vhost-iova-tree: Implement an IOVA-only tree

Creates and supports an IOVA-only tree to support a SVQ IOVA->HVA and
GPA->IOVA tree for host-only and guest-backed memory, respectively, in
the next patch.

The IOVA allocator still allocates an IOVA range but now adds this range
to the IOVA-only tree as well as to the full IOVA->HVA tree.

In the next patch, the full IOVA->HVA tree will be split into a partial
SVQ IOVA->HVA tree and a GPA->IOVA tree. The motivation behind having an
IOVA-only tree was to have a single tree that would keep track of all
allocated IOVA ranges between the partial SVQ IOVA->HVA and GPA->IOVA
trees.

Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Message-Id: <20250217144936.3589907-2-jonah.palmer@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 231b45246c..5a3a57203d 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -510,14 +510,20 @@ static int vhost_vdpa_cvq_map_buf(struct vhost_vdpa *v, void *buf, size_t size,
                                   bool write)
 {
     DMAMap map = {};
+    hwaddr taddr = (hwaddr)(uintptr_t)buf;
     int r;
 
-    map.translated_addr = (hwaddr)(uintptr_t)buf;
     map.size = size - 1;
     map.perm = write ? IOMMU_RW : IOMMU_RO,
-    r = vhost_iova_tree_map_alloc(v->shared->iova_tree, &map);
+    r = vhost_iova_tree_map_alloc(v->shared->iova_tree, &map, taddr);
     if (unlikely(r != IOVA_OK)) {
         error_report("Cannot map injected element");
+
+        if (map.translated_addr == taddr) {
+            error_report("Insertion to IOVA->HVA tree failed");
+            /* Remove the mapping from the IOVA-only tree */
+            goto dma_map_err;
+        }
         return r;
     }