With the misc device, we should end up using the result of get_arch_dma_ops(..) or dma-direct ops.
This can allow us to have WC mappings in the guest after synchronization.
Signed-off-by: Gurchetan Singh gurchetansingh@chromium.org --- drivers/dma-buf/udmabuf.c | 40 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c index 67e89bb034c5..142444922acd 100644 --- a/drivers/dma-buf/udmabuf.c +++ b/drivers/dma-buf/udmabuf.c @@ -19,6 +19,7 @@ struct udmabuf { u32 flags; pgoff_t pagecount; struct page **pages; + struct sg_table *sg; struct miscdevice *device; };
@@ -105,8 +106,12 @@ static void unmap_udmabuf(struct dma_buf_attachment *at, static void release_udmabuf(struct dma_buf *buf) { struct udmabuf *ubuf = buf->priv; + struct device *dev = ubuf->device->this_device; pgoff_t pg;
+ if (ubuf->sg) + put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL); + for (pg = 0; pg < ubuf->pagecount; pg++) put_page(ubuf->pages[pg]); kfree(ubuf->pages); @@ -127,6 +132,39 @@ static void kunmap_udmabuf(struct dma_buf *buf, unsigned long page_num, kunmap(vaddr); }
+static int begin_cpu_udmabuf(struct dma_buf *buf, + enum dma_data_direction direction) +{ + struct udmabuf *ubuf = buf->priv; + struct device *dev = ubuf->device->this_device; + + if (!ubuf->sg) { + ubuf->sg = get_sg_table(dev, buf, direction); + if (IS_ERR(ubuf->sg)) + return PTR_ERR(ubuf->sg); + } else { + dma_sync_sg_for_device(dev, ubuf->sg->sgl, + ubuf->sg->nents, + direction); + } + + return 0; +} + +static int end_cpu_udmabuf(struct dma_buf *buf, + enum dma_data_direction direction) +{ + struct udmabuf *ubuf = buf->priv; + struct device *dev = ubuf->device->this_device; + + if (!ubuf->sg) + return -EINVAL; + + dma_sync_sg_for_cpu(dev, ubuf->sg->sgl, ubuf->sg->nents, direction); + return 0; +} + + static const struct dma_buf_ops udmabuf_ops = { .cache_sgt_mapping = true, .map_dma_buf = map_udmabuf, @@ -135,6 +173,8 @@ static const struct dma_buf_ops udmabuf_ops = { .map = kmap_udmabuf, .unmap = kunmap_udmabuf, .mmap = mmap_udmabuf, + .begin_cpu_access = begin_cpu_udmabuf, + .end_cpu_access = end_cpu_udmabuf, };
#define SEALS_WANTED (F_SEAL_SHRINK)