block/nvme: Have nvme_create_queue_pair() report errors consistently

nvme_create_queue_pair() does not return a boolean value (indicating
eventual error) but a pointer, and is inconsistent in how it fills the
error handler. To fulfill callers expectations, always set an error
message on failure.

Reported-by: Auger Eric <[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

@@ -220,6 +220,7 @@ static NVMeQueuePair *nvme_create_queue_pair(BDRVNVMeState *s,
 
     q = g_try_new0(NVMeQueuePair, 1);
     if (!q) {
+        error_setg(errp, "Cannot allocate queue pair");
         return NULL;
     }
     trace_nvme_create_queue_pair(idx, q, size, aio_context,
@@ -228,6 +229,7 @@ static NVMeQueuePair *nvme_create_queue_pair(BDRVNVMeState *s,
                           qemu_real_host_page_size);
     q->prp_list_pages = qemu_try_memalign(qemu_real_host_page_size, bytes);
     if (!q->prp_list_pages) {
+        error_setg(errp, "Cannot allocate PRP page list");
         goto fail;
     }
     memset(q->prp_list_pages, 0, bytes);
@@ -239,6 +241,7 @@ static NVMeQueuePair *nvme_create_queue_pair(BDRVNVMeState *s,
     r = qemu_vfio_dma_map(s->vfio, q->prp_list_pages, bytes,
                           false, &prp_list_iova);
     if (r) {
+        error_setg_errno(errp, -r, "Cannot map buffer for DMA");
         goto fail;
     }
     q->free_req_head = -1;