On Fri, 18 Feb 2022 04:24:58 -0500, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > On Fri, Feb 18, 2022 at 04:55:23PM +0800, Xuan Zhuo wrote: > > On Thu, 17 Feb 2022 15:19:44 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > On Thu, Feb 10, 2022 at 4:51 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > virtqueue_add() only supports virtual addresses, dma is completed in > > > > virtqueue_add(). > > > > > > > > In some scenarios (such as the AF_XDP scenario), DMA is completed in advance, so > > > > it is necessary for us to support passing the DMA address to virtqueue_add(). > > > > > > I'd suggest rename this feature as "unmanaged DMA". > > > > OK > > IIUC when you say "dma is completed" you really mean "memory is mapped > for dma". What is special is that virtio suddenly gets s/g that is > already mapped for DMA, not in the way DMA (direct memory access) itself > happens. right? Pls document as such. > And this is why I'd call this flag "mapped" or "premapped", not > "predma". "unmanaged" is also ok, though it's a bit vague wrt what > exactly is managed. > I'll defer to Jason on this. Jason what do you prefer? OK. Thanks > > > > > > > > > > > > Record this predma information in extra->flags, which can be skipped when > > > > executing dma unmap. > > > > > > Question still, can we use per-virtqueue flag instead of per > > > descriptor flag? If my memory is correct, the answer is yes in the > > > discussion for the previous version. > > > > > > > Yes. > > > > per-virtqueue? I guess it should be per-submit. > > > > This patch set only adds a flag to desc_extra[head].flags, so that we can know > > if we need to unmap dma when we detach. > > > > Thanks. > > > > > Thanks > > > > > > > > > > > v1: > > > > 1. All sgs requested at one time are required to be unified PREDMA, and several > > > > of them are not supported to be PREDMA > > > > 2. virtio_dma_map() is removed from this patch set and will be submitted > > > > together with the next time AF_XDP supports virtio dma > > > > 3. Added patch #2 #3 to remove the check for flags when performing unmap > > > > indirect desc > > > > > > > > Xuan Zhuo (6): > > > > virtio: rename vring_unmap_state_packed() to > > > > vring_unmap_extra_packed() > > > > virtio: remove flags check for unmap split indirect desc > > > > virtio: remove flags check for unmap packed indirect desc > > > > virtio: virtqueue_add() support predma > > > > virtio: split: virtqueue_add_split() support dma address > > > > virtio: packed: virtqueue_add_packed() support dma address > > > > > > > > drivers/virtio/virtio_ring.c | 199 ++++++++++++++++++++++------------- > > > > 1 file changed, 126 insertions(+), 73 deletions(-) > > > > > > > > -- > > > > 2.31.0 > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
