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[Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring
From: |
wexu |
Subject: |
[Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring |
Date: |
Tue, 5 Jun 2018 15:08:00 -0400 |
From: Wei Xu <address@hidden>
Signed-off-by: Wei Xu <address@hidden>
---
hw/virtio/virtio.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 144 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index cdbb5af..0160d03 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1041,7 +1041,7 @@ static void *virtqueue_alloc_element(size_t sz, unsigned
out_num, unsigned in_nu
return elem;
}
-void *virtqueue_pop(VirtQueue *vq, size_t sz)
+static void *virtqueue_split_pop(VirtQueue *vq, size_t sz)
{
unsigned int i, head, max;
VRingMemoryRegionCaches *caches;
@@ -1176,6 +1176,149 @@ err_undo_map:
goto done;
}
+static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz)
+{
+ unsigned int i, head, max;
+ VRingMemoryRegionCaches *caches;
+ MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
+ MemoryRegionCache *cache;
+ int64_t len;
+ VirtIODevice *vdev = vq->vdev;
+ VirtQueueElement *elem = NULL;
+ unsigned out_num, in_num, elem_entries;
+ hwaddr addr[VIRTQUEUE_MAX_SIZE];
+ struct iovec iov[VIRTQUEUE_MAX_SIZE];
+ VRingDescPacked desc;
+
+ if (unlikely(vdev->broken)) {
+ return NULL;
+ }
+
+ rcu_read_lock();
+ if (virtio_queue_packed_empty_rcu(vq)) {
+ goto done;
+ }
+
+ /* When we start there are none of either input nor output. */
+ out_num = in_num = elem_entries = 0;
+
+ max = vq->vring.num;
+
+ if (vq->inuse >= vq->vring.num) {
+ virtio_error(vdev, "Virtqueue size exceeded");
+ goto done;
+ }
+
+ if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
+ /* FIXME: TBD */
+ }
+
+ head = vq->last_avail_idx;
+ i = head;
+
+ caches = vring_get_region_caches(vq);
+ cache = &caches->desc;
+ vring_packed_desc_read(vdev, &desc, cache, i);
+ if (desc.flags & VRING_DESC_F_INDIRECT) {
+ if (desc.len % sizeof(VRingDescPacked)) {
+ virtio_error(vdev, "Invalid size for indirect buffer table");
+ goto done;
+ }
+
+ /* loop over the indirect descriptor table */
+ len = address_space_cache_init(&indirect_desc_cache, vdev->dma_as,
+ desc.addr, desc.len, false);
+ cache = &indirect_desc_cache;
+ if (len < desc.len) {
+ virtio_error(vdev, "Cannot map indirect buffer");
+ goto done;
+ }
+
+ max = desc.len / sizeof(VRingDescPacked);
+ i = 0;
+ vring_packed_desc_read(vdev, &desc, cache, i);
+ }
+
+ /* Collect all the descriptors */
+ while (1) {
+ bool map_ok;
+
+ if (desc.flags & VRING_DESC_F_WRITE) {
+ map_ok = virtqueue_map_desc(vdev, &in_num, addr + out_num,
+ iov + out_num,
+ VIRTQUEUE_MAX_SIZE - out_num, true,
+ desc.addr, desc.len);
+ } else {
+ if (in_num) {
+ virtio_error(vdev, "Incorrect order for descriptors");
+ goto err_undo_map;
+ }
+ map_ok = virtqueue_map_desc(vdev, &out_num, addr, iov,
+ VIRTQUEUE_MAX_SIZE, false,
+ desc.addr, desc.len);
+ }
+ if (!map_ok) {
+ goto err_undo_map;
+ }
+
+ /* If we've got too many, that implies a descriptor loop. */
+ if (++elem_entries > max) {
+ virtio_error(vdev, "Looped descriptor");
+ goto err_undo_map;
+ }
+
+ if (++i >= vq->vring.num) {
+ i -= vq->vring.num;
+ }
+
+ if (desc.flags & VRING_DESC_F_NEXT) {
+ vring_packed_desc_read(vq->vdev, &desc, cache, i);
+ } else {
+ break;
+ }
+ }
+
+ /* Now copy what we have collected and mapped */
+ elem = virtqueue_alloc_element(sz, out_num, in_num);
+ for (i = 0; i < out_num; i++) {
+ elem->out_addr[i] = addr[i];
+ elem->out_sg[i] = iov[i];
+ }
+ for (i = 0; i < in_num; i++) {
+ elem->in_addr[i] = addr[head + out_num + i];
+ elem->in_sg[i] = iov[out_num + i];
+ }
+
+ vq->last_avail_idx += (cache == &indirect_desc_cache) ?
+ 1 : out_num + in_num;
+ if (vq->last_avail_idx >= vq->vring.num) {
+ vq->last_avail_idx -= vq->vring.num;
+ vq->avail_wrap_counter = !vq->avail_wrap_counter;
+ }
+ vq->inuse++;
+
+ trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
+done:
+ address_space_cache_destroy(&indirect_desc_cache);
+ rcu_read_unlock();
+
+ return elem;
+
+err_undo_map:
+ virtqueue_undo_map_desc(out_num, in_num, iov);
+ g_free(elem);
+ goto done;
+}
+
+void *virtqueue_pop(VirtQueue *vq, size_t sz)
+{
+ if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+ return virtqueue_packed_pop(vq, sz);
+ } else {
+ return virtqueue_split_pop(vq, sz);
+ }
+}
+
/* virtqueue_drop_all:
* @vq: The #VirtQueue
* Drops all queued buffers and indicates them to the guest
--
1.8.3.1
- [Qemu-devel] [RFC v2 1/8] virtio: feature bit, data structure, init for 1.1, (continued)
- [Qemu-devel] [RFC v2 1/8] virtio: feature bit, data structure, init for 1.1, wexu, 2018/06/05
- [Qemu-devel] [RFC v2 2/8] virtio: memory cache for packed ring, wexu, 2018/06/05
- [Qemu-devel] [RFC v2 3/8] virtio: empty check and desc read for packed ring, wexu, 2018/06/05
- [Qemu-devel] [RFC v2 4/8] virtio: get avail bytes check for packed ring, wexu, 2018/06/05
- [Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring,
wexu <=
[Qemu-devel] [RFC v2 6/8] virtio: flush/push for packed ring, wexu, 2018/06/05
[Qemu-devel] [RFC v2 8/8] virtio: guest driver reload for vhost-net, wexu, 2018/06/05
[Qemu-devel] [RFC v2 7/8] virtio: event suppression for packed ring, wexu, 2018/06/05