On Wed, Apr 11, 2018 at 11:03:24AM +0800, Jason Wang wrote:
>
>
> On 2018年04月04日 20:54, w...@redhat.com wrote:
> >From: Wei Xu <w...@redhat.com>
> >
> >mostly as same as 1.0, copy it separately for
> >prototype, need a refactoring.
> >
> >Signed-off-by: Wei Xu <w...@redhat.com>
> >---
> > hw/virtio/virtio.c | 142
> > +++++++++++++++++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 139 insertions(+), 3 deletions(-)
> >
> >diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >index def07c6..cf726f3 100644
> >--- a/hw/virtio/virtio.c
> >+++ b/hw/virtio/virtio.c
> >@@ -836,9 +836,9 @@ static int virtqueue_read_next_desc(VirtIODevice *vdev,
> >VRingDesc *desc,
> > return VIRTQUEUE_READ_DESC_MORE;
> > }
> >-void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
> >- unsigned int *out_bytes,
> >- unsigned max_in_bytes, unsigned
> >max_out_bytes)
> >+static void virtqueue_get_avail_bytes_split(VirtQueue *vq,
> >+ unsigned int *in_bytes, unsigned int *out_bytes,
> >+ unsigned max_in_bytes, unsigned max_out_bytes)
> > {
> > VirtIODevice *vdev = vq->vdev;
> > unsigned int max, idx;
> >@@ -961,6 +961,142 @@ err:
> > goto done;
> > }
> >+static void virtqueue_get_avail_bytes_packed(VirtQueue *vq,
> >+ unsigned int *in_bytes, unsigned int *out_bytes,
> >+ unsigned max_in_bytes, unsigned max_out_bytes)
> >+{
> >+ VirtIODevice *vdev = vq->vdev;
> >+ unsigned int max, idx;
> >+ unsigned int total_bufs, in_total, out_total;
> >+ MemoryRegionCache *desc_cache;
> >+ VRingMemoryRegionCaches *caches;
> >+ MemoryRegionCache indirect_desc_cache = MEMORY_REGION_CACHE_INVALID;
> >+ int64_t len = 0;
> >+ VRingDescPacked desc;
> >+
> >+ if (unlikely(!vq->packed.desc)) {
> >+ if (in_bytes) {
> >+ *in_bytes = 0;
> >+ }
> >+ if (out_bytes) {
> >+ *out_bytes = 0;
> >+ }
> >+ return;
> >+ }
> >+
> >+ rcu_read_lock();
> >+ idx = vq->last_avail_idx;
> >+ total_bufs = in_total = out_total = 0;
> >+
> >+ max = vq->packed.num;
> >+ caches = vring_get_region_caches(vq);
> >+ if (caches->desc.len < max * sizeof(VRingDescPacked)) {
> >+ virtio_error(vdev, "Cannot map descriptor ring");
> >+ goto err;
> >+ }
> >+
> >+ desc_cache = &caches->desc;
> >+ vring_desc_read_packed(vdev, &desc, desc_cache, idx);
> >+ while (is_desc_avail(&desc)) {
> >+ unsigned int num_bufs;
> >+ unsigned int i;
> >+
> >+ num_bufs = total_bufs;
> >+
> >+ if (desc.flags & VRING_DESC_F_INDIRECT) {
> >+ if (desc.len % sizeof(VRingDescPacked)) {
> >+ virtio_error(vdev, "Invalid size for indirect buffer
> >table");
> >+ goto err;
> >+ }
> >+
> >+ /* If we've got too many, that implies a descriptor loop. */
> >+ if (num_bufs >= max) {
> >+ virtio_error(vdev, "Looped descriptor");
> >+ goto err;
> >+ }
> >+
> >+ /* loop over the indirect descriptor table */
> >+ len = address_space_cache_init(&indirect_desc_cache,
> >+ vdev->dma_as,
> >+ desc.addr, desc.len, false);
> >+ desc_cache = &indirect_desc_cache;
> >+ if (len < desc.len) {
> >+ virtio_error(vdev, "Cannot map indirect buffer");
> >+ goto err;
> >+ }
> >+
> >+ max = desc.len / sizeof(VRingDescPacked);
> >+ num_bufs = i = 0;
> >+ vring_desc_read_packed(vdev, &desc, desc_cache, i);
> >+ }
> >+
> >+ do {
> >+ /* If we've got too many, that implies a descriptor loop. */
> >+ if (++num_bufs > max) {
> >+ virtio_error(vdev, "Looped descriptor");
> >+ goto err;
> >+ }
> >+
> >+ if (desc.flags & VRING_DESC_F_WRITE) {
> >+ in_total += desc.len;
> >+ } else {
> >+ out_total += desc.len;
> >+ }
> >+ if (in_total >= max_in_bytes && out_total >= max_out_bytes) {
> >+ goto done;
> >+ }
> >+
> >+ if (desc_cache == &indirect_desc_cache) {
> >+ vring_desc_read_packed(vdev, &desc, desc_cache,
> >+ ++i % vq->packed.num);
> >+ } else {
> >+ vring_desc_read_packed(vdev, &desc, desc_cache,
> >+ ++idx % vq->packed.num);
> >+ }
>
> Need to make sure desc.flags was read before other fields, otherwise we may
> get stale address.
OK, need a barrier here, thanks.
Wei
>
> Thanks
>
> >+ } while (desc.flags & VRING_DESC_F_NEXT);
> >+
> >+ if (desc_cache == &indirect_desc_cache) {
> >+ address_space_cache_destroy(&indirect_desc_cache);
> >+ total_bufs++;
> >+ /* We missed one step on for indirect desc */
> >+ idx++;
> >+ } else {
> >+ total_bufs = num_bufs;
> >+ }
> >+
> >+ desc_cache = &caches->desc;
> >+ vring_desc_read_packed(vdev, &desc, desc_cache, idx %
> >vq->packed.num);
> >+ }
> >+
> >+done:
> >+ address_space_cache_destroy(&indirect_desc_cache);
> >+ if (in_bytes) {
> >+ *in_bytes = in_total;
> >+ }
> >+ if (out_bytes) {
> >+ *out_bytes = out_total;
> >+ }
> >+ rcu_read_unlock();
> >+ return;
> >+
> >+err:
> >+ in_total = out_total = 0;
> >+ goto done;
> >+}
> >+
> >+void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
> >+ unsigned int *out_bytes,
> >+ unsigned max_in_bytes, unsigned
> >max_out_bytes)
> >+{
> >+ if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
> >+ virtqueue_get_avail_bytes_packed(vq, in_bytes, out_bytes,
> >+ max_in_bytes, max_out_bytes);
> >+ } else {
> >+ virtqueue_get_avail_bytes_split(vq, in_bytes, out_bytes,
> >+ max_in_bytes, max_out_bytes);
> >+ }
> >+}
> >+
> > int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
> > unsigned int out_bytes)
> > {
>
>
