iommu/dma: Use the gfp parameter in __iommu_dma_alloc_noncontiguous()

This function does an allocation of a buffer to return to the caller and
then goes on to allocate some internal memory, eg the scatterlist and
IOPTEs.

Instead of hard wiring GFP_KERNEL and a wrong GFP_ATOMIC, continue to use
the passed in gfp flags for all of the allocations. Clear the zone and
policy bits that are only relevant for the buffer allocation before
re-using them for internal allocations.

Auditing says this is never called from an atomic context, so the
GFP_ATOMIC is the incorrect flag.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v3-76b587fe28df+6e3-iommu_map_gfp_jgg@nvidia.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/dma-iommu.c

@@ -822,7 +822,14 @@ static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,
 	if (!iova)
 		goto out_free_pages;
 
-	if (sg_alloc_table_from_pages(sgt, pages, count, 0, size, GFP_KERNEL))
+	/*
+	 * Remove the zone/policy flags from the GFP - these are applied to the
+	 * __iommu_dma_alloc_pages() but are not used for the supporting
+	 * internal allocations that follow.
+	 */
+	gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM | __GFP_COMP);
+
+	if (sg_alloc_table_from_pages(sgt, pages, count, 0, size, gfp))
 		goto out_free_iova;
 
 	if (!(ioprot & IOMMU_CACHE)) {
@@ -834,7 +841,7 @@ static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,
 	}
 
 	ret = iommu_map_sg(domain, iova, sgt->sgl, sgt->orig_nents, ioprot,
-			   GFP_ATOMIC);
+			   gfp);
 	if (ret < 0 || ret < size)
 		goto out_free_sg;