Re: [Qemu-devel] [RFC v2 2/8] virtio: memory cache for packed ring

[Wei Xu]

On Wed, Jun 06, 2018 at 10:53:07AM +0800, Jason Wang wrote:
> 
> 
> On 2018年06月06日 03:07, address@hidden wrote:
> >From: Wei Xu <address@hidden>
> >
> >Mostly reuse memory cache with 1.0 except for the offset calculation.
> >
> >Signed-off-by: Wei Xu <address@hidden>
> >---
> >  hw/virtio/virtio.c | 29 ++++++++++++++++++++---------
> >  1 file changed, 20 insertions(+), 9 deletions(-)
> >
> >diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >index e192a9a..f6c0689 100644
> >--- a/hw/virtio/virtio.c
> >+++ b/hw/virtio/virtio.c
> >@@ -150,11 +150,8 @@ static void virtio_init_region_cache(VirtIODevice 
> >*vdev, int n)
> >      VRingMemoryRegionCaches *old = vq->vring.caches;
> >      VRingMemoryRegionCaches *new;
> >      hwaddr addr, size;
> >-    int event_size;
> >      int64_t len;
> >-    event_size = virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX) 
> >? 2 : 0;
> >-
> >      addr = vq->vring.desc;
> >      if (!addr) {
> >          return;
> >@@ -168,7 +165,7 @@ static void virtio_init_region_cache(VirtIODevice *vdev, 
> >int n)
> >          goto err_desc;
> >      }
> >-    size = virtio_queue_get_used_size(vdev, n) + event_size;
> >+    size = virtio_queue_get_used_size(vdev, n);
> >      len = address_space_cache_init(&new->used, vdev->dma_as,
> >                                     vq->vring.used, size, true);
> >      if (len < size) {
> >@@ -176,7 +173,7 @@ static void virtio_init_region_cache(VirtIODevice *vdev, 
> >int n)
> >          goto err_used;
> >      }
> >-    size = virtio_queue_get_avail_size(vdev, n) + event_size;
> >+    size = virtio_queue_get_avail_size(vdev, n);
> >      len = address_space_cache_init(&new->avail, vdev->dma_as,
> >                                     vq->vring.avail, size, false);
> >      if (len < size) {
> >@@ -2320,14 +2317,28 @@ hwaddr virtio_queue_get_desc_size(VirtIODevice 
> >*vdev, int n)
> >  hwaddr virtio_queue_get_avail_size(VirtIODevice *vdev, int n)
> 
> I would rather rename this to virtio_queue_get_driver_size().

Would this confuse 1.0 if it is shared by both? Otherwise I will take it to 
next version, thanks.

Wei

> 
> >  {
> >-    return offsetof(VRingAvail, ring) +
> >-        sizeof(uint16_t) * vdev->vq[n].vring.num;
> >+    int s;
> >+
> >+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> >+        return sizeof(struct VRingPackedDescEvent);
> >+    } else {
> >+        s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> >+        return offsetof(VRingAvail, ring) +
> >+            sizeof(uint16_t) * vdev->vq[n].vring.num + s;
> >+    }
> >  }
> >  hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
> 
> virtio_queue_get_device_size().
> 
> Thanks
> 
> >  {
> >-    return offsetof(VRingUsed, ring) +
> >-        sizeof(VRingUsedElem) * vdev->vq[n].vring.num;
> >+    int s;
> >+
> >+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> >+        return sizeof(struct VRingPackedDescEvent);
> >+    } else {
> >+        s = virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> >+        return offsetof(VRingUsed, ring) +
> >+            sizeof(VRingUsedElem) * vdev->vq[n].vring.num + s;
> >+    }
> >  }
> >  uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>