From: Ivan Malov <ivan.malov@oktetlabs.ru>
Date: Tue, 28 Jun 2022 12:18:48 +0300
Subject: xsk: Clear page contiguity bit when unmapping pool
Patch-mainline: v5.19-rc6
Git-commit: 512d1999b8e94a5d43fba3afc73e774849674742
References: jsc#PED-1377

When a XSK pool gets mapped, xp_check_dma_contiguity() adds bit 0x1
to pages' DMA addresses that go in ascending order and at 4K stride.

The problem is that the bit does not get cleared before doing unmap.
As a result, a lot of warnings from iommu_dma_unmap_page() are seen
in dmesg, which indicates that lookups by iommu_iova_to_phys() fail.

Fixes: 2b43470add8c ("xsk: Introduce AF_XDP buffer allocation API")
Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20220628091848.534803-1-ivan.malov@oktetlabs.ru
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 net/xdp/xsk_buff_pool.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -332,6 +332,7 @@ static void __xp_dma_unmap(struct xsk_dm
 	for (i = 0; i < dma_map->dma_pages_cnt; i++) {
 		dma = &dma_map->dma_pages[i];
 		if (*dma) {
+			*dma &= ~XSK_NEXT_PG_CONTIG_MASK;
 			dma_unmap_page_attrs(dma_map->dev, *dma, PAGE_SIZE,
 					     DMA_BIDIRECTIONAL, attrs);
 			*dma = 0;