vfio/type1: massage unmap iteration

Modify the iteration in vfio_dma_do_unmap so it does not depend on deletion
of each dma entry.  Add a variant of vfio_find_dma that returns the entry
with the lowest iova in the search range to initialize the iteration.  No
externally visible change, but this behavior is needed in the subsequent
update-vaddr patch.

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>

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5b388e5..ce97eda 100644 (file)
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -173,6 +173,31 @@ static struct vfio_dma *vfio_find_dma(struct vfio_iommu *iommu,
        return NULL;
 }
 
+static struct rb_node *vfio_find_dma_first_node(struct vfio_iommu *iommu,
+                                               dma_addr_t start, size_t size)
+{
+       struct rb_node *res = NULL;
+       struct rb_node *node = iommu->dma_list.rb_node;
+       struct vfio_dma *dma_res = NULL;
+
+       while (node) {
+               struct vfio_dma *dma = rb_entry(node, struct vfio_dma, node);
+
+               if (start < dma->iova + dma->size) {
+                       res = node;
+                       dma_res = dma;
+                       if (start >= dma->iova)
+                               break;
+                       node = node->rb_left;
+               } else {
+                       node = node->rb_right;
+               }
+       }
+       if (res && size && dma_res->iova >= start + size)
+               res = NULL;
+       return res;
+}
+
 static void vfio_link_dma(struct vfio_iommu *iommu, struct vfio_dma *new)
 {
        struct rb_node **link = &iommu->dma_list.rb_node, *parent = NULL;
@@ -1079,6 +1104,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
        dma_addr_t iova = unmap->iova;
        unsigned long size = unmap->size;
        bool unmap_all = unmap->flags & VFIO_DMA_UNMAP_FLAG_ALL;
+       struct rb_node *n;
 
        mutex_lock(&iommu->lock);
 
@@ -1149,7 +1175,13 @@ again:
        }
 
        ret = 0;
-       while ((dma = vfio_find_dma(iommu, iova, size))) {
+       n = vfio_find_dma_first_node(iommu, iova, size);
+
+       while (n) {
+               dma = rb_entry(n, struct vfio_dma, node);
+               if (dma->iova >= iova + size)
+                       break;
+
                if (!iommu->v2 && iova > dma->iova)
                        break;
                /*
@@ -1194,6 +1226,7 @@ again:
                }
 
                unmapped += dma->size;
+               n = rb_next(n);
                vfio_remove_dma(iommu, dma);
        }