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From 9dc454ebc4380cd90c24a3c224bb0ac7b3d9cc29 Mon Sep 17 00:00:00 2001
From: Gurchetan Singh <gurchetansingh@chromium.org>
Date: Mon, 2 Dec 2019 17:36:27 -0800
Subject: [PATCH] udmabuf: implement begin_cpu_access/end_cpu_access
hooks
Commit 284562e1f34874e267d4f499362c3816f8f6bc3f upstream.
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>
Link: http://patchwork.freedesktop.org/patch/msgid/20191203013627.85991-4-gurchetansingh@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
drivers/dma-buf/udmabuf.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -18,6 +18,7 @@ static const size_t size_limit_mb = 64;
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
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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