From: Wei Xu <w...@redhat.com>
cloned from split ring pop, a global static length array
and the inside-element length array are introduced to
easy prototype, this consumes more memory and it is valuable
to move to dynamic allocation as the out/in sg does.
Signed-off-by: Wei Xu <w...@redhat.com>
---
hw/virtio/virtio.c | 154 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 153 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index cf726f3..0eafb38 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1221,7 +1221,7 @@ 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_pop_split(VirtQueue *vq, size_t sz)
{
unsigned int i, head, max;
VRingMemoryRegionCaches *caches;
@@ -1356,6 +1356,158 @@ err_undo_map:
goto done;
}
+static uint16_t dma_len[VIRTQUEUE_MAX_SIZE];
+static void *virtqueue_pop_packed(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;
+ uint8_t wrap_counter;
+
+ if (unlikely(vdev->broken)) {
+ return NULL;
+ }
+
+ vq->last_avail_idx %= vq->packed.num;
+
+ rcu_read_lock();
+ if (virtio_queue_empty_packed_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_packed;
+ vring_desc_read_packed(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_desc_read_packed(vdev, &desc, cache, i);
+ }
+
+ wrap_counter = vq->wrap_counter;
+ /* 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;
+ }
+
+ dma_len[i++] = desc.len;
+ /* Toggle wrap_counter for non indirect desc */
+ if ((i == vq->packed.num) && (cache != &indirect_desc_cache)) {
+ vq->wrap_counter ^= 1;
+ }
+
+ if (desc.flags & VRING_DESC_F_NEXT) {
+ vring_desc_read_packed(vq->vdev, &desc, cache, i % vq->packed.num);
+ } else {
+ break;
+ }
+ }
+
+ /* Now copy what we have collected and mapped */
+ elem = virtqueue_alloc_element(sz, out_num, in_num);
+ elem->index = head;
+ elem->wrap_counter = wrap_counter;
+ elem->count = (cache == &indirect_desc_cache) ? 1 : out_num + in_num;
+ for (i = 0; i < out_num; i++) {
+ /* DMA Done by marking the length as 0 */
+ elem->len[i] = 0;
+ elem->out_addr[i] = addr[i];
+ elem->out_sg[i] = iov[i];
+ }
+ for (i = 0; i < in_num; i++) {
+ elem->len[out_num + i] = dma_len[head + out_num + i];
+ elem->in_addr[i] = addr[out_num + i];
+ elem->in_sg[i] = iov[out_num + i];
+ }
+
+ vq->last_avail_idx += elem->count;
+ vq->last_avail_idx %= vq->packed.num;
+ vq->inuse += elem->count;
+
+ 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_pop_packed(vq, sz);
+ } else {
+ return virtqueue_pop_split(vq, sz);
+ }
+}
+
/* virtqueue_drop_all:
* @vq: The #VirtQueue
* Drops all queued buffers and indicates them to the guest
--
2.7.4
