Re: [Qemu-devel] [PATCH v1 09/16] virtio: fill/flush/pop for packed ring
On Fri, Nov 30, 2018 at 01:45:19PM +0100, Maxime Coquelin wrote:
> Hi Wei,
>
> On 11/22/18 3:06 PM, w...@redhat.com wrote:
> >+void virtqueue_flush(VirtQueue *vq, unsigned int count)
> >+{
> >+if (unlikely(vq->vdev->broken)) {
> >+vq->inuse -= count;
> >+return;
> >+}
> >+
> >+if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
> >+virtqueue_packed_flush(vq, count);
> >+} else {
> >+virtqueue_split_flush(vq, count);
> >+}
> >+}
> >+
> > void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
> > unsigned int len)
> > {
> >@@ -1074,7 +1180,7 @@ 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;
> >@@ -1089,9 +1195,6 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
> > VRingDesc desc;
> > int rc;
> >-if (unlikely(vdev->broken)) {
> >-return NULL;
> >-}
> > rcu_read_lock();
> > if (virtio_queue_empty_rcu(vq)) {
> > goto done;
> >@@ -1209,6 +1312,159 @@ 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];
> >+VRingPackedDesc desc;
> >+uint16_t id;
> >+
> >+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;
> >+}
> >+
> >+head = vq->last_avail_idx;
> >+i = head;
> >+
> >+caches = vring_get_region_caches(vq);
> >+cache = >desc;
> >+
> >+/* Empty check has been done at the beginning, so it is an available
> >+ * entry already, make sure all fields has been exposed by guest */
> >+smp_rmb();
> >+vring_packed_desc_read(vdev, , cache, i);
> >+
> >+id = desc.id;
> >+if (desc.flags & VRING_DESC_F_INDIRECT) {
> >+
> >+if (desc.len % sizeof(VRingPackedDesc)) {
> >+virtio_error(vdev, "Invalid size for indirect buffer table");
> >+goto done;
> >+}
> >+
> >+/* loop over the indirect descriptor table */
> >+len = address_space_cache_init(_desc_cache, vdev->dma_as,
> >+ desc.addr, desc.len, false);
> >+cache = _desc_cache;
> >+if (len < desc.len) {
> >+virtio_error(vdev, "Cannot map indirect buffer");
> >+goto done;
> >+}
> >+
> >+max = desc.len / sizeof(VRingPackedDesc);
> >+i = 0;
> >+vring_packed_desc_read(vdev, , cache, i);
> >+/* Make sure we see all the fields*/
> >+smp_rmb();
> >+}
> >+
> >+/* Collect all the descriptors */
> >+while (1) {
> >+bool map_ok;
> >+
> >+if (desc.flags & VRING_DESC_F_WRITE) {
> >+map_ok = virtqueue_map_desc(vdev, _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, _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, , cache, i);
> >+} else {
> >+break;
> >+}
> >+}
> >+
> >+/* Now copy what we have collected and mapped */
> >+elem = virtqueue_alloc_element(sz, out_num, in_num);
> >+
Re: [Qemu-devel] [PATCH v1 09/16] virtio: fill/flush/pop for packed ring
Hi Wei,
On 11/22/18 3:06 PM, w...@redhat.com wrote:
+void virtqueue_flush(VirtQueue *vq, unsigned int count)
+{
+if (unlikely(vq->vdev->broken)) {
+vq->inuse -= count;
+return;
+}
+
+if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+virtqueue_packed_flush(vq, count);
+} else {
+virtqueue_split_flush(vq, count);
+}
+}
+
void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
@@ -1074,7 +1180,7 @@ 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;
@@ -1089,9 +1195,6 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
VRingDesc desc;
int rc;
-if (unlikely(vdev->broken)) {
-return NULL;
-}
rcu_read_lock();
if (virtio_queue_empty_rcu(vq)) {
goto done;
@@ -1209,6 +1312,159 @@ 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];
+VRingPackedDesc desc;
+uint16_t id;
+
+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;
+}
+
+head = vq->last_avail_idx;
+i = head;
+
+caches = vring_get_region_caches(vq);
+cache = >desc;
+
+/* Empty check has been done at the beginning, so it is an available
+ * entry already, make sure all fields has been exposed by guest */
+smp_rmb();
+vring_packed_desc_read(vdev, , cache, i);
+
+id = desc.id;
+if (desc.flags & VRING_DESC_F_INDIRECT) {
+
+if (desc.len % sizeof(VRingPackedDesc)) {
+virtio_error(vdev, "Invalid size for indirect buffer table");
+goto done;
+}
+
+/* loop over the indirect descriptor table */
+len = address_space_cache_init(_desc_cache, vdev->dma_as,
+ desc.addr, desc.len, false);
+cache = _desc_cache;
+if (len < desc.len) {
+virtio_error(vdev, "Cannot map indirect buffer");
+goto done;
+}
+
+max = desc.len / sizeof(VRingPackedDesc);
+i = 0;
+vring_packed_desc_read(vdev, , cache, i);
+/* Make sure we see all the fields*/
+smp_rmb();
+}
+
+/* Collect all the descriptors */
+while (1) {
+bool map_ok;
+
+if (desc.flags & VRING_DESC_F_WRITE) {
+map_ok = virtqueue_map_desc(vdev, _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, _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, , cache, i);
+} else {
+break;
+}
+}
+
+/* Now copy what we have collected and mapped */
+elem = virtqueue_alloc_element(sz, out_num, in_num);
+elem->index = id;
+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 == _desc_cache) ?
+ 1 : out_num + in_num;
I think you cannot rely on out_num and in_num to deduce the number of
descriptors.
Indeed, in
