Subject: [PATCH v4 13/13] x86/amd-gart: preserve the direct DMA address until GART mapping succeeds

From: "Aneesh Kumar K.V (Arm)" <[email-masked]>
Date: Tue, 12 May 2026 14:34:08 +0530

gart_alloc_coherent() first allocates memory through dma_direct_alloc(),
which returns a direct-mapped DMA address in dma_addr. When force_iommu is
enabled, the buffer is then remapped.

Do not overwrite dma_addr before dma_map_area() has succeeded. Keep the
dma_map_area result in a temporary variable so the direct DMA address
remains available for dma_direct_free() on the error path.

Signed-off-by: Aneesh Kumar K.V (Arm) <[email-masked]>
---
 arch/x86/kernel/amd_gart_64.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index b5f1f031d45b..a109649c5649 100644
--- a/arch/x86/kernel/amd_gart_64.c
+++ b/arch/x86/kernel/amd_gart_64.c
@@ -467,18 +467,20 @@ gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
 		    gfp_t flag, unsigned long attrs)
 {
 	void *vaddr;
+	dma_addr_t dma_map_addr;
 
 	vaddr = dma_direct_alloc(dev, size, dma_addr, flag, attrs);
 	if (!vaddr ||
 	    !force_iommu || dev->coherent_dma_mask <= DMA_BIT_MASK(24))
 		return vaddr;
 
-	*dma_addr = dma_map_area(dev, virt_to_phys(vaddr), size,
-				 DMA_BIDIRECTIONAL,
-				 (1UL << get_order(size)) - 1, attrs);
+	dma_map_addr = dma_map_area(dev, virt_to_phys(vaddr), size,
+				     DMA_BIDIRECTIONAL,
+				     (1UL << get_order(size)) - 1, attrs);
 	flush_gart();
-	if (unlikely(*dma_addr == DMA_MAPPING_ERROR))
+	if (unlikely(dma_map_addr == DMA_MAPPING_ERROR))
 		goto out_free;
+	*dma_addr = dma_map_addr;
 	return vaddr;
 out_free:
 	dma_direct_free(dev, size, vaddr, *dma_addr, attrs);
-- 
2.43.0