Commit 284562e1 authored by Gurchetan Singh's avatar Gurchetan Singh Committed by Gerd Hoffmann
Browse files

udmabuf: implement begin_cpu_access/end_cpu_access hooks 



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: default avatarGurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20191203013627.85991-4-gurchetansingh@chromium.org


Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 17a7ce20

drivers/dma-buf/udmabuf.c

+39 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ static const size_t size_limit_mb = 64; /* total dmabuf size, in megabytes */ 
struct udmabuf {

	pgoff_t pagecount;

	struct page **pages;

	struct sg_table *sg;

	struct miscdevice *device;

};
@@ -98,20 +99,58 @@ 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);

	kfree(ubuf);

}



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,

	.unmap_dma_buf	   = unmap_udmabuf,

	.release	   = release_udmabuf,

	.mmap		   = mmap_udmabuf,

	.begin_cpu_access  = begin_cpu_udmabuf,

	.end_cpu_access    = end_cpu_udmabuf,

};



#define SEALS_WANTED (F_SEAL_SHRINK)

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