vfio/pci: Handle host oversight

In case the end-user calls qemu with -vfio-pci option without passing
either sysfsdev or host property value, the device is interpreted as
0000:00:00.0. Let's create a specific error message to guide the end-user.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 6d013249fcc115e1e11fa5fc13be504b358e8e9f..fef436a1de6fcae327d7d41b124d3e6330e5bfc3 100644 (file)
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2520,6 +2520,13 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     int i, ret;
 
     if (!vdev->vbasedev.sysfsdev) {
+        if (!(~vdev->host.domain || ~vdev->host.bus ||
+              ~vdev->host.slot || ~vdev->host.function)) {
+            error_setg(errp, "No provided host device");
+            error_append_hint(errp, "Use -vfio-pci,host=DDDD:BB:DD.F "
+                              "or -vfio-pci,sysfsdev=PATH_TO_DEVICE\n");
+            return;
+        }
         vdev->vbasedev.sysfsdev =
             g_strdup_printf("/sys/bus/pci/devices/%04x:%02x:%02x.%01x",
                             vdev->host.domain, vdev->host.bus,
@@ -2828,6 +2835,10 @@ static void vfio_instance_init(Object *obj)
     device_add_bootindex_property(obj, &vdev->bootindex,
                                   "bootindex", NULL,
                                   &pci_dev->qdev, NULL);
+    vdev->host.domain = ~0U;
+    vdev->host.bus = ~0U;
+    vdev->host.slot = ~0U;
+    vdev->host.function = ~0U;
 }
 
 static Property vfio_pci_dev_properties[] = {