[PATCH V3 2/9] virtio_ring: switch to use dma_{map|unmap}_page()

[Jason Wang]

This patch switches to use dma_{map|unmap}_page() to reduce the
coverage of DMA operations. This would help for the following rework
on the virtio map operations.

Reviewed-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/virtio/virtio_ring.c | 55 +++++++++++++++---------------------
 1 file changed, 23 insertions(+), 32 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 103bad8cffff..75e5f6336c8d 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -405,8 +405,8 @@ static dma_addr_t vring_map_single(const struct 
vring_virtqueue *vq,
        if (!vq->use_dma_api)
                return (dma_addr_t)virt_to_phys(cpu_addr);
 
-       return dma_map_single(vring_dma_dev(vq),
-                             cpu_addr, size, direction);
+       return virtqueue_dma_map_single_attrs(&vq->vq, cpu_addr,
+                                             size, direction, 0);
 }
 
 static int vring_mapping_error(const struct vring_virtqueue *vq,
@@ -451,22 +451,14 @@ static unsigned int vring_unmap_one_split(const struct 
vring_virtqueue *vq,
        if (flags & VRING_DESC_F_INDIRECT) {
                if (!vq->use_dma_api)
                        goto out;
+       } else if (!vring_need_unmap_buffer(vq, extra))
+               goto out;
 
-               dma_unmap_single(vring_dma_dev(vq),
-                                extra->addr,
-                                extra->len,
-                                (flags & VRING_DESC_F_WRITE) ?
-                                DMA_FROM_DEVICE : DMA_TO_DEVICE);
-       } else {
-               if (!vring_need_unmap_buffer(vq, extra))
-                       goto out;
-
-               dma_unmap_page(vring_dma_dev(vq),
-                              extra->addr,
-                              extra->len,
-                              (flags & VRING_DESC_F_WRITE) ?
-                              DMA_FROM_DEVICE : DMA_TO_DEVICE);
-       }
+       dma_unmap_page(vring_dma_dev(vq),
+                      extra->addr,
+                      extra->len,
+                      (flags & VRING_DESC_F_WRITE) ?
+                      DMA_FROM_DEVICE : DMA_TO_DEVICE);
 
 out:
        return extra->next;
@@ -1276,20 +1268,13 @@ static void vring_unmap_extra_packed(const struct 
vring_virtqueue *vq,
        if (flags & VRING_DESC_F_INDIRECT) {
                if (!vq->use_dma_api)
                        return;
+       } else if (!vring_need_unmap_buffer(vq, extra))
+               return;
 
-               dma_unmap_single(vring_dma_dev(vq),
-                                extra->addr, extra->len,
-                                (flags & VRING_DESC_F_WRITE) ?
-                                DMA_FROM_DEVICE : DMA_TO_DEVICE);
-       } else {
-               if (!vring_need_unmap_buffer(vq, extra))
-                       return;
-
-               dma_unmap_page(vring_dma_dev(vq),
-                              extra->addr, extra->len,
-                              (flags & VRING_DESC_F_WRITE) ?
-                              DMA_FROM_DEVICE : DMA_TO_DEVICE);
-       }
+       dma_unmap_page(vring_dma_dev(vq),
+                      extra->addr, extra->len,
+                      (flags & VRING_DESC_F_WRITE) ?
+                      DMA_FROM_DEVICE : DMA_TO_DEVICE);
 }
 
 static struct vring_packed_desc *alloc_indirect_packed(unsigned int total_sg,
@@ -3161,7 +3146,13 @@ dma_addr_t virtqueue_dma_map_single_attrs(const struct 
virtqueue *_vq, void *ptr
                return (dma_addr_t)virt_to_phys(ptr);
        }
 
-       return dma_map_single_attrs(vring_dma_dev(vq), ptr, size, dir, attrs);
+       /* DMA must never operate on areas that might be remapped. */
+       if (dev_WARN_ONCE(&_vq->vdev->dev, is_vmalloc_addr(ptr),
+                         "rejecting DMA map of vmalloc memory\n"))
+               return DMA_MAPPING_ERROR;
+
+       return dma_map_page_attrs(vring_dma_dev(vq), virt_to_page(ptr),
+                                 offset_in_page(ptr), size, dir, attrs);
 }
 EXPORT_SYMBOL_GPL(virtqueue_dma_map_single_attrs);
 
@@ -3186,7 +3177,7 @@ void virtqueue_dma_unmap_single_attrs(const struct 
virtqueue *_vq,
        if (!vq->use_dma_api)
                return;
 
-       dma_unmap_single_attrs(vring_dma_dev(vq), addr, size, dir, attrs);
+       dma_unmap_page_attrs(vring_dma_dev(vq), addr, size, dir, attrs);
 }
 EXPORT_SYMBOL_GPL(virtqueue_dma_unmap_single_attrs);
 
-- 
2.42.0