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virtio_ring: introduce dma map api for virtqueue

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Added virtqueue_dma_map_api* to map DMA addresses for virtual memory in
advance. The purpose is to keep memory mapped across multiple add/get
buf operations.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230810123057.43407-11-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Xuan Zhuo 2023-08-10 20:30:55 +08:00 committed by Michael S. Tsirkin
parent ba3e0c47c0
commit b6253b4e21
2 changed files with 77 additions and 0 deletions
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69
drivers/virtio/virtio_ring.c
View File

@ -3106,4 +3106,73 @@ const struct vring *virtqueue_get_vring(const struct virtqueue *vq)
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring);
/**
* virtqueue_dma_map_single_attrs - map DMA for _vq
* @_vq: the struct virtqueue we're talking about.
* @ptr: the pointer of the buffer to do dma
* @size: the size of the buffer to do dma
* @dir: DMA direction
* @attrs: DMA Attrs
*
* The caller calls this to do dma mapping in advance. The DMA address can be
* passed to this _vq when it is in pre-mapped mode.
*
* return DMA address. Caller should check that by virtqueue_dma_mapping_error().
*/
dma_addr_t virtqueue_dma_map_single_attrs(struct virtqueue *_vq, void *ptr,
size_t size,
enum dma_data_direction dir,
unsigned long attrs)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (!vq->use_dma_api)
return (dma_addr_t)virt_to_phys(ptr);
return dma_map_single_attrs(vring_dma_dev(vq), ptr, size, dir, attrs);
}
EXPORT_SYMBOL_GPL(virtqueue_dma_map_single_attrs);
/**
* virtqueue_dma_unmap_single_attrs - unmap DMA for _vq
* @_vq: the struct virtqueue we're talking about.
* @addr: the dma address to unmap
* @size: the size of the buffer
* @dir: DMA direction
* @attrs: DMA Attrs
*
* Unmap the address that is mapped by the virtqueue_dma_map_* APIs.
*
*/
void virtqueue_dma_unmap_single_attrs(struct virtqueue *_vq, dma_addr_t addr,
size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (!vq->use_dma_api)
return;
dma_unmap_single_attrs(vring_dma_dev(vq), addr, size, dir, attrs);
}
EXPORT_SYMBOL_GPL(virtqueue_dma_unmap_single_attrs);
/**
* virtqueue_dma_mapping_error - check dma address
* @_vq: the struct virtqueue we're talking about.
* @addr: DMA address
*
* Returns 0 means dma valid. Other means invalid dma address.
*/
int virtqueue_dma_mapping_error(struct virtqueue *_vq, dma_addr_t addr)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (!vq->use_dma_api)
return 0;
return dma_mapping_error(vring_dma_dev(vq), addr);
}
EXPORT_SYMBOL_GPL(virtqueue_dma_mapping_error);
MODULE_LICENSE("GPL");

8
include/linux/virtio.h
View File

@ -9,6 +9,7 @@
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/gfp.h>
#include <linux/dma-mapping.h>
/**
* struct virtqueue - a queue to register buffers for sending or receiving.
@ -212,4 +213,11 @@ void unregister_virtio_driver(struct virtio_driver *drv);
#define module_virtio_driver(__virtio_driver) \
module_driver(__virtio_driver, register_virtio_driver, \
unregister_virtio_driver)
dma_addr_t virtqueue_dma_map_single_attrs(struct virtqueue *_vq, void *ptr, size_t size,
enum dma_data_direction dir, unsigned long attrs);
void virtqueue_dma_unmap_single_attrs(struct virtqueue *_vq, dma_addr_t addr,
size_t size, enum dma_data_direction dir,
unsigned long attrs);
int virtqueue_dma_mapping_error(struct virtqueue *_vq, dma_addr_t addr);
#endif /* _LINUX_VIRTIO_H */