Jason Wang
2023-Feb-21 01:51 UTC
[PATCH vhost 07/10] virtio_ring: add api virtio_dma_map() for advance dma
On Mon, Feb 20, 2023 at 3:02 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:> > On Mon, 20 Feb 2023 13:38:24 +0800, Jason Wang <jasowang at redhat.com> wrote: > > On Tue, Feb 14, 2023 at 3:27 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > > > Added virtio_dma_map() to map DMA addresses for virtual memory in > > > advance. The purpose is to keep memory mapped across multiple add/get > > > buf operations. > > > > I wonder if instead of exporting helpers like this, it might be simple > > to just export dma_dev then the upper layer can use DMA API at will? > > > The reason for not doing this, Virtio is not just using DMA_DEV to mapp, but > also check whether DMA is used.We should let the DMA API decide by exporting a correct dma_dev. E.g when ACCESS_PLATFORM is not negotiated, advertising a DMA dev without dma_ops. Thanks> > > > > > (Otherwise the DMA helpers need to grow/shrink as the DMA API evolves?) > > > > > > > > Added virtio_dma_unmap() for unmap DMA address. > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > > --- > > > drivers/virtio/virtio_ring.c | 92 ++++++++++++++++++++++++++++++++++++ > > > include/linux/virtio.h | 9 ++++ > > > 2 files changed, 101 insertions(+) > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > index cd9364eb2345..855338609c7f 100644 > > > --- a/drivers/virtio/virtio_ring.c > > > +++ b/drivers/virtio/virtio_ring.c > > > @@ -3172,4 +3172,96 @@ 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 > > > + * > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > + * core handles DMA API internally. > > > + * > > > + * 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) > > > +{ > > > > This (and the reset) needs to be done per virtqueue instead per device > > after b0e504e5505d184b0be248b7dcdbe50b79f03758 ("virtio_ring: per > > virtqueue dma device"). > > > YES. > > > > > > > + 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); > > > +} > > > > Need either inline or EXPORT_SYMBOL_GPL() here. > > Because I did not use this interface, I did not export it. > > Thanks. > > > > > > Thanks > > > > > > > + > > > +/** > > > + * 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 > > > + * > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > + * core handles DMA API internally. > > > + * > > > + * 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 > > > + * > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > + * core handles DMA API internally. > > > + * > > > + * 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 > > > + * > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > + * core handles DMA API internally. > > > + */ > > > +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 3ebb346ebb7c..b5fa71476737 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. > > > @@ -216,4 +217,12 @@ 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 > > > > > >
Xuan Zhuo
2023-Feb-28 11:15 UTC
[PATCH vhost 07/10] virtio_ring: add api virtio_dma_map() for advance dma
On Tue, 21 Feb 2023 09:51:07 +0800, Jason Wang <jasowang at redhat.com> wrote:> On Mon, Feb 20, 2023 at 3:02 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > On Mon, 20 Feb 2023 13:38:24 +0800, Jason Wang <jasowang at redhat.com> wrote: > > > On Tue, Feb 14, 2023 at 3:27 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > > > > > Added virtio_dma_map() to map DMA addresses for virtual memory in > > > > advance. The purpose is to keep memory mapped across multiple add/get > > > > buf operations. > > > > > > I wonder if instead of exporting helpers like this, it might be simple > > > to just export dma_dev then the upper layer can use DMA API at will? > > > > > > The reason for not doing this, Virtio is not just using DMA_DEV to mapp, but > > also check whether DMA is used. > > We should let the DMA API decide by exporting a correct dma_dev. E.g > when ACCESS_PLATFORM is not negotiated, advertising a DMA dev without > dma_ops.Do you mean we provide this API? virtio_get_dma_dev() If it returns NULL, the caller will use the physical memory address directly. If this func return a dma_dev, the caller should use DMA API. Thanks.