block/nvme: Only report VFIO error on failed retry

We expect the first qemu_vfio_dma_map() to fail (indicating
DMA mappings exhaustion, see commit 15a730e). Do not
report the first failure as error, since we are going to
flush the mappings and retry.

This removes spurious error message displayed on the monitor:

  (qemu) c
  (qemu) qemu-kvm: VFIO_MAP_DMA failed: No space left on device
  (qemu) info status
  VM status: running

Reported-by: Tingting Mao <[email protected]>
Reviewed-by: Klaus Jensen <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: [email protected]
Signed-off-by: Stefan Hajnoczi <[email protected]>

Author: philmd

block/nvme.c

@@ -1019,6 +1019,7 @@ static coroutine_fn int nvme_cmd_map_qiov(BlockDriverState *bs, NvmeCmd *cmd,
     uint64_t *pagelist = req->prp_list_page;
     int i, j, r;
     int entries = 0;
+    Error *local_err = NULL, **errp = NULL;
 
     assert(qiov->size);
     assert(QEMU_IS_ALIGNED(qiov->size, s->page_size));
@@ -1031,7 +1032,7 @@ static coroutine_fn int nvme_cmd_map_qiov(BlockDriverState *bs, NvmeCmd *cmd,
 try_map:
         r = qemu_vfio_dma_map(s->vfio,
                               qiov->iov[i].iov_base,
-                              len, true, &iova, NULL);
+                              len, true, &iova, errp);
         if (r == -ENOSPC) {
             /*
              * In addition to the -ENOMEM error, the VFIO_IOMMU_MAP_DMA
@@ -1066,6 +1067,8 @@ static coroutine_fn int nvme_cmd_map_qiov(BlockDriverState *bs, NvmeCmd *cmd,
                     goto fail;
                 }
             }
+            errp = &local_err;
+
             goto try_map;
         }
         if (r) {
@@ -1109,6 +1112,9 @@ static coroutine_fn int nvme_cmd_map_qiov(BlockDriverState *bs, NvmeCmd *cmd,
      * because they are already mapped before calling this function; for
      * temporary mappings, a later nvme_cmd_(un)map_qiov will reclaim by
      * calling qemu_vfio_dma_reset_temporary when necessary. */
+    if (local_err) {
+        error_reportf_err(local_err, "Cannot map buffer for DMA: ");
+    }
     return r;
 }