From d93b3ac0edb85b1c1e8fe0a065c1e5045783e2f6 Mon Sep 17 00:00:00 2001 From: Antonios Motakis Date: Fri, 11 Oct 2013 10:40:46 -0600 Subject: VFIO: vfio_iommu_type1: fix bug caused by break in nested loop In vfio_iommu_type1.c there is a bug in vfio_dma_do_map, when checking that pages are not already mapped. Since the check is being done in a for loop nested within the main loop, breaking out of it does not create the intended behavior. If the underlying IOMMU driver returns a non-NULL value, this will be ignored and mapping the DMA range will be attempted anyway, leading to unpredictable behavior. This interracts badly with the ARM SMMU driver issue fixed in the patch that was submitted with the title: "[PATCH 2/2] ARM: SMMU: return NULL on error in arm_smmu_iova_to_phys" Both fixes are required in order to use the vfio_iommu_type1 driver with an ARM SMMU. This patch refactors the function slightly, in order to also make this kind of bug less likely. Signed-off-by: Antonios Motakis Signed-off-by: Alex Williamson --- drivers/vfio/vfio_iommu_type1.c | 40 +++++++++++++++++++++------------------- 1 file changed, 21 insertions(+), 19 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index a9807dea3887..4fb7a8f83c8a 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -545,6 +545,8 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, long npage; int ret = 0, prot = 0; uint64_t mask; + struct vfio_dma *dma = NULL; + unsigned long pfn; end = map->iova + map->size; @@ -587,8 +589,6 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, } for (iova = map->iova; iova < end; iova += size, vaddr += size) { - struct vfio_dma *dma = NULL; - unsigned long pfn; long i; /* Pin a contiguous chunk of memory */ @@ -597,16 +597,15 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, if (npage <= 0) { WARN_ON(!npage); ret = (int)npage; - break; + goto out; } /* Verify pages are not already mapped */ for (i = 0; i < npage; i++) { if (iommu_iova_to_phys(iommu->domain, iova + (i << PAGE_SHIFT))) { - vfio_unpin_pages(pfn, npage, prot, true); ret = -EBUSY; - break; + goto out_unpin; } } @@ -616,8 +615,7 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, if (ret) { if (ret != -EBUSY || map_try_harder(iommu, iova, pfn, npage, prot)) { - vfio_unpin_pages(pfn, npage, prot, true); - break; + goto out_unpin; } } @@ -672,9 +670,8 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, dma = kzalloc(sizeof(*dma), GFP_KERNEL); if (!dma) { iommu_unmap(iommu->domain, iova, size); - vfio_unpin_pages(pfn, npage, prot, true); ret = -ENOMEM; - break; + goto out_unpin; } dma->size = size; @@ -685,16 +682,21 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, } } - if (ret) { - struct vfio_dma *tmp; - iova = map->iova; - size = map->size; - while ((tmp = vfio_find_dma(iommu, iova, size))) { - int r = vfio_remove_dma_overlap(iommu, iova, - &size, tmp); - if (WARN_ON(r || !size)) - break; - } + WARN_ON(ret); + mutex_unlock(&iommu->lock); + return ret; + +out_unpin: + vfio_unpin_pages(pfn, npage, prot, true); + +out: + iova = map->iova; + size = map->size; + while ((dma = vfio_find_dma(iommu, iova, size))) { + int r = vfio_remove_dma_overlap(iommu, iova, + &size, dma); + if (WARN_ON(r || !size)) + break; } mutex_unlock(&iommu->lock); -- cgit v1.2.3