1 files changed, 42 insertions, 35 deletions

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8a2be4e40f22..98231d10890c 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -370,6 +370,9 @@ static int vfio_remove_dma_overlap(struct vfio_iommu *iommu, dma_addr_t start,
         struct vfio_dma *split;
         int ret;
 
+        if (!*size)
+                return 0;
+
         /*
          * Existing dma region is completely covered, unmap all.  This is
          * the likely case since userspace tends to map and unmap buffers
@@ -411,7 +414,9 @@ static int vfio_remove_dma_overlap(struct vfio_iommu *iommu, dma_addr_t start,
                         dma->vaddr += overlap;
                         dma->size -= overlap;
                         vfio_insert_dma(iommu, dma);
-                }
+                } else
+                        kfree(dma);
+
                 *size = overlap;
                 return 0;
         }
@@ -425,48 +430,41 @@ static int vfio_remove_dma_overlap(struct vfio_iommu *iommu, dma_addr_t start,
                 if (ret)
                         return ret;
 
-                /*
-                 * We may have unmapped the entire vfio_dma if the user is
-                 * trying to unmap a sub-region of what was originally
-                 * mapped.  If anything left, we can resize in place since
-                 * iova is unchanged.
-                 */
-                if (overlap < dma->size)
-                        dma->size -= overlap;
-                else
-                        vfio_remove_dma(iommu, dma);
-
+                dma->size -= overlap;
                 *size = overlap;
                 return 0;
         }
 
         /* Split existing */
+        split = kzalloc(sizeof(*split), GFP_KERNEL);
+        if (!split)
+                return -ENOMEM;
+
         offset = start - dma->iova;
 
         ret = vfio_unmap_unpin(iommu, dma, start, size);
         if (ret)
                 return ret;
 
-        WARN_ON(!*size);
+        if (!*size) {
+                kfree(split);
+                return -EINVAL;
+        }
+
         tmp = dma->size;
 
-        /*
-         * Resize the lower vfio_dma in place, insert new for remaining
-         * upper segment.
-         */
+        /* Resize the lower vfio_dma in place, before the below insert */
         dma->size = offset;
 
-        if (offset + *size < tmp) {
-                split = kzalloc(sizeof(*split), GFP_KERNEL);
-                if (!split)
-                        return -ENOMEM;
-
+        /* Insert new for remainder, assuming it didn't all get unmapped */
+        if (likely(offset + *size < tmp)) {
                 split->size = tmp - offset - *size;
                 split->iova = dma->iova + offset + *size;
                 split->vaddr = dma->vaddr + offset + *size;
                 split->prot = dma->prot;
                 vfio_insert_dma(iommu, split);
-        }
+        } else
+                kfree(split);
 
         return 0;
 }
@@ -483,7 +481,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 
         if (unmap->iova & mask)
                 return -EINVAL;
-        if (unmap->size & mask)
+        if (!unmap->size || unmap->size & mask)
                 return -EINVAL;
 
         WARN_ON(mask & PAGE_MASK);
@@ -493,7 +491,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
         while ((dma = vfio_find_dma(iommu, unmap->iova, unmap->size))) {
                 size = unmap->size;
                 ret = vfio_remove_dma_overlap(iommu, unmap->iova, &size, dma);
-                if (ret)
+                if (ret || !size)
                         break;
                 unmapped += size;
         }
@@ -635,7 +633,6 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
                         if (tmp && tmp->prot == prot &&
                             tmp->vaddr + tmp->size == vaddr) {
                                 tmp->size += size;
-
                                 iova = tmp->iova;
                                 size = tmp->size;
                                 vaddr = tmp->vaddr;
@@ -643,19 +640,28 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
                         }
                 }
 
-                /* Check if we abut a region above - nothing above ~0 + 1 */
+                /*
+                 * Check if we abut a region above - nothing above ~0 + 1.
+                 * If we abut above and below, remove and free.  If only
+                 * abut above, remove, modify, reinsert.
+                 */
                 if (likely(iova + size)) {
                         struct vfio_dma *tmp;
-
                         tmp = vfio_find_dma(iommu, iova + size, 1);
                         if (tmp && tmp->prot == prot &&
                             tmp->vaddr == vaddr + size) {
                                 vfio_remove_dma(iommu, tmp);
-                                if (dma)
+                                if (dma) {
                                         dma->size += tmp->size;
-                                else
+                                        kfree(tmp);
+                                } else {
                                         size += tmp->size;
-                                kfree(tmp);
+                                        tmp->size = size;
+                                        tmp->iova = iova;
+                                        tmp->vaddr = vaddr;
+                                        vfio_insert_dma(iommu, tmp);
+                                        dma = tmp;
+                                }
                         }
                 }
 
@@ -681,11 +687,10 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
                 iova = map->iova;
                 size = map->size;
                 while ((tmp = vfio_find_dma(iommu, iova, size))) {
-                        if (vfio_remove_dma_overlap(iommu, iova, &size, tmp)) {
-                                pr_warn("%s: Error rolling back failed map\n",
-                                        __func__);
+                        int r = vfio_remove_dma_overlap(iommu, iova,
+                                                        &size, tmp);
+                        if (WARN_ON(r || !size))
                                 break;
-                        }
                 }
         }