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Message-ID: <1490820507-8005-4-git-send-email-mst@redhat.com>
Date: Wed, 29 Mar 2017 23:48:53 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: John Fastabend <john.fastabend@...il.com>,
Jason Wang <jasowang@...hat.com>,
virtualization@...ts.linux-foundation.org
Subject: [PATCH 3/6] virtio: allow extra context per descriptor
Allow extra context per descriptor. To avoid slow down for data path,
this disables use of indirect descriptors for this vq.
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
drivers/virtio/virtio_ring.c | 70 ++++++++++++++++++++++++++++++++++++--------
include/linux/virtio.h | 9 ++++++
2 files changed, 66 insertions(+), 13 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index b23b5fa..5e1b548 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -263,6 +263,7 @@ static inline int virtqueue_add(struct virtqueue *_vq,
unsigned int out_sgs,
unsigned int in_sgs,
void *data,
+ void *ctx,
gfp_t gfp)
{
struct vring_virtqueue *vq = to_vvq(_vq);
@@ -275,6 +276,7 @@ static inline int virtqueue_add(struct virtqueue *_vq,
START_USE(vq);
BUG_ON(data == NULL);
+ BUG_ON(ctx && vq->indirect);
if (unlikely(vq->broken)) {
END_USE(vq);
@@ -389,6 +391,8 @@ static inline int virtqueue_add(struct virtqueue *_vq,
vq->desc_state[head].data = data;
if (indirect)
vq->desc_state[head].indir_desc = desc;
+ if (ctx)
+ vq->desc_state[head].indir_desc = ctx;
/* Put entry in available array (but don't update avail->idx until they
* do sync). */
@@ -461,7 +465,8 @@ int virtqueue_add_sgs(struct virtqueue *_vq,
for (sg = sgs[i]; sg; sg = sg_next(sg))
total_sg++;
}
- return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs, data, gfp);
+ return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs,
+ data, NULL, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
@@ -483,7 +488,7 @@ int virtqueue_add_outbuf(struct virtqueue *vq,
void *data,
gfp_t gfp)
{
- return virtqueue_add(vq, &sg, num, 1, 0, data, gfp);
+ return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
@@ -505,11 +510,35 @@ int virtqueue_add_inbuf(struct virtqueue *vq,
void *data,
gfp_t gfp)
{
- return virtqueue_add(vq, &sg, num, 0, 1, data, gfp);
+ return virtqueue_add(vq, &sg, num, 0, 1, data, NULL, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);
/**
+ * virtqueue_add_inbuf_ctx - expose input buffers to other end
+ * @vq: the struct virtqueue we're talking about.
+ * @sg: scatterlist (must be well-formed and terminated!)
+ * @num: the number of entries in @sg writable by other side
+ * @data: the token identifying the buffer.
+ * @ctx: extra context for the token
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
+ struct scatterlist *sg, unsigned int num,
+ void *data,
+ void *ctx,
+ gfp_t gfp)
+{
+ return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
+
+/**
* virtqueue_kick_prepare - first half of split virtqueue_kick call.
* @vq: the struct virtqueue
*
@@ -598,7 +627,8 @@ bool virtqueue_kick(struct virtqueue *vq)
}
EXPORT_SYMBOL_GPL(virtqueue_kick);
-static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
+static void detach_buf(struct vring_virtqueue *vq, unsigned int head,
+ void **ctx)
{
unsigned int i, j;
__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
@@ -622,10 +652,15 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
/* Plus final descriptor */
vq->vq.num_free++;
- /* Free the indirect table, if any, now that it's unmapped. */
- if (vq->desc_state[head].indir_desc) {
+ if (vq->indirect) {
struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
- u32 len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
+ u32 len;
+
+ /* Free the indirect table, if any, now that it's unmapped. */
+ if (!indir_desc)
+ return;
+
+ len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
BUG_ON(!(vq->vring.desc[head].flags &
cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
@@ -634,8 +669,10 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
for (j = 0; j < len / sizeof(struct vring_desc); j++)
vring_unmap_one(vq, &indir_desc[j]);
- kfree(vq->desc_state[head].indir_desc);
+ kfree(indir_desc);
vq->desc_state[head].indir_desc = NULL;
+ } else if (ctx) {
+ *ctx = vq->desc_state[head].indir_desc;
}
}
@@ -660,7 +697,8 @@ static inline bool more_used(const struct vring_virtqueue *vq)
* Returns NULL if there are no used buffers, or the "data" token
* handed to virtqueue_add_*().
*/
-void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
+void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
+ void **ctx)
{
struct vring_virtqueue *vq = to_vvq(_vq);
void *ret;
@@ -698,7 +736,7 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
/* detach_buf clears data, so grab it now. */
ret = vq->desc_state[i].data;
- detach_buf(vq, i);
+ detach_buf(vq, i, ctx);
vq->last_used_idx++;
/* If we expect an interrupt for the next entry, tell host
* by writing event index and flush out the write before
@@ -715,8 +753,13 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
END_USE(vq);
return ret;
}
-EXPORT_SYMBOL_GPL(virtqueue_get_buf);
+EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
+void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
+{
+ return virtqueue_get_buf_ctx(_vq, len, NULL);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_buf);
/**
* virtqueue_disable_cb - disable callbacks
* @vq: the struct virtqueue we're talking about.
@@ -878,7 +921,7 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
continue;
/* detach_buf clears data, so grab it now. */
buf = vq->desc_state[i].data;
- detach_buf(vq, i);
+ detach_buf(vq, i, NULL);
vq->avail_idx_shadow--;
vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
END_USE(vq);
@@ -951,7 +994,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
vq->last_add_time_valid = false;
#endif
- vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
+ vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
+ !context;
vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
/* No callback? Tell other side not to bother us. */
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 04b0d3f9..193fea9 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -44,6 +44,12 @@ int virtqueue_add_inbuf(struct virtqueue *vq,
void *data,
gfp_t gfp);
+int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
+ struct scatterlist sg[], unsigned int num,
+ void *data,
+ void *ctx,
+ gfp_t gfp);
+
int virtqueue_add_sgs(struct virtqueue *vq,
struct scatterlist *sgs[],
unsigned int out_sgs,
@@ -59,6 +65,9 @@ bool virtqueue_notify(struct virtqueue *vq);
void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
+void *virtqueue_get_buf_ctx(struct virtqueue *vq, unsigned int *len,
+ void **ctx);
+
void virtqueue_disable_cb(struct virtqueue *vq);
bool virtqueue_enable_cb(struct virtqueue *vq);
--
MST
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