linux-kernel - [PATCH resend] swiotlb: ensure that page-sized mappings are page-aligned

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Date:   Wed, 11 Jan 2017 21:56:31 +0300
From:   Nikita Yushchenko <nikita.yoush@...entembedded.com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     linux-kernel@...r.kernel.org,
        Artemi Ivanov <artemi.ivanov@...entembedded.com>,
        Christoph Hellwig <hch@....de>, linux-nvme@...ts.infradead.org,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>
Subject: [PATCH resend] swiotlb: ensure that page-sized mappings are page-aligned

Some drivers do depend on page mappings to be page aligned.

Swiotlb already enforces such alignment for mappings greater than page,
extend that to page-sized mappings as well.

Without this fix, nvme hits BUG() in nvme_setup_prps(), because that routine
assumes page-aligned mappings.

Signed-off-by: Nikita Yushchenko <nikita.yoush@...entembedded.com>
---
 lib/swiotlb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 975b8fc..a8d74a7 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -483,11 +483,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 
 	/*
-	 * For mappings greater than a page, we limit the stride (and
-	 * hence alignment) to a page size.
+	 * For mappings greater than or equal to a page, we limit the stride
+	 * (and hence alignment) to a page size.
 	 */
 	nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
-	if (size > PAGE_SIZE)
+	if (size >= PAGE_SIZE)
 		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 	else
 		stride = 1;
-- 
2.1.4