diff --git a/src/virglrenderer.c b/src/virglrenderer.c
index 739efa7..c20633e 100644
--- a/src/virglrenderer.c
+++ b/src/virglrenderer.c
@@ -72,11 +72,11 @@ void virgl_renderer_context_destroy(uint32_t handle)
    vrend_renderer_context_destroy(handle);
 }
 
-void virgl_renderer_submit_cmd(void *buffer,
-                               int ctx_id,
-                               int ndw)
+int virgl_renderer_submit_cmd(void *buffer,
+			      int ctx_id,
+			      int ndw)
 {
-   vrend_decode_block(ctx_id, buffer, ndw);
+  return vrend_decode_block(ctx_id, buffer, ndw);
 }
 
 int virgl_renderer_transfer_write_iov(uint32_t handle,
diff --git a/src/virglrenderer.h b/src/virglrenderer.h
index bc67163..ceca2ac 100644
--- a/src/virglrenderer.h
+++ b/src/virglrenderer.h
@@ -92,9 +92,9 @@ VIRGL_EXPORT void virgl_renderer_resource_unref(uint32_t res_handle);
 VIRGL_EXPORT int virgl_renderer_context_create(uint32_t handle, uint32_t nlen, const char *name);
 VIRGL_EXPORT void virgl_renderer_context_destroy(uint32_t handle);
 
-VIRGL_EXPORT void virgl_renderer_submit_cmd(void *buffer,
-                                            int ctx_id,
-                                            int ndw);
+VIRGL_EXPORT int virgl_renderer_submit_cmd(void *buffer,
+					   int ctx_id,
+					   int ndw);
 
 VIRGL_EXPORT int virgl_renderer_transfer_read_iov(uint32_t handle, uint32_t ctx_id,
                                                    uint32_t level, uint32_t stride,
diff --git a/src/vrend_decode.c b/src/vrend_decode.c
index 2fc821b..6bd6101 100644
--- a/src/vrend_decode.c
+++ b/src/vrend_decode.c
@@ -1033,22 +1033,22 @@ struct vrend_context *vrend_lookup_renderer_ctx(uint32_t ctx_id)
    return dec_ctx[ctx_id]->grctx;
 }
 
-void vrend_decode_block(uint32_t ctx_id, uint32_t *block, int ndw)
+int vrend_decode_block(uint32_t ctx_id, uint32_t *block, int ndw)
 {
    struct vrend_decode_ctx *gdctx;
    boolean bret;
    int ret;
    if (ctx_id > VREND_MAX_CTX)
-      return;
+      return EINVAL;
 
    if (dec_ctx[ctx_id] == NULL)
-      return;
+      return EINVAL;
 
    gdctx = dec_ctx[ctx_id];
 
    bret = vrend_hw_switch_context(gdctx->grctx, TRUE);
    if (bret == FALSE)
-      return;
+      return EINVAL;
 
    gdctx->ds->buf = block;
    gdctx->ds->buf_total = ndw;
@@ -1161,13 +1161,15 @@ void vrend_decode_block(uint32_t ctx_id, uint32_t *block, int ndw)
 
       if (ret == EINVAL) {
          vrend_report_buffer_error(gdctx->grctx, header);
-         break;
+         goto out;
       }
       if (ret == ENOMEM)
-         break;
+	goto out;
       gdctx->ds->buf_offset += (len) + 1;
    }
-
+   return 0;
+out:
+   return ret;
 }
 
 void vrend_decode_reset(bool ctx_0_only)
diff --git a/src/vrend_renderer.c b/src/vrend_renderer.c
index c905eec..604e51a 100644
--- a/src/vrend_renderer.c
+++ b/src/vrend_renderer.c
@@ -393,7 +393,7 @@ static inline const char *pipe_shader_to_prefix(int shader_type)
    return NULL;
 }
 
-static const char *vrend_ctx_error_strings[] = { "None", "Unknown", "Illegal shader", "Illegal handle", "Illegal resource", "Illegal surface", "Illegal vertex format" };
+static const char *vrend_ctx_error_strings[] = { "None", "Unknown", "Illegal shader", "Illegal handle", "Illegal resource", "Illegal surface", "Illegal vertex format", "Illegal command buffer" };
 
 static void __report_context_error(const char *fname, struct vrend_context *ctx, enum virgl_ctx_errors error, uint32_t value)
 {
diff --git a/src/vrend_renderer.h b/src/vrend_renderer.h
index 1700ded..57566ee 100644
--- a/src/vrend_renderer.h
+++ b/src/vrend_renderer.h
@@ -281,7 +281,7 @@ void vrend_transfer_write_tex_return(struct pipe_resource *res,
 
 void vrend_renderer_fini(void);
 
-void vrend_decode_block(uint32_t ctx_id, uint32_t *block, int ndw);
+int vrend_decode_block(uint32_t ctx_id, uint32_t *block, int ndw);
 struct vrend_context *vrend_lookup_renderer_ctx(uint32_t ctx_id);
 
 int vrend_renderer_create_fence(int client_fence_id, uint32_t ctx_id);