handle_dma_map_or_unmap(): correct fd handling (#118)

We shouldn't consume fd's for regions lacking VFIO_USER_F_DMA_REGION_MAPPABLE.
In addition, we'll ignore such a region (this is a temporary hack).

Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>
Signed-off-by: John Levon <john.levon@nutanix.com>

1 files changed, 24 insertions, 14 deletions

diff --git a/lib/muser_ctx.c b/lib/muser_ctx.c
index 6f01d41..e1b18b1 100644
--- a/lib/muser_ctx.c
+++ b/lib/muser_ctx.c
@@ -504,8 +504,9 @@ handle_dma_map_or_unmap(lm_ctx_t *lm_ctx, uint32_t size, bool map,
                         int *fds, int nr_fds,
                         struct vfio_user_dma_region *dma_regions)
 {
-    int ret, i;
     int nr_dma_regions;
+    int fdi = 0;
+    int ret, i;
 
     assert(lm_ctx != NULL);
 
@@ -519,40 +520,49 @@ handle_dma_map_or_unmap(lm_ctx_t *lm_ctx, uint32_t size, bool map,
     }
 
     nr_dma_regions = (int)(size / sizeof(struct vfio_user_dma_region));
-    if (map && nr_dma_regions != nr_fds) {
-        lm_log(lm_ctx, LM_ERR, "expected %d fds but got %d instead",
-               nr_dma_regions, nr_fds);
-        return -EINVAL;
-    }
 
     for (i = 0; i < nr_dma_regions; i++) {
         if (map) {
+            int fd;
+
+            /*
+             * FIXME: need a dma controller that allows non-fd region.
+             */
             if (dma_regions[i].flags != VFIO_USER_F_DMA_REGION_MAPPABLE) {
-                /*
-                 * FIXME implement non-mappable DMA regions. This requires changing
-                 * dma.c to not take a file descriptor.
-                 */
-                assert(false);
+                lm_log(lm_ctx, LM_INF,
+                       "FIXME: ignored non-mappable DMA region "
+                       "%#lx-%#lx offset=%#lx",
+                       dma_regions[i].addr,
+                       dma_regions[i].addr + dma_regions[i].size - 1,
+                       dma_regions[i].offset);
+                continue;
             }
 
+            if (fdi >= nr_fds) {
+                lm_log(lm_ctx, LM_ERR, "missing fd for mappable region %d", i);
+                return -EINVAL;
+            }
+
+            fd = fds[fdi++];
+
             ret = dma_controller_add_region(lm_ctx->dma,
                                             dma_regions[i].addr,
                                             dma_regions[i].size,
-                                            fds[i],
+                                            fd,
                                             dma_regions[i].offset);
             if (ret < 0) {
                 lm_log(lm_ctx, LM_INF,
                        "failed to add DMA region %#lx-%#lx offset=%#lx fd=%d: %s",
                        dma_regions[i].addr,
                        dma_regions[i].addr + dma_regions[i].size - 1,
-                       dma_regions[i].offset, fds[i],
+                       dma_regions[i].offset, fd,
                        strerror(-ret));
             } else {
                 lm_log(lm_ctx, LM_DBG,
                        "added DMA region %#lx-%#lx offset=%#lx fd=%d",
                        dma_regions[i].addr,
                        dma_regions[i].addr + dma_regions[i].size - 1,
-                       dma_regions[i].offset, fds[i]);
+                       dma_regions[i].offset, fd);
             }
         } else {
             ret = dma_controller_remove_region(lm_ctx->dma,