[PATCH RFC 4/9] mm: kmsan: Add support for DMA mapping bio_vec arrays

[Chuck Lever <cel@xxxxxxxxxx>]

From: Chuck Lever <chuck.lever@xxxxxxxxxx>

Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: kasan-dev@xxxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: iommu@xxxxxxxxxxxxxxx
Cc: linux-rdma@xxxxxxxxxxxxxxx
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 include/linux/kmsan.h |   20 ++++++++++++++++++++
 mm/kmsan/hooks.c      |   13 +++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h
index e0c23a32cdf0..36c581a18b30 100644
--- a/include/linux/kmsan.h
+++ b/include/linux/kmsan.h
@@ -18,6 +18,7 @@ struct page;
 struct kmem_cache;
 struct task_struct;
 struct scatterlist;
+struct bio_vec;
 struct urb;
 
 #ifdef CONFIG_KMSAN
@@ -209,6 +210,20 @@ void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
 void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
 			 enum dma_data_direction dir);
 
+/**
+ * kmsan_handle_dma_bvecs() - Handle a DMA transfer using bio_vec array.
+ * @bvecs: bio_vec array holding DMA buffers.
+ * @nents: number of scatterlist entries.
+ * @dir:   one of possible dma_data_direction values.
+ *
+ * Depending on @direction, KMSAN:
+ * * checks the buffers in the bio_vec array, if they are copied to device;
+ * * initializes the buffers, if they are copied from device;
+ * * does both, if this is a DMA_BIDIRECTIONAL transfer.
+ */
+void kmsan_handle_dma_bvecs(struct bio_vec *bv, int nents,
+			    enum dma_data_direction dir);
+
 /**
  * kmsan_handle_urb() - Handle a USB data transfer.
  * @urb:    struct urb pointer.
@@ -321,6 +336,11 @@ static inline void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
 {
 }
 
+static inline void kmsan_handle_dma_bvecs(struct bio_vec *bv, int nents,
+					  enum dma_data_direction dir)
+{
+}
+
 static inline void kmsan_handle_urb(const struct urb *urb, bool is_out)
 {
 }
diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 5d6e2dee5692..87846011c9bd 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -358,6 +358,19 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
 				 dir);
 }
 
+void kmsan_handle_dma_bvecs(struct bio_vec *bvecs, int nents,
+			    enum dma_data_direction dir)
+{
+	struct bio_vec *item;
+	int i;
+
+	for (i = 0; i < nents; i++) {
+		item = &bvecs[i];
+		kmsan_handle_dma(bv_page(item), item->bv_offset, item->bv_len,
+				 dir);
+	}
+}
+
 /* Functions from kmsan-checks.h follow. */
 void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
 {