[Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring
From: Wei Xu
Signed-off-by: Wei Xu
---
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 {
+
Re: [Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring
On Wed, Jun 06, 2018 at 11:41:18AM +0800, Jason Wang wrote: > > > On 2018年06月06日 11:38, Wei Xu wrote: > >>>+ > >>>+head = vq->last_avail_idx; > >>>+i = head; > >>>+ > >>>+caches = vring_get_region_caches(vq); > >>>+cache = &caches->desc; > >>>+vring_packed_desc_read(vdev, &desc, cache, i); > >>I think we'd better find a way to avoid reading descriptor twice. > >Do you mean here and the read for empty check? > > > >Wei > > > > Yes. OK, will figure it out. > > Thanks > >
Re: [Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring
On 2018年06月06日 03:08, w...@redhat.com wrote:
From: Wei Xu
Signed-off-by: Wei Xu
---
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;
+}
Instead of depending on the barriers inside
virtio_queue_packed_empty_rcu(). I think it's better to keep a smp_rmb()
here with comments.
+
+/* 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 */
+}
This part could be removed.
+
+head = vq->last_avail_idx;
+i = head;
+
+caches = vring_get_region_caches(vq);
+cache = &caches->desc;
+vring_packed_desc_read(vdev, &desc, cache, i);
I think we'd better find a way to avoid reading descriptor twice.
Thanks
+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()
Re: [Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring
On Wed, Jun 06, 2018 at 11:29:54AM +0800, Jason Wang wrote:
>
>
> On 2018年06月06日 03:08, w...@redhat.com wrote:
> >From: Wei Xu
> >
> >Signed-off-by: Wei Xu
> >---
> > 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;
> >+}
>
> Instead of depending on the barriers inside virtio_queue_packed_empty_rcu().
> I think it's better to keep a smp_rmb() here with comments.
OK.
>
> >+
> >+/* 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 */
> >+}
>
> This part could be removed.
My bad, thanks.
>
> >+
> >+head = vq->last_avail_idx;
> >+i = head;
> >+
> >+caches = vring_get_region_caches(vq);
> >+cache = &caches->desc;
> >+vring_packed_desc_read(vdev, &desc, cache, i);
>
> I think we'd better find a way to avoid reading descriptor twice.
Do you mean here and the read for empty check?
Wei
>
> Thanks
>
> >+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++)
Re: [Qemu-devel] [RFC v2 5/8] virtio: queue pop for packed ring
On 2018年06月06日 11:38, Wei Xu wrote: + +head = vq->last_avail_idx; +i = head; + +caches = vring_get_region_caches(vq); +cache = &caches->desc; +vring_packed_desc_read(vdev, &desc, cache, i); I think we'd better find a way to avoid reading descriptor twice. Do you mean here and the read for empty check? Wei Yes. Thanks
