iommufd: Accept a DMABUF through IOMMU_IOAS_MAP_FILE

Finally call iopt_alloc_dmabuf_pages() if the user passed in a DMABUF
through IOMMU_IOAS_MAP_FILE. This makes the feature visible to userspace.

Link: https://patch.msgid.link/r/8-v2-b2c110338e3f+5c2-iommufd_dmabuf_jgg@nvidia.com
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

3 files changed, 41 insertions, 19 deletions

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index 0bf6ca77888c..44a0a7c79388 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -8,6 +8,7 @@
  * The datastructure uses the iopt_pages to optimize the storage of the PFNs
  * between the domains and xarray.
  */
+#include <linux/dma-buf.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/file.h>
@@ -484,19 +485,41 @@ int iopt_map_file_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt,
 			unsigned int flags)
 {
 	struct iopt_pages *pages;
-	struct file *file;
+	struct dma_buf *dmabuf;
+	unsigned long start_byte;
+	unsigned long last;
 
-	file = fget(fd);
-	if (!file)
-		return -EBADF;
+	if (!length)
+		return -EINVAL;
+	if (check_add_overflow(start, length - 1, &last))
+		return -EOVERFLOW;
+
+	start_byte = start - ALIGN_DOWN(start, PAGE_SIZE);
+	dmabuf = dma_buf_get(fd);
+	if (!IS_ERR(dmabuf)) {
+		pages = iopt_alloc_dmabuf_pages(ictx, dmabuf, start_byte, start,
+						length,
+						iommu_prot & IOMMU_WRITE);
+		if (IS_ERR(pages)) {
+			dma_buf_put(dmabuf);
+			return PTR_ERR(pages);
+		}
+	} else {
+		struct file *file;
+
+		file = fget(fd);
+		if (!file)
+			return -EBADF;
+
+		pages = iopt_alloc_file_pages(file, start_byte, start, length,
+					      iommu_prot & IOMMU_WRITE);
+		fput(file);
+		if (IS_ERR(pages))
+			return PTR_ERR(pages);
+	}
 
-	pages = iopt_alloc_file_pages(file, start, length,
-				      iommu_prot & IOMMU_WRITE);
-	fput(file);
-	if (IS_ERR(pages))
-		return PTR_ERR(pages);
 	return iopt_map_common(ictx, iopt, pages, iova, length,
-			       start - pages->start, iommu_prot, flags);
+			       start_byte, iommu_prot, flags);
 }
 
 struct iova_bitmap_fn_arg {
diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h
index 8f8d583e0243..14cd052fd320 100644
--- a/drivers/iommu/iommufd/io_pagetable.h
+++ b/drivers/iommu/iommufd/io_pagetable.h
@@ -265,7 +265,9 @@ static inline bool iopt_dmabuf_revoked(struct iopt_pages *pages)
 
 struct iopt_pages *iopt_alloc_user_pages(void __user *uptr,
 					 unsigned long length, bool writable);
-struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start,
+struct iopt_pages *iopt_alloc_file_pages(struct file *file,
+					 unsigned long start_byte,
+					 unsigned long start,
 					 unsigned long length, bool writable);
 struct iopt_pages *iopt_alloc_dmabuf_pages(struct iommufd_ctx *ictx,
 					   struct dma_buf *dmabuf,
diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c
index a2574eabb93d..c73456833d04 100644
--- a/drivers/iommu/iommufd/pages.c
+++ b/drivers/iommu/iommufd/pages.c
@@ -1413,22 +1413,19 @@ struct iopt_pages *iopt_alloc_user_pages(void __user *uptr,
 	return pages;
 }
 
-struct iopt_pages *iopt_alloc_file_pages(struct file *file, unsigned long start,
+struct iopt_pages *iopt_alloc_file_pages(struct file *file,
+					 unsigned long start_byte,
+					 unsigned long start,
 					 unsigned long length, bool writable)
 
 {
 	struct iopt_pages *pages;
-	unsigned long start_down = ALIGN_DOWN(start, PAGE_SIZE);
-	unsigned long end;
-
-	if (length && check_add_overflow(start, length - 1, &end))
-		return ERR_PTR(-EOVERFLOW);
 
-	pages = iopt_alloc_pages(start - start_down, length, writable);
+	pages = iopt_alloc_pages(start_byte, length, writable);
 	if (IS_ERR(pages))
 		return pages;
 	pages->file = get_file(file);
-	pages->start = start_down;
+	pages->start = start - start_byte;
 	pages->type = IOPT_ADDRESS_FILE;
 	return pages;
 }