iommu/dma: add support for DMA_ATTR_REQUIRE_COHERENT attribute

Add support for the DMA_ATTR_REQUIRE_COHERENT attribute to the exported
functions. This attribute indicates that the SWIOTLB path must not be
used and that no sync operations should be performed.

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-v3-6-1dde90a7f08b@nvidia.com

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 5dac64be61bb272a2b93f12f3e6d287b0164ed53..94d5141696424df226c461e2c05a5eae89e27c19 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1211,7 +1211,7 @@ dma_addr_t iommu_dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
         */
        if (dev_use_swiotlb(dev, size, dir) &&
            iova_unaligned(iovad, phys, size)) {
-               if (attrs & DMA_ATTR_MMIO)
+               if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
                        return DMA_MAPPING_ERROR;
 
                phys = iommu_dma_map_swiotlb(dev, phys, size, dir, attrs);
@@ -1223,7 +1223,8 @@ dma_addr_t iommu_dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
                arch_sync_dma_for_device(phys, size, dir);
 
        iova = __iommu_dma_map(dev, phys, size, prot, dma_mask);
-       if (iova == DMA_MAPPING_ERROR && !(attrs & DMA_ATTR_MMIO))
+       if (iova == DMA_MAPPING_ERROR &&
+           !(attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)))
                swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
        return iova;
 }
@@ -1233,7 +1234,7 @@ void iommu_dma_unmap_phys(struct device *dev, dma_addr_t dma_handle,
 {
        phys_addr_t phys;
 
-       if (attrs & DMA_ATTR_MMIO) {
+       if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)) {
                __iommu_dma_unmap(dev, dma_handle, size);
                return;
        }
@@ -1945,9 +1946,21 @@ int dma_iova_link(struct device *dev, struct dma_iova_state *state,
        if (WARN_ON_ONCE(iova_start_pad && offset > 0))
                return -EIO;
 
+       /*
+        * DMA_IOVA_USE_SWIOTLB is set on state after some entry
+        * took SWIOTLB path, which we were supposed to prevent
+        * for DMA_ATTR_REQUIRE_COHERENT attribute.
+        */
+       if (WARN_ON_ONCE((state->__size & DMA_IOVA_USE_SWIOTLB) &&
+                        (attrs & DMA_ATTR_REQUIRE_COHERENT)))
+               return -EOPNOTSUPP;
+
+       if (!dev_is_dma_coherent(dev) && (attrs & DMA_ATTR_REQUIRE_COHERENT))
+               return -EOPNOTSUPP;
+
        if (dev_use_swiotlb(dev, size, dir) &&
            iova_unaligned(iovad, phys, size)) {
-               if (attrs & DMA_ATTR_MMIO)
+               if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT))
                        return -EPERM;
 
                return iommu_dma_iova_link_swiotlb(dev, state, phys, offset,