libxl: start pvqemu when 9pfs is requested

PV 9pfs requires the PV backend in QEMU. Make sure that libxl knows it.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

tools/libxl/libxl_dm.c

@@ -2598,7 +2598,7 @@ int libxl__need_xenpv_qemu(libxl__gc *gc, libxl_domain_config *d_config)
         goto out;
     }
 
-    if (d_config->num_vfbs > 0) {
+    if (d_config->num_vfbs > 0 || d_config->num_p9s > 0) {
         ret = 1;
         goto out;
     }