Prepare for moving virtio ring code out to a separate
file by isolating vring related functions. The function
vring_add_used_user() and vring_avail_desc_user() that
are handling virtio rings from user space are prepared
to be moved out.
Signed-off-by: Sjur Brændeland <sjur.brandel...@stericsson.com>
---
drivers/vhost/vhost.c | 119 ++++++++++++++++++++++++++++--------------------
1 files changed, 69 insertions(+), 50 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 0a676f1..5e91048 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1100,7 +1100,7 @@ static int translate_desc(struct vhost_dev *dev, u64
addr, u32 len,
/* Each buffer in the virtqueues is actually a chain of descriptors. This
* function returns the next descriptor in the chain,
* or -1U if we're at the end. */
-static unsigned next_desc(struct vring_desc *desc)
+unsigned vring_next_desc(struct vring_desc *desc)
{
unsigned int next;
@@ -1202,46 +1202,29 @@ static int get_indirect(struct vhost_dev *dev, struct
vhost_virtqueue *vq,
}
*out_num += ret;
}
- } while ((i = next_desc(&desc)) != -1);
+ } while ((i = vring_next_desc(&desc)) != -1);
return 0;
}
-/* This looks in the virtqueue and for the first available buffer, and converts
- * it to an iovec for convenient access. Since descriptors consist of some
- * number of output then some number of input descriptors, it's actually two
- * iovecs, but we pack them into one and note how many of each there were.
- *
- * This function returns the descriptor number found, or vq->num (which is
- * never a valid descriptor number) if none was found. A negative code is
- * returned on error. */
-int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
- struct iovec iov[], unsigned int iov_size,
- unsigned int *out_num, unsigned int *in_num,
- struct vhost_log *log, unsigned int *log_num)
+static int vring_avail_desc_user(struct vring_host *vh)
{
- struct vring_desc desc;
- unsigned int i, head, found = 0;
+ int head;
u16 last_avail_idx;
- int ret;
/* Check it isn't doing very strange things with descriptor numbers. */
- last_avail_idx = vq->hst.last_avail_idx;
- if (unlikely(__get_user(vq->hst.avail_idx, &vq->hst.vr.avail->idx))) {
- vq_err(vq, "Failed to access avail idx at %p\n",
- &vq->hst.vr.avail->idx);
+ last_avail_idx = vh->last_avail_idx;
+ if (unlikely(__get_user(vh->avail_idx, &vh->vr.avail->idx))) {
+ pr_debug("Failed to access avail idx at %p\n",
+ &vh->vr.avail->idx);
return -EFAULT;
}
- if (unlikely((u16)(vq->hst.avail_idx -
- last_avail_idx) > vq->hst.vr.num)) {
- vq_err(vq, "Guest moved used index from %u to %u",
- last_avail_idx, vq->hst.avail_idx);
+ if (unlikely((u16)(vh->avail_idx - last_avail_idx) > vh->vr.num))
return -EFAULT;
- }
/* If there's nothing new since last we looked, return invalid. */
- if (vq->hst.avail_idx == last_avail_idx)
- return vq->hst.vr.num;
+ if (vh->avail_idx == last_avail_idx)
+ return vh->vr.num;
/* Only get avail ring entries after they have been exposed by guest. */
smp_rmb();
@@ -1249,22 +1232,46 @@ int vhost_get_vq_desc(struct vhost_dev *dev, struct
vhost_virtqueue *vq,
/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
if (unlikely(__get_user(head,
- &vq->hst.vr.avail->ring[last_avail_idx %
- vq->hst.vr.num]))) {
- vq_err(vq, "Failed to read head: idx %d address %p\n",
- last_avail_idx,
- &vq->hst.vr.avail->ring[last_avail_idx %
- vq->hst.vr.num]);
+ &vh->vr.avail->ring[last_avail_idx %
+ vh->vr.num]))) {
+ pr_debug("Failed to read head: idx %d address %p\n",
+ last_avail_idx,
+ &vh->vr.avail->ring[last_avail_idx %
+ vh->vr.num]);
return -EFAULT;
}
/* If their number is silly, that's an error. */
- if (unlikely(head >= vq->hst.vr.num)) {
- vq_err(vq, "Guest says index %u > %u is available",
- head, vq->hst.vr.num);
+ if (unlikely(head >= vh->vr.num)) {
+ pr_debug("Guest says index %u > %u is available",
+ head, vh->vr.num);
return -EINVAL;
}
+ return head;
+}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access. Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found. A negative code is
+ * returned on error. */
+int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num)
+{
+ struct vring_desc desc;
+ unsigned int i, head, found = 0;
+ int ret;
+
+ head = vring_avail_desc_user(&vq->hst);
+ if (head < 0)
+ vq_err(vq, "virtqueue_next_avail failed\n");
+
/* When we start there are none of either input nor output. */
*out_num = *in_num = 0;
if (unlikely(log))
@@ -1328,7 +1335,7 @@ int vhost_get_vq_desc(struct vhost_dev *dev, struct
vhost_virtqueue *vq,
}
*out_num += ret;
}
- } while ((i = next_desc(&desc)) != -1);
+ } while ((i = vring_next_desc(&desc)) != -1);
/* On success, increment avail index. */
vq->hst.last_avail_idx++;
@@ -1345,29 +1352,41 @@ void vhost_discard_vq_desc(struct vhost_virtqueue *vq,
int n)
vq->hst.last_avail_idx -= n;
}
-/* After we've used one of their buffers, we tell them about it. We'll then
- * want to notify the guest, using eventfd. */
-int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
+struct vring_used_elem *vring_add_used_user(struct vring_host *vh,
+ unsigned int head, int len)
{
- struct vring_used_elem __user *used;
+ struct vring_used_elem *used;
/* The virtqueue contains a ring of used buffers. Get a pointer to the
* next entry in that used ring. */
- used = &vq->hst.vr.used->ring[vq->hst.last_used_idx % vq->hst.vr.num];
+ used = &vh->vr.used->ring[vh->last_used_idx % vh->vr.num];
if (__put_user(head, &used->id)) {
- vq_err(vq, "Failed to write used id");
- return -EFAULT;
+ pr_debug("Failed to write used id");
+ return NULL;
}
if (__put_user(len, &used->len)) {
- vq_err(vq, "Failed to write used len");
- return -EFAULT;
+ pr_debug("Failed to write used len");
+ return NULL;
}
/* Make sure buffer is written before we update index. */
smp_wmb();
- if (__put_user(vq->hst.last_used_idx + 1, &vq->hst.vr.used->idx)) {
- vq_err(vq, "Failed to increment used idx");
- return -EFAULT;
+ if (__put_user(vh->last_used_idx + 1, &vh->vr.used->idx)) {
+ pr_debug("Failed to increment used idx");
+ return NULL;
}
+ vh->last_used_idx++;
+ return used;
+}
+
+/* After we've used one of their buffers, we tell them about it. We'll then
+ * want to notify the guest, using eventfd. */
+int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
+{
+ struct vring_used_elem *used;
+ used = vring_add_used_user(&vq->hst, head, len);
+ if (!used)
+ vq_err(vq, "Failed to write to vring");
+
if (unlikely(vq->log_used)) {
/* Make sure data is seen before log. */
smp_wmb();
--
1.7.5.4
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