search for: premapped

On Fri, Jun 02, 2023 at 05:22:06PM +0800, Xuan Zhuo wrote: > Introduce the module param "experiment_premapped" to enable the function > that the virtio-net do dma mapping. > > If that is true, the vq of virtio-net is under the premapped mode. > It just handle the sg with dma_address. And the driver must get the dma > address of the buffer to unmap after get the buffer from virtio core....

...evices. 2. I tried to let xsk support callballs to get phy address from virtio-net driver as the dma address. But the maintainers of xsk may want to use dma-buf to replace the DMA APIs. I think that may be a larger effort. We will wait too long. So rethinking this, firstly, we can support premapped-dma only for devices with VIRTIO_F_ACCESS_PLATFORM. In the case of af-xdp, if the users want to use it, they have to update the device to support VIRTIO_F_RING_RESET, and they can also enable the device's VIRTIO_F_ACCESS_PLATFORM feature. Thanks for the help from Christoph. =================...

...evices. 2. I tried to let xsk support callballs to get phy address from virtio-net driver as the dma address. But the maintainers of xsk may want to use dma-buf to replace the DMA APIs. I think that may be a larger effort. We will wait too long. So rethinking this, firstly, we can support premapped-dma only for devices with VIRTIO_F_ACCESS_PLATFORM. In the case of af-xdp, if the users want to use it, they have to update the device to support VIRTIO_F_RING_RESET, and they can also enable the device's VIRTIO_F_ACCESS_PLATFORM feature. Thanks for the help from Christoph. =================...

...> > +++ b/drivers/virtio/virtio_ring.c > > @@ -70,6 +70,7 @@ > > struct vring_desc_state_split { > > void *data; /* Data for callback. */ > > struct vring_desc *indir_desc; /* Indirect descriptor, if any. */ > > + bool premapped; > > Better with a comment. > > Not native speaker, but "dma_addr" might be better? > > > }; > > > > struct vring_desc_state_packed { > > @@ -440,7 +441,7 @@ static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq, > > }...

...evices. 2. I tried to let xsk support callballs to get phy address from virtio-net driver as the dma address. But the maintainers of xsk may want to use dma-buf to replace the DMA APIs. I think that may be a larger effort. We will wait too long. So rethinking this, firstly, we can support premapped-dma only for devices with VIRTIO_F_ACCESS_PLATFORM. In the case of af-xdp, if the users want to use it, they have to update the device to support VIRTIO_F_RING_RESET, and they can also enable the device's VIRTIO_F_ACCESS_PLATFORM feature. Thanks for the help from Christoph. =================...

virtuque_add() adds parameter premapped. Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- drivers/virtio/virtio_ring.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 1ffab1eb40c0..e2fc50c05bec 100644 --- a/drivers/virtio/vi...

...evices. 2. I tried to let xsk support callballs to get phy address from virtio-net driver as the dma address. But the maintainers of xsk may want to use dma-buf to replace the DMA APIs. I think that may be a larger effort. We will wait too long. So rethinking this, firstly, we can support premapped-dma only for devices with VIRTIO_F_ACCESS_PLATFORM. In the case of af-xdp, if the users want to use it, they have to update the device to support VIRTIO_F_RING_RESET, and they can also enable the device's VIRTIO_F_ACCESS_PLATFORM feature. Thanks for the help from Christoph. =================...

...33% | 1192064 recv by sockperf: 100% | 68% | 100% | 692288 recv by xsk: 100% | 33% | 43% | 771670 Before achieving the function of Virtio-Net, we also have to let virtio core support these features: 1. virtio core support premapped 2. virtio core support reset per-queue 3. introduce DMA APIs to virtio core Please review. Thanks. Xuan Zhuo (10): virtio_ring: split: refactor virtqueue_add_split() for premapped virtio_ring: packed: separate prepare code from virtuque_add_indirect_packed() virtio_ring: packed: refact...

On Wed, May 17, 2023 at 10:22:41AM +0800, Xuan Zhuo wrote: > virtuque_add() adds parameter premapped. Well, I can see that. But why?

On Mon, May 22, 2023 at 11:03:26PM -0700, Christoph Hellwig wrote: > On Wed, May 17, 2023 at 10:22:41AM +0800, Xuan Zhuo wrote: > > virtuque_add() adds parameter premapped. > > Well, I can see that. But why? Assuming it's intentional, it should say something along the lines of "The parameter is unused for now, and all callers just pass false. It will be used by a follow-up patch". It's not a bad way to split patches, this way actual logic...

...ing internal logic like > virtio_dma_need_sync() over hiding it in > virtio_dma_sync_single_range_for_cpu() and > virtio_dma_sync_single_range_for_device()? Sorry, I didn't understand it. Thanks. > > Thanks > > > > > > These APIs can be used together with the premapped mechanism to sync the > > DMA address. > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > --- > > drivers/virtio/virtio_ring.c | 70 ++++++++++++++++++++++++++++++++++++ > > include/linux/virtio.h | 8 +++++ > > 2 files chang...

...tio 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, > > > +...

...tio 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, > > > +...

...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, > > + unsi...

On Fri, Jun 02, 2023 at 05:22:01PM +0800, Xuan Zhuo wrote: > Under the premapped mode, the driver needs to unmap the DMA address > after receiving the buffer. The virtio core records the DMA address, > so the driver needs a way to get the dma info from the virtio core. > > A straightforward approach is to pass an array to the virtio core when > calling virtqueue...

...rations. The first function includes all codes that may fail before the DMA operation. The subsequent part is used as the second function. In this way, we can perform DMA operations in the middle of the two functions. If the first function fails, we do not need to perform DMA operations. If it is premapped, we can pass the DMA operation. Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- drivers/virtio/virtio_ring.c | 131 +++++++++++++++++++++++------------ 1 file changed, 88 insertions(+), 43 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c in...

...o_le64(addr); desc[i].len = cpu_to_le32(sg->length); i++; + if (n >= out_sgs) + buflen += sg->length; } } @@ -1379,6 +1429,10 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, vq->packed.desc_state[id].last = id; vq->packed.desc_state[id].premapped = premapped; + /* Store in buffer length if necessary */ + if (vq->packed.buflen) + vq->packed.buflen[id] = buflen; + vq->num_added += 1; pr_debug("Added buffer head %i to %p\n", head, vq); @@ -1416,6 +1470,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_v...

...he 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, stru...

...; > > > > + * @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...

...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. > > > > > > > > > + */ &...