linux-kernel - [PATCH v2 2/2] vfio iommu: Fix size argument to vfio_find_dma() in pin_pages/unpin

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Message-ID: <1481048892-29881-1-git-send-email-kwankhede@nvidia.com>
Date:   Tue, 6 Dec 2016 23:58:12 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     <alex.williamson@...hat.com>, <pbonzini@...hat.com>,
        <kraxel@...hat.com>, <cjia@...dia.com>
CC:     <qemu-devel@...gnu.org>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Kirti Wankhede <kwankhede@...dia.com>
Subject: [PATCH v2 2/2] vfio iommu: Fix size argument to vfio_find_dma() in pin_pages/unpin_pages

Passing zero for the size to vfio_find_dma() isn't compatible with
matching the start address of an existing vfio_dma. Doing so triggers a
corner case. In vfio_find_dma(), when the start address is equal to
dma->iova and size is 0, check for the end of search range makes it to
take wrong side of RB-tree. That fails the search even though the address
is present in mapped dma ranges.
In functions pin_pages and unpin_pages, the iova which is being searched
is base address of page to be pinned or unpinned. So here size should be
set to PAGE_SIZE, as argument to vfio_find_dma().

Signed-off-by: Kirti Wankhede <kwankhede@...dia.com>
Signed-off-by: Neo Jia <cjia@...dia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8e9e94ccb2ff..023fba7b8d5a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -581,7 +581,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 		struct vfio_pfn *vpfn;
 
 		iova = user_pfn[i] << PAGE_SHIFT;
-		dma = vfio_find_dma(iommu, iova, 0);
+		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
 		if (!dma) {
 			ret = -EINVAL;
 			goto pin_unwind;
@@ -622,7 +622,7 @@ pin_unwind:
 		dma_addr_t iova;
 
 		iova = user_pfn[j] << PAGE_SHIFT;
-		dma = vfio_find_dma(iommu, iova, 0);
+		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
 		vfio_unpin_page_external(dma, iova, do_accounting);
 		phys_pfn[j] = 0;
 	}
@@ -659,7 +659,7 @@ static int vfio_iommu_type1_unpin_pages(void *iommu_data,
 		dma_addr_t iova;
 
 		iova = user_pfn[i] << PAGE_SHIFT;
-		dma = vfio_find_dma(iommu, iova, 0);
+		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
 		if (!dma)
 			goto unpin_exit;
 		vfio_unpin_page_external(dma, iova, do_accounting);
-- 
2.7.0