vfio/type1: unmap cleanup

Minor changes in vfio_dma_do_unmap to improve readability, which also
simplify the subsequent unmap-all patch.  No functional change.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio_iommu_type1.c

@@ -1074,34 +1074,28 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 {
 	struct vfio_dma *dma, *dma_last = NULL;
 	size_t unmapped = 0, pgsize;
-	int ret = 0, retries = 0;
+	int ret = -EINVAL, retries = 0;
 	unsigned long pgshift;
+	dma_addr_t iova = unmap->iova;
+	unsigned long size = unmap->size;
 
 	mutex_lock(&iommu->lock);
 
 	pgshift = __ffs(iommu->pgsize_bitmap);
 	pgsize = (size_t)1 << pgshift;
 
-	if (unmap->iova & (pgsize - 1)) {
-		ret = -EINVAL;
+	if (iova & (pgsize - 1))
 		goto unlock;
-	}
 
-	if (!unmap->size || unmap->size & (pgsize - 1)) {
-		ret = -EINVAL;
+	if (!size || size & (pgsize - 1))
 		goto unlock;
-	}
 
-	if (unmap->iova + unmap->size - 1 < unmap->iova ||
-	    unmap->size > SIZE_MAX) {
-		ret = -EINVAL;
+	if (iova + size - 1 < iova || size > SIZE_MAX)
 		goto unlock;
-	}
 
 	/* When dirty tracking is enabled, allow only min supported pgsize */
 	if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
 	    (!iommu->dirty_page_tracking || (bitmap->pgsize != pgsize))) {
-		ret = -EINVAL;
 		goto unlock;
 	}
 
@@ -1139,20 +1133,18 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 	 * mappings within the range.
 	 */
 	if (iommu->v2) {
-		dma = vfio_find_dma(iommu, unmap->iova, 1);
-		if (dma && dma->iova != unmap->iova) {
-			ret = -EINVAL;
+		dma = vfio_find_dma(iommu, iova, 1);
+		if (dma && dma->iova != iova)
 			goto unlock;
-		}
-		dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0);
-		if (dma && dma->iova + dma->size != unmap->iova + unmap->size) {
-			ret = -EINVAL;
+
+		dma = vfio_find_dma(iommu, iova + size - 1, 0);
+		if (dma && dma->iova + dma->size != iova + size)
 			goto unlock;
-		}
 	}
 
-	while ((dma = vfio_find_dma(iommu, unmap->iova, unmap->size))) {
-		if (!iommu->v2 && unmap->iova > dma->iova)
+	ret = 0;
+	while ((dma = vfio_find_dma(iommu, iova, size))) {
+		if (!iommu->v2 && iova > dma->iova)
 			break;
 		/*
 		 * Task with same address space who mapped this iova range is
@@ -1190,7 +1182,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 
 		if (unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) {
 			ret = update_user_bitmap(bitmap->data, iommu, dma,
-						 unmap->iova, pgsize);
+						 iova, pgsize);
 			if (ret)
 				break;
 		}