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

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Message-Id: <1483443037-6972-1-git-send-email-nikita.yoush@cogentembedded.com>
Date:   Tue,  3 Jan 2017 14:30:37 +0300
From:   Nikita Yushchenko <nikita.yoush@...entembedded.com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     Artemi Ivanov <artemi.ivanov@...entembedded.com>,
        linux-kernel@...r.kernel.org,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>
Subject: [PATCH] swiotlb: ensure that page-sized mappings are page-aligned

Some drivers (e.g. nvme) 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.

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 cb1b54e..b0ee957 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -453,11 +453,11 @@ 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