost_svq_start(dev, idx, svq);
+ if (unlikely(!b)) {
+ return false;
+ }
+
+ /* Set device -> SVQ notifier */
+ r = vhost_vdpa_set_vring_dev_call(dev, &vhost_call_file);
+ if (unlikely(r)) {
+ error_report("vhost_vdpa_set_vring_call for shadow vq failed");
+ return false;
+ }
Similar to kick, do we need to set_vring_call() before vhost_svq_start()?
+
+ /* Check for pending calls */
+ event_notifier_set(vhost_call_notifier);
Interesting, can this result spurious interrupt?
+ return true;
}
static unsigned vhost_vdpa_enable_svq(struct vhost_vdpa *v, bool enable)
{
struct vhost_dev *hdev = v->dev;
unsigned n;
+ int r;
if (enable == v->shadow_vqs_enabled) {
return hdev->nvqs;
@@ -752,9 +779,18 @@ static unsigned vhost_vdpa_enable_svq(struct vhost_vdpa *v, bool enable)
if (!enable) {
/* Disable all queues or clean up failed start */
for (n = 0; n < v->shadow_vqs->len; ++n) {
+ struct vhost_vring_file file = {
+ .index = vhost_vdpa_get_vq_index(hdev, n),
+ .fd = v->call_fd[n],
+ };
+
+ r = vhost_vdpa_set_vring_call(hdev, &file);
+ assert(r == 0);
+
unsigned vq_idx = vhost_vdpa_get_vq_index(hdev, n);
VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, n);
vhost_svq_stop(hdev, n, svq);
+ /* TODO: This can unmask or override call fd! */
I don't get this comment. Does this mean the current code can't work
with mask_notifiers? If yes, this is something we need to fix.
Thanks
vhost_virtqueue_start(hdev, hdev->vdev, &hdev->vqs[n], vq_idx);
}
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