From 2536617f20ddc7c2f4cef59b549aa45d166b03b1 Mon Sep 17 00:00:00 2001 From: Leon Romanovsky Date: Mon, 16 Mar 2026 21:06:49 +0200 Subject: [PATCH] dma-direct: prevent SWIOTLB path when DMA_ATTR_REQUIRE_COHERENT is set DMA_ATTR_REQUIRE_COHERENT indicates that SWIOTLB must not be used. Ensure the SWIOTLB path is declined whenever the DMA direct path is selected. Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20260316-dma-debug-overlap-v3-5-1dde90a7f08b@nvidia.com --- kernel/dma/direct.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h index e89f175e9c2d..6184ff303f08 100644 --- a/kernel/dma/direct.h +++ b/kernel/dma/direct.h @@ -84,7 +84,7 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev, dma_addr_t dma_addr; if (is_swiotlb_force_bounce(dev)) { - if (attrs & DMA_ATTR_MMIO) + if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)) return DMA_MAPPING_ERROR; return swiotlb_map(dev, phys, size, dir, attrs); @@ -98,7 +98,8 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev, dma_addr = phys_to_dma(dev, phys); if (unlikely(!dma_capable(dev, dma_addr, size, true)) || dma_kmalloc_needs_bounce(dev, size, dir)) { - if (is_swiotlb_active(dev)) + if (is_swiotlb_active(dev) && + !(attrs & DMA_ATTR_REQUIRE_COHERENT)) return swiotlb_map(dev, phys, size, dir, attrs); goto err_overflow; @@ -123,7 +124,7 @@ static inline void dma_direct_unmap_phys(struct device *dev, dma_addr_t addr, { phys_addr_t phys; - if (attrs & DMA_ATTR_MMIO) + if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)) /* nothing to do: uncached and no swiotlb */ return;