Xuan Zhuo
2022-Jan-07 06:33 UTC
[PATCH 6/6] virtio: add api virtio_dma_map() for advance dma
Added virtio_dma_map() to map DMA addresses for virtual memory in
advance. The purpose of adding this function is to check
vring_use_dma_api() for virtio dma operation and get vdev->dev.parent as
the parameter of dma_map_page().
Added virtio_dma_unmap() for unmap DMA address.
Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 47 ++++++++++++++++++++++++++++++++++++
include/linux/virtio.h | 9 +++++++
2 files changed, 56 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index e165bc2e1344..f4a0fb85df27 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2472,4 +2472,51 @@ const struct vring *virtqueue_get_vring(struct virtqueue
*vq)
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring);
+/**
+ * virtio_dma_map - get the DMA addr of the memory for virtio device
+ * @vdev: virtio device
+ * @page: the page of the memory to DMA
+ * @offset: the offset of the memory inside page
+ * @length: memory length
+ * @dir: DMA direction
+ *
+ * Returns the DMA addr. Zero means error.
+ */
+dma_addr_t virtio_dma_map(struct virtio_device *vdev,
+ struct page *page, size_t offset,
+ unsigned int length,
+ enum dma_data_direction dir)
+{
+ dma_addr_t addr;
+
+ if (!vring_use_dma_api(vdev))
+ return page_to_phys(page) + offset;
+
+ addr = dma_map_page(vdev->dev.parent, page, offset, length, dir);
+
+ if (dma_mapping_error(vdev->dev.parent, addr))
+ return 0;
+
+ return addr;
+}
+EXPORT_SYMBOL_GPL(virtio_dma_map);
+
+/**
+ * virtio_dma_unmap - unmap DMA addr
+ * @vdev: virtio device
+ * @dma: DMA address
+ * @length: memory length
+ * @dir: DMA direction
+ */
+void virtio_dma_unmap(struct virtio_device *vdev,
+ dma_addr_t dma, unsigned int length,
+ enum dma_data_direction dir)
+{
+ if (!vring_use_dma_api(vdev))
+ return;
+
+ dma_unmap_page(vdev->dev.parent, dma, length, dir);
+}
+EXPORT_SYMBOL_GPL(virtio_dma_unmap);
+
MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 41edbc01ffa4..6e6c6e18ecf8 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -9,6 +9,7 @@
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/gfp.h>
+#include <linux/dma-mapping.h>
/**
* virtqueue - a queue to register buffers for sending or receiving.
@@ -195,4 +196,12 @@ 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 virtio_dma_map(struct virtio_device *vdev,
+ struct page *page, size_t offset,
+ unsigned int length,
+ enum dma_data_direction dir);
+void virtio_dma_unmap(struct virtio_device *vdev,
+ dma_addr_t dma, unsigned int length,
+ enum dma_data_direction dir);
#endif /* _LINUX_VIRTIO_H */
--
2.31.0
Michael S. Tsirkin
2022-Jan-10 07:12 UTC
[PATCH 6/6] virtio: add api virtio_dma_map() for advance dma
On Fri, Jan 07, 2022 at 02:33:06PM +0800, Xuan Zhuo wrote:> Added virtio_dma_map() to map DMA addresses for virtual memory in > advance. The purpose of adding this function is to check > vring_use_dma_api() for virtio dma operation and get vdev->dev.parent as > the parameter of dma_map_page(). > > Added virtio_dma_unmap() for unmap DMA address. > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>OK but where are the users for this new API?> --- > drivers/virtio/virtio_ring.c | 47 ++++++++++++++++++++++++++++++++++++ > include/linux/virtio.h | 9 +++++++ > 2 files changed, 56 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index e165bc2e1344..f4a0fb85df27 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -2472,4 +2472,51 @@ const struct vring *virtqueue_get_vring(struct virtqueue *vq) > } > EXPORT_SYMBOL_GPL(virtqueue_get_vring); > > +/** > + * virtio_dma_map - get the DMA addr of the memory for virtio device > + * @vdev: virtio device > + * @page: the page of the memory to DMA > + * @offset: the offset of the memory inside page > + * @length: memory length > + * @dir: DMA direction > + * > + * Returns the DMA addr. Zero means error.Should not drivers use a variant of dma_mapping_error to check?> + */ > +dma_addr_t virtio_dma_map(struct virtio_device *vdev, > + struct page *page, size_t offset, > + unsigned int length, > + enum dma_data_direction dir) > +{ > + dma_addr_t addr; > + > + if (!vring_use_dma_api(vdev)) > + return page_to_phys(page) + offset; > + > + addr = dma_map_page(vdev->dev.parent, page, offset, length, dir); > + > + if (dma_mapping_error(vdev->dev.parent, addr)) > + return 0; > + > + return addr; > +} > +EXPORT_SYMBOL_GPL(virtio_dma_map);Yes it's 0, but you should really use DMA_MAPPING_ERROR.> + > +/** > + * virtio_dma_unmap - unmap DMA addr > + * @vdev: virtio device > + * @dma: DMA address > + * @length: memory length > + * @dir: DMA direction > + */ > +void virtio_dma_unmap(struct virtio_device *vdev, > + dma_addr_t dma, unsigned int length, > + enum dma_data_direction dir) > +{ > + if (!vring_use_dma_api(vdev)) > + return; > + > + dma_unmap_page(vdev->dev.parent, dma, length, dir); > +} > +EXPORT_SYMBOL_GPL(virtio_dma_unmap); > + > MODULE_LICENSE("GPL"); > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 41edbc01ffa4..6e6c6e18ecf8 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -9,6 +9,7 @@ > #include <linux/device.h> > #include <linux/mod_devicetable.h> > #include <linux/gfp.h> > +#include <linux/dma-mapping.h> > > /** > * virtqueue - a queue to register buffers for sending or receiving. > @@ -195,4 +196,12 @@ 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 virtio_dma_map(struct virtio_device *vdev, > + struct page *page, size_t offset, > + unsigned int length, > + enum dma_data_direction dir); > +void virtio_dma_unmap(struct virtio_device *vdev, > + dma_addr_t dma, unsigned int length, > + enum dma_data_direction dir); > #endif /* _LINUX_VIRTIO_H */ > -- > 2.31.0