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 <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260316-dma-debug-overlap-v3-5-1dde90a7f08b@nvidia.com

diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
index e89f175e9c2d0161e89a2c8b4a9b7eb57bec61d9..6184ff303f080932573532118d140e1741f19799 100644 (file)
--- 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;