vhost: Check for queue full at vhost_svq_add
The series need to expose vhost_svq_add with full functionality, including checking for full queue. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
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@ -233,21 +233,29 @@ static void vhost_svq_kick(VhostShadowVirtqueue *svq)
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* Add an element to a SVQ.
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*
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* The caller must check that there is enough slots for the new element. It
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* takes ownership of the element: In case of failure, it is free and the SVQ
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* is considered broken.
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* takes ownership of the element: In case of failure not ENOSPC, it is free.
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*
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* Return -EINVAL if element is invalid, -ENOSPC if dev queue is full
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*/
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static bool vhost_svq_add(VhostShadowVirtqueue *svq, VirtQueueElement *elem)
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static int vhost_svq_add(VhostShadowVirtqueue *svq, VirtQueueElement *elem)
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{
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unsigned qemu_head;
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bool ok = vhost_svq_add_split(svq, elem, &qemu_head);
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unsigned ndescs = elem->in_num + elem->out_num;
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bool ok;
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if (unlikely(ndescs > vhost_svq_available_slots(svq))) {
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return -ENOSPC;
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}
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ok = vhost_svq_add_split(svq, elem, &qemu_head);
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if (unlikely(!ok)) {
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g_free(elem);
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return false;
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return -EINVAL;
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}
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svq->ring_id_maps[qemu_head] = elem;
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vhost_svq_kick(svq);
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return true;
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return 0;
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}
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/**
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@ -274,7 +282,7 @@ static void vhost_handle_guest_kick(VhostShadowVirtqueue *svq)
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while (true) {
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VirtQueueElement *elem;
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bool ok;
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int r;
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if (svq->next_guest_avail_elem) {
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elem = g_steal_pointer(&svq->next_guest_avail_elem);
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@ -286,25 +294,24 @@ static void vhost_handle_guest_kick(VhostShadowVirtqueue *svq)
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break;
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}
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if (elem->out_num + elem->in_num > vhost_svq_available_slots(svq)) {
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/*
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* This condition is possible since a contiguous buffer in GPA
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* does not imply a contiguous buffer in qemu's VA
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* scatter-gather segments. If that happens, the buffer exposed
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* to the device needs to be a chain of descriptors at this
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* moment.
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*
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* SVQ cannot hold more available buffers if we are here:
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* queue the current guest descriptor and ignore further kicks
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* until some elements are used.
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*/
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svq->next_guest_avail_elem = elem;
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return;
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}
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r = vhost_svq_add(svq, elem);
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if (unlikely(r != 0)) {
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if (r == -ENOSPC) {
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/*
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* This condition is possible since a contiguous buffer in
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* GPA does not imply a contiguous buffer in qemu's VA
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* scatter-gather segments. If that happens, the buffer
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* exposed to the device needs to be a chain of descriptors
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* at this moment.
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*
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* SVQ cannot hold more available buffers if we are here:
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* queue the current guest descriptor and ignore kicks
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* until some elements are used.
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*/
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svq->next_guest_avail_elem = elem;
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}
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ok = vhost_svq_add(svq, elem);
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if (unlikely(!ok)) {
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/* VQ is broken, just return and ignore any other kicks */
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/* VQ is full or broken, just return and ignore kicks */
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return;
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}
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}
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