On Thu, Feb 02, 2023 at 07:00:32PM +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().
No this looks like the implementation not the purpose. I am guessing the purpose is to keep memory mapped across multiple add/get buf operations right? > Added virtio_dma_unmap() for unmap DMA address. > > Signed-off-by: Xuan Zhuo <[email protected]> > --- > drivers/virtio/virtio_ring.c | 80 ++++++++++++++++++++++++++++++++++++ > include/linux/virtio.h | 9 ++++ > 2 files changed, 89 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 7dfce7001f9f..67eda7bc23ea 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -3022,4 +3022,84 @@ const struct vring *virtqueue_get_vring(struct > virtqueue *vq) > } > EXPORT_SYMBOL_GPL(virtqueue_get_vring); > > +/** > + * virtio_dma_map_page - get the DMA addr of the memory for virtio device > + * @dev: 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. DMA_MAPPING_ERROR means error. > + */ > +dma_addr_t virtio_dma_map_page(struct device *dev, struct page *page, size_t > offset, > + unsigned int length, enum dma_data_direction dir) > +{ > + struct virtio_device *vdev = dev_to_virtio(dev); > + > + if (!vring_use_dma_api(vdev)) > + return page_to_phys(page) + offset; > + > + return dma_map_page(vdev->dev.parent, page, offset, length, dir); > +} > + > +/** > + * virtio_dma_map - get the DMA addr of the memory for virtio device > + * @dev: virtio device > + * @addr: the addr to DMA > + * @length: memory length > + * @dir: DMA direction > + * > + * Returns the DMA addr. > + */ > +dma_addr_t virtio_dma_map(struct device *dev, void *addr, unsigned int > length, > + enum dma_data_direction dir) > +{ > + struct page *page; > + size_t offset; > + > + page = virt_to_page(addr); > + offset = offset_in_page(addr); > + > + return virtio_dma_map_page(dev, page, offset, length, dir); > +} > +EXPORT_SYMBOL_GPL(virtio_dma_map); > + > +/** > + * virtio_dma_mapping_error - check dma address > + * @dev: virtio device > + * @addr: DMA address > + * > + * Returns 0 means dma valid. Other means invalid dma address. > + */ > +int virtio_dma_mapping_error(struct device *dev, dma_addr_t addr) > +{ > + struct virtio_device *vdev = dev_to_virtio(dev); > + > + if (!vring_use_dma_api(vdev)) > + return 0; > + > + return dma_mapping_error(vdev->dev.parent, addr); > +} > +EXPORT_SYMBOL_GPL(virtio_dma_mapping_error); > + > +/** > + * virtio_dma_unmap - unmap DMA addr > + * @dev: virtio device > + * @dma: DMA address > + * @length: memory length > + * @dir: DMA direction > + */ > +void virtio_dma_unmap(struct device *dev, dma_addr_t dma, unsigned int > length, > + enum dma_data_direction dir) > +{ > + struct virtio_device *vdev = dev_to_virtio(dev); > + > + 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 3ca2edb1aef3..ce89126becc5 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> > > /** > * struct virtqueue - a queue to register buffers for sending or receiving. > @@ -218,4 +219,12 @@ 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_page(struct device *dev, struct page *page, size_t > offset, > + unsigned int length, enum dma_data_direction > dir); > +dma_addr_t virtio_dma_map(struct device *dev, void *addr, unsigned int > length, > + enum dma_data_direction dir); > +int virtio_dma_mapping_error(struct device *dev, dma_addr_t addr); > +void virtio_dma_unmap(struct device *dev, dma_addr_t dma, unsigned int > length, > + enum dma_data_direction dir); > #endif /* _LINUX_VIRTIO_H */ > -- > 2.32.0.3.g01195cf9f _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
