linux-kernel - [PATCH] vfio/type1: fix dirty bitmap calculation in vfio_dma

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Message-Id: <20200915003251.14343-1-yan.y.zhao@intel.com>
Date:   Tue, 15 Sep 2020 08:32:51 +0800
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     alex.williamson@...hat.com, cohuck@...hat.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yan Zhao <yan.y.zhao@...el.com>
Subject: [PATCH] vfio/type1: fix dirty bitmap calculation in vfio_dma_rw

the count of dirtied pages is not only determined by count of copied
pages, but also by the start offset.

e.g. if offset = PAGE_SIZE - 1, and *copied=2, the dirty pages count is
2, instead of 0.

Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty
pages tracking")

Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 drivers/vfio/vfio_iommu_type1.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5fbf0c1f7433..d0438388feeb 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2933,7 +2933,8 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu,
 			 * size
 			 */
 			bitmap_set(dma->bitmap, offset >> pgshift,
-				   *copied >> pgshift);
+				   ((offset + *copied - 1) >> pgshift) -
+				   (offset >> pgshift) + 1);
 		}
 	} else
 		*copied = copy_from_user(data, (void __user *)vaddr,
-- 
2.17.1