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Message-Id: <20230602092206.50108-8-xuanzhuo@linux.alibaba.com>
Date: Fri, 2 Jun 2023 17:22:03 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: virtualization@...ts.linux-foundation.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
netdev@...r.kernel.org,
bpf@...r.kernel.org
Subject: [PATCH vhost v10 07/10] virtio_ring: introduce helpers for premapped
This patch introduces three helpers for premapped mode.
* virtqueue_get_buf_premapped
* virtqueue_detach_unused_buf_premapped
The above helpers work like the non-premapped funcs. But a cursor is
passed.
virtqueue_detach is used to get the dma info of the last buf by
cursor.
Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 83 ++++++++++++++++++++++++++++++++++++
include/linux/virtio.h | 10 +++++
2 files changed, 93 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index cbc22daae7e1..6771b9661798 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2555,6 +2555,66 @@ 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_get_buf_premapped - get the next used buffer
+ * @_vq: the struct virtqueue we're talking about.
+ * @len: the length written into the buffer
+ * @ctx: extra context for the token
+ * @cursor: detach cursor
+ *
+ * If the device wrote data into the buffer, @len will be set to the
+ * amount written. This means you don't need to clear the buffer
+ * beforehand to ensure there's no data leakage in the case of short
+ * writes.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ *
+ * This is used for the premapped vq. The cursor is passed by the dirver, that
+ * is used for virtqueue_detach. That will be initialized by virtio core
+ * internally.
+ *
+ * Returns NULL if there are no used buffers, or the "data" token
+ * handed to virtqueue_add_*().
+ */
+void *virtqueue_get_buf_premapped(struct virtqueue *_vq, unsigned int *len,
+ void **ctx,
+ struct virtqueue_detach_cursor *cursor)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx, cursor) :
+ virtqueue_get_buf_ctx_split(_vq, len, ctx, cursor);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_buf_premapped);
+
+/**
+ * virtqueue_detach - get the dma info of last buf
+ * @_vq: the struct virtqueue we're talking about.
+ * @cursor: detach cursor
+ * @addr: the dma address
+ * @len: the length of the dma address
+ * @dir: the direction of the dma address
+ *
+ * This is used for the premapped vq. The cursor is initialized by
+ * virtqueue_get_buf_premapped or virtqueue_detach_unused_buf_premapped.
+ *
+ * Returns:
+ * -EAGAIN: there are more dma info, this function should be called more.
+ * -EINVAL: the process is done, should not call this function
+ * 0: no more dma info
+ */
+int virtqueue_detach(struct virtqueue *_vq, struct virtqueue_detach_cursor *cursor,
+ dma_addr_t *addr, u32 *len, enum dma_data_direction *dir)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ return vq->packed_ring ? virtqueue_detach_packed(_vq, cursor, addr, len, dir) :
+ virtqueue_detach_split(_vq, cursor, addr, len, dir);
+}
+EXPORT_SYMBOL_GPL(virtqueue_detach);
+
/**
* virtqueue_disable_cb - disable callbacks
* @_vq: the struct virtqueue we're talking about.
@@ -2682,6 +2742,29 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
}
EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
+/**
+ * virtqueue_detach_unused_buf_premapped - detach first unused buffer
+ * @_vq: the struct virtqueue we're talking about.
+ * @cursor: detach cursor
+ *
+ * This is used for the premapped vq. The cursor is passed by the dirver, that
+ * is used for virtqueue_detach. That will be initialized by virtio core
+ * internally.
+ *
+ * Returns NULL or the "data" token handed to virtqueue_add_*().
+ * This is not valid on an active queue; it is useful for device
+ * shutdown or the reset queue.
+ */
+void *virtqueue_detach_unused_buf_premapped(struct virtqueue *_vq,
+ struct virtqueue_detach_cursor *cursor)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq, cursor) :
+ virtqueue_detach_unused_buf_split(_vq, cursor);
+}
+EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf_premapped);
+
static inline bool more_used(const struct vring_virtqueue *vq)
{
return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 7f137c7a9034..0a11c5b32fe5 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -3,6 +3,7 @@
#define _LINUX_VIRTIO_H
/* Everything a virtio driver needs to work with any particular virtio
* implementation. */
+#include <linux/dma-mapping.h>
#include <linux/types.h>
#include <linux/scatterlist.h>
#include <linux/spinlock.h>
@@ -88,6 +89,10 @@ 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_get_buf_premapped(struct virtqueue *_vq, unsigned int *len,
+ void **ctx,
+ struct virtqueue_detach_cursor *cursor);
+
void virtqueue_disable_cb(struct virtqueue *vq);
bool virtqueue_enable_cb(struct virtqueue *vq);
@@ -101,6 +106,8 @@ bool virtqueue_poll(struct virtqueue *vq, unsigned);
bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
void *virtqueue_detach_unused_buf(struct virtqueue *vq);
+void *virtqueue_detach_unused_buf_premapped(struct virtqueue *_vq,
+ struct virtqueue_detach_cursor *cursor);
unsigned int virtqueue_get_vring_size(const struct virtqueue *vq);
@@ -114,6 +121,9 @@ dma_addr_t virtqueue_get_used_addr(const struct virtqueue *vq);
int virtqueue_resize(struct virtqueue *vq, u32 num,
void (*recycle)(struct virtqueue *vq, void *buf));
+int virtqueue_detach(struct virtqueue *_vq, struct virtqueue_detach_cursor *cursor,
+ dma_addr_t *addr, u32 *len, enum dma_data_direction *dir);
+
/**
* struct virtio_device - representation of a device using virtio
* @index: unique position on the virtio bus
--
2.32.0.3.g01195cf9f
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