Re: [PATCH RFC v8 05/11] vhost: format-independent API for used buffers
On Thu, Jun 11, 2020 at 1:34 PM Michael S. Tsirkin wrote:
>
> Add a new API that doesn't assume used ring, heads, etc.
> For now, we keep the old APIs around to make it easier
> to convert drivers.
>
> Signed-off-by: Michael S. Tsirkin
> ---
> drivers/vhost/vhost.c | 73 +--
> drivers/vhost/vhost.h | 17 +-
> 2 files changed, 79 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index c38605b01080..03e6bca02288 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -2335,13 +2335,12 @@ static void unfetch_descs(struct vhost_virtqueue *vq)
> * 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_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)
> + * This function returns a value > 0 if a descriptor was found, or 0 if none
> were found.
> + * A negative code is returned on error. */
> +int vhost_get_avail_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf,
> + struct iovec iov[], unsigned int iov_size,
> + unsigned int *out_num, unsigned int *in_num,
> + struct vhost_log *log, unsigned int *log_num)
> {
> int ret = fetch_descs(vq);
> int i;
> @@ -2354,6 +2353,8 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
> *out_num = *in_num = 0;
> if (unlikely(log))
> *log_num = 0;
> + buf->in_len = buf->out_len = 0;
> + buf->descs = 0;
>
> for (i = vq->first_desc; i < vq->ndescs; ++i) {
> unsigned iov_count = *in_num + *out_num;
> @@ -2383,6 +2384,7 @@ int (struct vhost_virtqueue *vq,
> /* If this is an input descriptor,
> * increment that count. */
> *in_num += ret;
> + buf->in_len += desc->len;
> if (unlikely(log && ret)) {
> log[*log_num].addr = desc->addr;
> log[*log_num].len = desc->len;
> @@ -2398,9 +2400,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
> goto err;
> }
> *out_num += ret;
> + buf->out_len += desc->len;
> }
>
> - ret = desc->id;
> + buf->id = desc->id;
> + ++buf->descs;
>
> if (!(desc->flags & VRING_DESC_F_NEXT))
> break;
> @@ -2408,12 +2412,41 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
>
> vq->first_desc = i + 1;
>
> - return ret;
> + return 1;
>
> err:
> unfetch_descs(vq);
>
> - return ret ? ret : vq->num;
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vhost_get_avail_buf);
> +
> +/* Reverse the effect of vhost_get_avail_buf. Useful for error handling. */
> +void vhost_discard_avail_bufs(struct vhost_virtqueue *vq,
> + struct vhost_buf *buf, unsigned count)
> +{
> + vhost_discard_vq_desc(vq, count);
> +}
> +EXPORT_SYMBOL_GPL(vhost_discard_avail_bufs);
> +
> +/* 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_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 vhost_buf buf;
> + int ret = vhost_get_avail_buf(vq, ,
> + iov, iov_size, out_num, in_num,
> + log, log_num);
> +
> + if (likely(ret > 0))
> + return buf->id;
This should be buf.id, isn't it?
> + if (likely(!ret))
> + return vq->num;
> + return ret;
> }
> EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
>
> @@ -2507,6 +2540,26 @@ int vhost_add_used(struct vhost_virtqueue *vq,
> unsigned int head, int len)
> }
> EXPORT_SYMBOL_GPL(vhost_add_used);
>
> +int vhost_put_used_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf)
> +{
> + return vhost_add_used(vq, buf->id, buf->in_len);
> +}
> +EXPORT_SYMBOL_GPL(vhost_put_used_buf);
> +
> +int vhost_put_used_n_bufs(struct vhost_virtqueue *vq,
> + struct vhost_buf *bufs, unsigned
[PATCH RFC v8 05/11] vhost: format-independent API for used buffers
Add a new API that doesn't assume used ring, heads, etc.
For now, we keep the old APIs around to make it easier
to convert drivers.
Signed-off-by: Michael S. Tsirkin
---
drivers/vhost/vhost.c | 73 +--
drivers/vhost/vhost.h | 17 +-
2 files changed, 79 insertions(+), 11 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index c38605b01080..03e6bca02288 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2335,13 +2335,12 @@ static void unfetch_descs(struct vhost_virtqueue *vq)
* 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_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)
+ * This function returns a value > 0 if a descriptor was found, or 0 if none
were found.
+ * A negative code is returned on error. */
+int vhost_get_avail_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num)
{
int ret = fetch_descs(vq);
int i;
@@ -2354,6 +2353,8 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
*out_num = *in_num = 0;
if (unlikely(log))
*log_num = 0;
+ buf->in_len = buf->out_len = 0;
+ buf->descs = 0;
for (i = vq->first_desc; i < vq->ndescs; ++i) {
unsigned iov_count = *in_num + *out_num;
@@ -2383,6 +2384,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
/* If this is an input descriptor,
* increment that count. */
*in_num += ret;
+ buf->in_len += desc->len;
if (unlikely(log && ret)) {
log[*log_num].addr = desc->addr;
log[*log_num].len = desc->len;
@@ -2398,9 +2400,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
goto err;
}
*out_num += ret;
+ buf->out_len += desc->len;
}
- ret = desc->id;
+ buf->id = desc->id;
+ ++buf->descs;
if (!(desc->flags & VRING_DESC_F_NEXT))
break;
@@ -2408,12 +2412,41 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
vq->first_desc = i + 1;
- return ret;
+ return 1;
err:
unfetch_descs(vq);
- return ret ? ret : vq->num;
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vhost_get_avail_buf);
+
+/* Reverse the effect of vhost_get_avail_buf. Useful for error handling. */
+void vhost_discard_avail_bufs(struct vhost_virtqueue *vq,
+ struct vhost_buf *buf, unsigned count)
+{
+ vhost_discard_vq_desc(vq, count);
+}
+EXPORT_SYMBOL_GPL(vhost_discard_avail_bufs);
+
+/* 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_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 vhost_buf buf;
+ int ret = vhost_get_avail_buf(vq, ,
+ iov, iov_size, out_num, in_num,
+ log, log_num);
+
+ if (likely(ret > 0))
+ return buf->id;
+ if (likely(!ret))
+ return vq->num;
+ return ret;
}
EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
@@ -2507,6 +2540,26 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned
int head, int len)
}
EXPORT_SYMBOL_GPL(vhost_add_used);
+int vhost_put_used_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf)
+{
+ return vhost_add_used(vq, buf->id, buf->in_len);
+}
+EXPORT_SYMBOL_GPL(vhost_put_used_buf);
+
+int vhost_put_used_n_bufs(struct vhost_virtqueue *vq,
+ struct vhost_buf *bufs, unsigned count)
+{
+ unsigned i;
+
+ for (i = 0; i < count; ++i) {
+ vq->heads[i].id = cpu_to_vhost32(vq, bufs[i].id);
+ vq->heads[i].len = cpu_to_vhost32(vq, bufs[i].in_len);
+ }
+
+ return vhost_add_used_n(vq, vq->heads, count);
+}
