vfio/pci: add support for VF token

VF token was introduced [1] to kernel vfio-pci along with SR-IOV
support [2].  This patch adds support VF token among PF and VF(s). To
passthu PCIe VF to a VM, kernel >= v5.7 needs this.

It can be configured with UUID like:

  -device vfio-pci,host=DDDD:BB:DD:F,vf-token=<uuid>,...

[1] https://lore.kernel.org/linux-pci/158396393244.5601.10297430724964025753.stgit@gimli.home/
[2] https://lore.kernel.org/linux-pci/158396044753.5601.14804870681174789709.stgit@gimli.home/

Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Minwoo Im <minwoo.im@samsung.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Link: https://lore.kernel.org/r/20230320073522epcms2p48f682ecdb73e0ae1a4850ad0712fd780@epcms2p4
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/vfio/pci.c

@@ -2856,6 +2856,8 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     int groupid;
     int i, ret;
     bool is_mdev;
+    char uuid[UUID_FMT_LEN];
+    char *name;
 
     if (!vbasedev->sysfsdev) {
         if (!(~vdev->host.domain || ~vdev->host.bus ||
@@ -2936,7 +2938,15 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         goto error;
     }
 
-    ret = vfio_get_device(group, vbasedev->name, vbasedev, errp);
+    if (!qemu_uuid_is_null(&vdev->vf_token)) {
+        qemu_uuid_unparse(&vdev->vf_token, uuid);
+        name = g_strdup_printf("%s vf_token=%s", vbasedev->name, uuid);
+    } else {
+        name = vbasedev->name;
+    }
+
+    ret = vfio_get_device(group, name, vbasedev, errp);
+    g_free(name);
     if (ret) {
         vfio_put_group(group);
         goto error;
@@ -3268,6 +3278,7 @@ static void vfio_instance_init(Object *obj)
 
 static Property vfio_pci_dev_properties[] = {
     DEFINE_PROP_PCI_HOST_DEVADDR("host", VFIOPCIDevice, host),
+    DEFINE_PROP_UUID_NODEFAULT("vf-token", VFIOPCIDevice, vf_token),
     DEFINE_PROP_STRING("sysfsdev", VFIOPCIDevice, vbasedev.sysfsdev),
     DEFINE_PROP_ON_OFF_AUTO("x-pre-copy-dirty-page-tracking", VFIOPCIDevice,
                             vbasedev.pre_copy_dirty_page_tracking,

hw/vfio/pci.h

@@ -137,6 +137,7 @@ struct VFIOPCIDevice {
     VFIOVGA *vga; /* 0xa0000, 0x3b0, 0x3c0 */
     void *igd_opregion;
     PCIHostDeviceAddress host;
+    QemuUUID vf_token;
     EventNotifier err_notifier;
     EventNotifier req_notifier;
     int (*resetfn)(struct VFIOPCIDevice *);