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Tsirkin" To: Jason Wang Cc: xuanzhuo@linux.alibaba.com, eperezma@redhat.com, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, hch@infradead.org, xieyongji@bytedance.com Subject: Re: [PATCH 0/9] Refine virtio mapping API Message-ID: <20250701030150-mutt-send-email-mst@kernel.org> References: <20250701011401.74851-1-jasowang@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250701011401.74851-1-jasowang@redhat.com> On Tue, Jul 01, 2025 at 09:13:52AM +0800, Jason Wang wrote: > Hi all: > > Virtio used to be coupled with DMA API. This works fine for the device > that do real DMA but not the others. For example, VDUSE nees to craft > with DMA API in order to let the virtio-vdpa driver to work. > > This series tries to solve this issue by introducing the mapping API > in the virtio core. So transport like vDPA can implement their own > mapping logic without the need to hack with DMA API. The mapping API > are abstracted with a new map operations in order to be re-used by > transprot or device. So device like VDUSE can implement its own > mapping loigc. > > Please review. > > Thanks Cost of all this extra indirection? Especially on systems with software spectre mitigations/retpoline enabled. > Jason Wang (9): > virtio_ring: constify virtqueue pointer for DMA helpers > virtio_ring: switch to use dma_{map|unmap}_page() > virtio: rename dma helpers > virtio: rename dma_dev to map_token > virtio_ring: rename dma_handle to map_handle > virtio: introduce map ops in virtio core > vdpa: rename dma_dev to map_token > vdpa: introduce map ops > vduse: switch to use virtio map API instead of DMA API > > drivers/net/virtio_net.c | 32 +- > drivers/vdpa/alibaba/eni_vdpa.c | 5 +- > drivers/vdpa/ifcvf/ifcvf_main.c | 5 +- > drivers/vdpa/octeon_ep/octep_vdpa_main.c | 6 +- > drivers/vdpa/pds/vdpa_dev.c | 3 +- > drivers/vdpa/solidrun/snet_main.c | 4 +- > drivers/vdpa/vdpa.c | 5 +- > drivers/vdpa/vdpa_sim/vdpa_sim.c | 4 +- > drivers/vdpa/vdpa_user/iova_domain.c | 8 +- > drivers/vdpa/vdpa_user/iova_domain.h | 5 +- > drivers/vdpa/vdpa_user/vduse_dev.c | 34 +- > drivers/vdpa/virtio_pci/vp_vdpa.c | 5 +- > drivers/vhost/vdpa.c | 11 +- > drivers/virtio/virtio_ring.c | 440 ++++++++++++++--------- > drivers/virtio/virtio_vdpa.c | 15 +- > include/linux/vdpa.h | 22 +- > include/linux/virtio.h | 36 +- > include/linux/virtio_config.h | 68 ++++ > include/linux/virtio_ring.h | 6 +- > 19 files changed, 476 insertions(+), 238 deletions(-) > > -- > 2.34.1