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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 9/9] vduse: switch to use virtio map API instead of DMA API Message-ID: <20250701034754-mutt-send-email-mst@kernel.org> References: <20250701011401.74851-1-jasowang@redhat.com> <20250701011401.74851-10-jasowang@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20250701011401.74851-10-jasowang@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: IKxU75Ivu2nPCda3vndsBwWLF8kjcL01ageRvSN7Fa0_1751356207 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Jul 01, 2025 at 09:14:01AM +0800, Jason Wang wrote: > Lacking the support of device specific mapping supported in virtio, > VDUSE must trick the DMA API in order to make virtio-vdpa transport > work. This is done by advertising vDPA device as dma device with a > VDUSE specific dma_ops even if it doesn't do DMA at all. > > This will be fixed by this patch. Thanks to the new mapping operations > support by virtio and vDPA. VDUSE can simply switch to advertise its > specific mappings operations to virtio via virtio-vdpa then DMA API is > not needed for VDUSE any more. > > Signed-off-by: Jason Wang so what exactly is the issue fixed by all this pile of code? I just don't really see it. yes the existing thing is a hack but at least it is isolated within vduse which let's be frank is not it's only issue. > --- > drivers/vdpa/vdpa_user/iova_domain.c | 2 +- > drivers/vdpa/vdpa_user/iova_domain.h | 2 +- > drivers/vdpa/vdpa_user/vduse_dev.c | 31 ++++++++++++++++------------ > 3 files changed, 20 insertions(+), 15 deletions(-) > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c > index 019f3305c0ac..8ea311692545 100644 > --- a/drivers/vdpa/vdpa_user/iova_domain.c > +++ b/drivers/vdpa/vdpa_user/iova_domain.c > @@ -447,7 +447,7 @@ void vduse_domain_unmap_page(struct vduse_iova_domain *domain, > > void *vduse_domain_alloc_coherent(struct vduse_iova_domain *domain, > size_t size, dma_addr_t *dma_addr, > - gfp_t flag, unsigned long attrs) > + gfp_t flag) > { > struct iova_domain *iovad = &domain->consistent_iovad; > unsigned long limit = domain->iova_limit; > diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h > index 846572b95c23..a2316571671f 100644 > --- a/drivers/vdpa/vdpa_user/iova_domain.h > +++ b/drivers/vdpa/vdpa_user/iova_domain.h > @@ -64,7 +64,7 @@ void vduse_domain_unmap_page(struct vduse_iova_domain *domain, > > void *vduse_domain_alloc_coherent(struct vduse_iova_domain *domain, > size_t size, dma_addr_t *dma_addr, > - gfp_t flag, unsigned long attrs); > + gfp_t flag); > > void vduse_domain_free_coherent(struct vduse_iova_domain *domain, size_t size, > void *vaddr, dma_addr_t dma_addr, > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > index 64bc39722007..f86d7111e103 100644 > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > @@ -814,51 +814,55 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = { > .free = vduse_vdpa_free, > }; > > -static void vduse_dev_sync_single_for_device(struct device *dev, > +static void vduse_dev_sync_single_for_device(void *token, > dma_addr_t dma_addr, size_t size, > enum dma_data_direction dir) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > > vduse_domain_sync_single_for_device(domain, dma_addr, size, dir); > } > > -static void vduse_dev_sync_single_for_cpu(struct device *dev, > +static void vduse_dev_sync_single_for_cpu(void *token, > dma_addr_t dma_addr, size_t size, > enum dma_data_direction dir) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > > vduse_domain_sync_single_for_cpu(domain, dma_addr, size, dir); > } > > -static dma_addr_t vduse_dev_map_page(struct device *dev, struct page *page, > +static dma_addr_t vduse_dev_map_page(void *token, struct page *page, > unsigned long offset, size_t size, > enum dma_data_direction dir, > unsigned long attrs) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > > return vduse_domain_map_page(domain, page, offset, size, dir, attrs); > } > > -static void vduse_dev_unmap_page(struct device *dev, dma_addr_t dma_addr, > +static void vduse_dev_unmap_page(void *token, dma_addr_t dma_addr, > size_t size, enum dma_data_direction dir, > unsigned long attrs) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > > return vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs); > } > > -static void *vduse_dev_alloc_coherent(struct device *dev, size_t size, > - dma_addr_t *dma_addr, gfp_t flag, > - unsigned long attrs) > +static void *vduse_dev_alloc_coherent(void *token, size_t size, > + dma_addr_t *dma_addr, gfp_t flag) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > unsigned long iova; > @@ -866,7 +870,7 @@ static void *vduse_dev_alloc_coherent(struct device *dev, size_t size, > > *dma_addr = DMA_MAPPING_ERROR; > addr = vduse_domain_alloc_coherent(domain, size, > - (dma_addr_t *)&iova, flag, attrs); > + (dma_addr_t *)&iova, flag); > if (!addr) > return NULL; > > @@ -875,25 +879,27 @@ static void *vduse_dev_alloc_coherent(struct device *dev, size_t size, > return addr; > } > > -static void vduse_dev_free_coherent(struct device *dev, size_t size, > +static void vduse_dev_free_coherent(void *token, size_t size, > void *vaddr, dma_addr_t dma_addr, > unsigned long attrs) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > > vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs); > } > > -static size_t vduse_dev_max_mapping_size(struct device *dev) > +static size_t vduse_dev_max_mapping_size(void *token) > { > + struct device *dev = token; > struct vduse_dev *vdev = dev_to_vduse(dev); > struct vduse_iova_domain *domain = vdev->domain; > > return domain->bounce_size; > } > > -static const struct dma_map_ops vduse_dev_dma_ops = { > +static const struct virtio_map_ops vduse_map_ops = { > .sync_single_for_device = vduse_dev_sync_single_for_device, > .sync_single_for_cpu = vduse_dev_sync_single_for_cpu, > .map_page = vduse_dev_map_page, > @@ -2009,7 +2015,7 @@ static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name) > return -EEXIST; > > vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, dev->dev, > - &vduse_vdpa_config_ops, NULL, > + &vduse_vdpa_config_ops, &vduse_map_ops, > 1, 1, name, true); > if (IS_ERR(vdev)) > return PTR_ERR(vdev); > @@ -2022,7 +2028,6 @@ static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name) > put_device(&vdev->vdpa.dev); > return ret; > } > - set_dma_ops(&vdev->vdpa.dev, &vduse_dev_dma_ops); > vdev->vdpa.map_token = &vdev->vdpa.dev; > vdev->vdpa.mdev = &vduse_mgmt->mgmt_dev; > > -- > 2.34.1