xen: swiotlb: Use swiotlb bouncing if kmalloc allocation demands it

commit cd9c058 upstream.

Xen swiotlb support was missed when the patch set starting with
4ab5f8e ("mm/slab: decouple ARCH_KMALLOC_MINALIGN from
ARCH_DMA_MINALIGN") was merged.

When running Xen on iMX8QXP, a SoC without IOMMU, the effect was that USB
transfers ended up corrupted when there was more than one URB inflight at
the same time.

Add a call to dma_kmalloc_needs_bounce() to make sure that allocations too
small for DMA get bounced via swiotlb.

Closes: https://lore.kernel.org/linux-usb/[email protected]/
Fixes: 4ab5f8e ("mm/slab: decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN")
Cc: [email protected] # v6.5+
Signed-off-by: John Ernberg <[email protected]>
Reviewed-by: Stefano Stabellini <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: johnernberg

drivers/xen/swiotlb-xen.c

@@ -217,6 +217,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 	 * buffering it.
 	 */
 	if (dma_capable(dev, dev_addr, size, true) &&
+	    !dma_kmalloc_needs_bounce(dev, size, dir) &&
 	    !range_straddles_page_boundary(phys, size) &&
 		!xen_arch_need_swiotlb(dev, phys, dev_addr) &&
 		!is_swiotlb_force_bounce(dev))