[PATCH 3.16 182/306] net/mlx5: Avoid passing dma address 0 to firmware

[Ben Hutchings]

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Noa Osherovich <noaos@xxxxxxxxxxxx>

commit 6b276190c50a12511d889d9079ffb901ff94a822 upstream.

Currently the firmware can't work with a page with dma address 0.
Passing such an address to the firmware will cause the give_pages
command to fail.

To avoid this, in case we get a 0 dma address of a page from the
dma engine, we avoid passing it to FW by remapping to get an address
other than 0.

Fixes: bf0bf77f6519 ('mlx5: Support communicating arbitrary host...')
Signed-off-by: Noa Osherovich <noaos@xxxxxxxxxxxx>
Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 .../net/ethernet/mellanox/mlx5/core/pagealloc.c    | 26 +++++++++++++++-------
 1 file changed, 18 insertions(+), 8 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
@@ -243,6 +243,7 @@ static void free_4k(struct mlx5_core_dev
 static int alloc_system_page(struct mlx5_core_dev *dev, u16 func_id)
 {
 	struct page *page;
+	u64 zero_addr = 1;
 	u64 addr;
 	int err;
 
@@ -251,26 +252,35 @@ static int alloc_system_page(struct mlx5
 		mlx5_core_warn(dev, "failed to allocate page\n");
 		return -ENOMEM;
 	}
+map:
 	addr = dma_map_page(&dev->pdev->dev, page, 0,
 			    PAGE_SIZE, DMA_BIDIRECTIONAL);
 	if (dma_mapping_error(&dev->pdev->dev, addr)) {
 		mlx5_core_warn(dev, "failed dma mapping page\n");
 		err = -ENOMEM;
-		goto out_alloc;
+		goto err_mapping;
 	}
+
+	/* Firmware doesn't support page with physical address 0 */
+	if (addr == 0) {
+		zero_addr = addr;
+		goto map;
+	}
+
 	err = insert_page(dev, addr, page, func_id);
 	if (err) {
 		mlx5_core_err(dev, "failed to track allocated page\n");
-		goto out_mapping;
+		dma_unmap_page(&dev->pdev->dev, addr, PAGE_SIZE,
+			       DMA_BIDIRECTIONAL);
 	}
 
-	return 0;
-
-out_mapping:
-	dma_unmap_page(&dev->pdev->dev, addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+err_mapping:
+	if (err)
+		__free_page(page);
 
-out_alloc:
-	__free_page(page);
+	if (zero_addr == 0)
+		dma_unmap_page(&dev->pdev->dev, zero_addr, PAGE_SIZE,
+			       DMA_BIDIRECTIONAL);
 
 	return err;
 }