From: Mario Limonciello <mario.limonciello@amd.com>
Date: Mon, 4 Apr 2022 15:47:23 -0500
Subject: dma-iommu: Check that swiotlb is active before trying to use it
Git-commit: f316ba0a8814f4c91e80a435da3421baf0ddd24c
Patch-mainline: v5.19-rc1
References: bsc#1205701

If the IOMMU is in use and an untrusted device is connected to an external
facing port but the address requested isn't page aligned will cause the
kernel to attempt to use bounce buffers.

If for some reason the bounce buffers have not been allocated this is a
problem that should be made apparent to the user.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220404204723.9767-3-mario.limonciello@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/dma-iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 09f6e1c0f9c0..1ca85d37eeab 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -971,6 +971,11 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 		void *padding_start;
 		size_t padding_size, aligned_size;
 
+		if (!is_swiotlb_active(dev)) {
+			dev_warn_once(dev, "DMA bounce buffers are inactive, unable to map unaligned transaction.\n");
+			return DMA_MAPPING_ERROR;
+		}
+
 		aligned_size = iova_align(iovad, size);
 		phys = swiotlb_tbl_map_single(dev, phys, size, aligned_size,
 					      iova_mask(iovad), dir, attrs);