1 files changed, 39 insertions, 48 deletions

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index 4440e626b797..550980dd3b0b 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/dma-buf.h>
+#include <linux/dma-direct.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>
@@ -22,7 +23,7 @@
 #include "gntdev-common.h"
 #include "gntdev-dmabuf.h"
 
-MODULE_IMPORT_NS(DMA_BUF);
+MODULE_IMPORT_NS("DMA_BUF");
 
 struct gntdev_dmabuf {
 	struct gntdev_dmabuf_priv *priv;
@@ -50,7 +51,7 @@ struct gntdev_dmabuf {
 
 	/* Number of pages this buffer has. */
 	int nr_pages;
-	/* Pages of this buffer. */
+	/* Pages of this buffer (only for dma-buf export). */
 	struct page **pages;
 };
 
@@ -356,8 +357,11 @@ struct gntdev_dmabuf_export_args {
 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 {
 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
-	struct gntdev_dmabuf *gntdev_dmabuf;
-	int ret;
+	struct gntdev_dmabuf *gntdev_dmabuf __free(kfree) = NULL;
+	CLASS(get_unused_fd, ret)(O_CLOEXEC);
+
+	if (ret < 0)
+		return ret;
 
 	gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 	if (!gntdev_dmabuf)
@@ -382,32 +386,21 @@ static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 	exp_info.priv = gntdev_dmabuf;
 
 	gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
-	if (IS_ERR(gntdev_dmabuf->dmabuf)) {
-		ret = PTR_ERR(gntdev_dmabuf->dmabuf);
-		gntdev_dmabuf->dmabuf = NULL;
-		goto fail;
-	}
-
-	ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
-	if (ret < 0)
-		goto fail;
+	if (IS_ERR(gntdev_dmabuf->dmabuf))
+		return PTR_ERR(gntdev_dmabuf->dmabuf);
 
 	gntdev_dmabuf->fd = ret;
 	args->fd = ret;
 
 	pr_debug("Exporting DMA buffer with fd %d\n", ret);
 
+	get_file(gntdev_dmabuf->priv->filp);
 	mutex_lock(&args->dmabuf_priv->lock);
 	list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
 	mutex_unlock(&args->dmabuf_priv->lock);
-	get_file(gntdev_dmabuf->priv->filp);
-	return 0;
 
-fail:
-	if (gntdev_dmabuf->dmabuf)
-		dma_buf_put(gntdev_dmabuf->dmabuf);
-	kfree(gntdev_dmabuf);
-	return ret;
+	fd_install(take_fd(ret), no_free_ptr(gntdev_dmabuf)->dmabuf->file);
+	return 0;
 }
 
 static struct gntdev_grant_map *
@@ -484,7 +477,7 @@ out:
 /* DMA buffer import support. */
 
 static int
-dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
+dmabuf_imp_grant_foreign_access(unsigned long *gfns, u32 *refs,
 				int count, int domid)
 {
 	grant_ref_t priv_gref_head;
@@ -507,7 +500,7 @@ dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
 		}
 
 		gnttab_grant_foreign_access_ref(cur_ref, domid,
-						xen_page_to_gfn(pages[i]), 0);
+						gfns[i], 0);
 		refs[i] = cur_ref;
 	}
 
@@ -529,7 +522,6 @@ static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 
 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
 {
-	kfree(gntdev_dmabuf->pages);
 	kfree(gntdev_dmabuf->u.imp.refs);
 	kfree(gntdev_dmabuf);
 }
@@ -549,12 +541,6 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 	if (!gntdev_dmabuf->u.imp.refs)
 		goto fail;
 
-	gntdev_dmabuf->pages = kcalloc(count,
-				       sizeof(gntdev_dmabuf->pages[0]),
-				       GFP_KERNEL);
-	if (!gntdev_dmabuf->pages)
-		goto fail;
-
 	gntdev_dmabuf->nr_pages = count;
 
 	for (i = 0; i < count; i++)
@@ -576,7 +562,8 @@ dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 	struct dma_buf *dma_buf;
 	struct dma_buf_attachment *attach;
 	struct sg_table *sgt;
-	struct sg_page_iter sg_iter;
+	struct sg_dma_page_iter sg_iter;
+	unsigned long *gfns;
 	int i;
 
 	dma_buf = dma_buf_get(fd);
@@ -624,26 +611,31 @@ dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 
 	gntdev_dmabuf->u.imp.sgt = sgt;
 
-	/* Now convert sgt to array of pages and check for page validity. */
+	gfns = kcalloc(count, sizeof(*gfns), GFP_KERNEL);
+	if (!gfns) {
+		ret = ERR_PTR(-ENOMEM);
+		goto fail_unmap;
+	}
+
+	/*
+	 * Now convert sgt to array of gfns without accessing underlying pages.
+	 * It is not allowed to access the underlying struct page of an sg table
+	 * exported by DMA-buf, but since we deal with special Xen dma device here
+	 * (not a normal physical one) look at the dma addresses in the sg table
+	 * and then calculate gfns directly from them.
+	 */
 	i = 0;
-	for_each_sgtable_page(sgt, &sg_iter, 0) {
-		struct page *page = sg_page_iter_page(&sg_iter);
-		/*
-		 * Check if page is valid: this can happen if we are given
-		 * a page from VRAM or other resources which are not backed
-		 * by a struct page.
-		 */
-		if (!pfn_valid(page_to_pfn(page))) {
-			ret = ERR_PTR(-EINVAL);
-			goto fail_unmap;
-		}
+	for_each_sgtable_dma_page(sgt, &sg_iter, 0) {
+		dma_addr_t addr = sg_page_iter_dma_address(&sg_iter);
+		unsigned long pfn = bfn_to_pfn(XEN_PFN_DOWN(dma_to_phys(dev, addr)));
 
-		gntdev_dmabuf->pages[i++] = page;
+		gfns[i++] = pfn_to_gfn(pfn);
 	}
 
-	ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
+	ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gfns,
 						      gntdev_dmabuf->u.imp.refs,
 						      count, domid));
+	kfree(gfns);
 	if (IS_ERR(ret))
 		goto fail_end_access;
 
@@ -728,16 +720,15 @@ static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
 
 /* DMA buffer IOCTL support. */
 
-long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
+long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
 				       struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 {
 	struct ioctl_gntdev_dmabuf_exp_from_refs op;
 	u32 *refs;
 	long ret;
 
-	if (use_ptemod) {
-		pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
-			 use_ptemod);
+	if (xen_pv_domain()) {
+		pr_debug("Cannot provide dma-buf in a PV domain\n");
 		return -EINVAL;
 	}