[Qemu-devel] [PATCH v2 2/2] vfio iommu: Fix size argument to vfio_find_dma() in pin_pages/unpin_pages

[Kirti Wankhede]

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 <address@hidden>
Signed-off-by: Neo Jia <address@hidden>
---
 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