dma-mapping: reliably inform about DMA support for IOMMU

If the DMA IOMMU path is going to be used, the appropriate check should
return that DMA is supported.

Fixes: b5c58b2fdc42 ("dma-mapping: direct calls for dma-iommu")
Closes: https://lore.kernel.org/all/181e06ff-35a3-434f-b505-672f430bd1cb@notapiano
Reported-by: Nícolas F. R. A. Prado <nfraprado@collabora.com> #KernelCI
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 7550b5dc5e55df8fd65d48d41960f11f3fe45077..022d670f8cad296bc270eb02c8edb3e895f40f30 100644 (file)
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -843,6 +843,9 @@ static int dma_supported(struct device *dev, u64 mask)
 
        if (WARN_ON(ops && use_dma_iommu(dev)))
                return false;
+
+       if (use_dma_iommu(dev))
+               return true;
        /*
         * ->dma_supported sets the bypass flag, so we must always call
         * into the method here unless the device is truly direct mapped.