> > Thanks > > > > > > > > > > > (Otherwise the DMA helpers need to grow/shrink as the DMA API evolves?) > > > > > > > > > > > Added virtio_dma_unmap() for unmap DMA address. > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > > > --- > > > > drivers/virtio/virtio_ring.c | 92 ++++++++++++++++++++++++++++++++++++ > > > > include/linux/virtio.h | 9 ++++ > > > > 2 files changed, 101 insertions(+) > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > index cd9364eb2345..855338609c7f 100644 > > > > --- a/drivers/virtio/virtio_ring.c > > > > +++ b/drivers/virtio/virtio_ring.c > > > > @@ -3172,4 +3172,96 @@ 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + * > > > > + * 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) > > > > +{ > > > > > > This (and the reset) needs to be done per virtqueue instead per device > > > after b0e504e5505d184b0be248b7dcdbe50b79f03758 ("virtio_ring: per > > > virtqueue dma device"). > > > > > > YES. > > > > > > > > > > > + 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); > > > > +} > > > > > > Need either inline or EXPORT_SYMBOL_GPL() here. > > > > Because I did not use this interface, I did not export it. > > > > Thanks. > > > > > > > > > > Thanks > > > > > > > > > > + > > > > +/** > > > > + * 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + * > > > > + * 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + * > > > > + * 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + */ > > > > +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 3ebb346ebb7c..b5fa71476737 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. > > > > @@ -216,4 +217,12 @@ 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 > > > > > > > > > >
Xuan Zhuo
2023-Mar-01 11:47 UTC
[PATCH vhost 07/10] virtio_ring: add api virtio_dma_map() for advance dma
On Tue, 21 Feb 2023 09:51:07 +0800, Jason Wang <jasowang at redhat.com> wrote:> On Mon, Feb 20, 2023 at 3:02 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > On Mon, 20 Feb 2023 13:38:24 +0800, Jason Wang <jasowang at redhat.com> wrote: > > > On Tue, Feb 14, 2023 at 3:27 PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > > > > > Added virtio_dma_map() to map DMA addresses for virtual memory in > > > > advance. The purpose is to keep memory mapped across multiple add/get > > > > buf operations. > > > > > > I wonder if instead of exporting helpers like this, it might be simple > > > to just export dma_dev then the upper layer can use DMA API at will? > > > > > > The reason for not doing this, Virtio is not just using DMA_DEV to mapp, but > > also check whether DMA is used. > > We should let the DMA API decide by exporting a correct dma_dev. E.g > when ACCESS_PLATFORM is not negotiated, advertising a DMA dev without > dma_ops.In XSK, we need to pass a device to XSK. If vdev->dev is passed, we can't get dma_dev in XSK. Because each VQ has a dma_dev. So we should pass dma_dev to XSK. But how do we determine whether to use DMA_OPS based on dma_dev? At present, my API design, the caller should determine whether it is a Virtio device. If we also need the caller to determine whether to use DMA_OPS, this is too unfriendly for the caller. Thanks.> > Thanks > > > > > > > > > > > (Otherwise the DMA helpers need to grow/shrink as the DMA API evolves?) > > > > > > > > > > > Added virtio_dma_unmap() for unmap DMA address. > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > > > --- > > > > drivers/virtio/virtio_ring.c | 92 ++++++++++++++++++++++++++++++++++++ > > > > include/linux/virtio.h | 9 ++++ > > > > 2 files changed, 101 insertions(+) > > > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > > index cd9364eb2345..855338609c7f 100644 > > > > --- a/drivers/virtio/virtio_ring.c > > > > +++ b/drivers/virtio/virtio_ring.c > > > > @@ -3172,4 +3172,96 @@ 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + * > > > > + * 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) > > > > +{ > > > > > > This (and the reset) needs to be done per virtqueue instead per device > > > after b0e504e5505d184b0be248b7dcdbe50b79f03758 ("virtio_ring: per > > > virtqueue dma device"). > > > > > > YES. > > > > > > > > > > > + 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); > > > > +} > > > > > > Need either inline or EXPORT_SYMBOL_GPL() here. > > > > Because I did not use this interface, I did not export it. > > > > Thanks. > > > > > > > > > > Thanks > > > > > > > > > > + > > > > +/** > > > > + * 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + * > > > > + * 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + * > > > > + * 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 > > > > + * > > > > + * This API is only for pre-mapped buffers, for non premapped buffers virtio > > > > + * core handles DMA API internally. > > > > + */ > > > > +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 3ebb346ebb7c..b5fa71476737 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. > > > > @@ -216,4 +217,12 @@ 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 > > > > > > > > > >