linux-kernel - [PATCH v2] dma-remap: Align the size in dma_common_*

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Date:   Tue, 23 Jun 2020 14:07:55 +0200
From:   Eric Auger <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, eric.auger@...hat.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        hch@....de
Cc:     m.szyprowski@...sung.com, robin.murphy@....com,
        peterz@...radead.org, akpm@...ux-foundation.org,
        jean-philippe@...aro.org, bbhushan2@...vell.com
Subject: [PATCH v2] dma-remap: Align the size in dma_common_*_remap()

Running a guest with a virtio-iommu protecting virtio devices
is broken since commit 515e5b6d90d4 ("dma-mapping: use vmap insted
of reimplementing it"). Before the conversion, the size was
page aligned in __get_vm_area_node(). Doing so fixes the
regression.

Fixes: 515e5b6d90d4 ("dma-mapping: use vmap insted of reimplementing it")
Signed-off-by: Eric Auger <eric.auger@...hat.com>

---

v1 -> v2:
- fix line over 80 characters
---
 kernel/dma/remap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
index e739a6eea6e7..78b23f089cf1 100644
--- a/kernel/dma/remap.c
+++ b/kernel/dma/remap.c
@@ -24,7 +24,8 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
 {
 	void *vaddr;
 
-	vaddr = vmap(pages, size >> PAGE_SHIFT, VM_DMA_COHERENT, prot);
+	vaddr = vmap(pages, PAGE_ALIGN(size) >> PAGE_SHIFT,
+		     VM_DMA_COHERENT, prot);
 	if (vaddr)
 		find_vm_area(vaddr)->pages = pages;
 	return vaddr;
@@ -37,7 +38,7 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
 void *dma_common_contiguous_remap(struct page *page, size_t size,
 			pgprot_t prot, const void *caller)
 {
-	int count = size >> PAGE_SHIFT;
+	int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	struct page **pages;
 	void *vaddr;
 	int i;
-- 
2.20.1