add pci-bridge-seat

Simplifies multiseat configuration, see
docs/multiseat.txt update for details.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

docs/multiseat.txt

@@ -106,6 +106,25 @@ the devices attached to the seat.
 Background info is here:
   http://www.freedesktop.org/wiki/Software/systemd/multiseat/
 
+
+guest side with pci-bridge-seat
+-------------------------------
+
+Qemu version FIXME and newer has a new pci-bridge-seat device which
+can be used instead of pci-bridge.  Just swap the device name in the
+qemu command line above.  The only difference between the two devices
+is the pci id.  We can match the pci id instead of the device path
+with a nice generic rule now, which simplifies the guest
+configuration:
+
+    [root@fedora ~]# cat /etc/udev/rules.d/70-qemu-pci-bridge-seat.rules
+    SUBSYSTEM=="pci", ATTR{vendor}=="0x1b36", ATTR{device}=="0x000a", \
+            TAG+="seat", ENV{ID_AUTOSEAT}="1"
+
+Patch with this rule will be submitted to upstream udev/systemd, so
+long-term, when systemd with this lands in distros, things will work
+just fine without any manual guest configuration.
+
 Enjoy!
 
 --

docs/specs/pci-ids.txt

@@ -47,6 +47,7 @@ PCI devices (other than virtio):
 1b36:0005  PCI test device (docs/specs/pci-testdev.txt)
 1b36:0006  PCI Rocker Ethernet switch device
 1b36:0007  PCI SD Card Host Controller Interface (SDHCI)
+1b36:000a  PCI-PCI bridge (multiseat)
 
 All these devices are documented in docs/specs.
 

hw/pci-bridge/pci_bridge_dev.c

@@ -28,7 +28,8 @@
 #include "hw/pci/pci_bus.h"
 #include "hw/hotplug.h"
 
-#define TYPE_PCI_BRIDGE_DEV "pci-bridge"
+#define TYPE_PCI_BRIDGE_DEV      "pci-bridge"
+#define TYPE_PCI_BRIDGE_SEAT_DEV "pci-bridge-seat"
 #define PCI_BRIDGE_DEV(obj) \
     OBJECT_CHECK(PCIBridgeDev, (obj), TYPE_PCI_BRIDGE_DEV)
 
@@ -170,9 +171,31 @@ static const TypeInfo pci_bridge_dev_info = {
     }
 };
 
+/*
+ * Multiseat bridge.  Same as the standard pci bridge, only with a
+ * different pci id, so we can match it easily in the guest for
+ * automagic multiseat configuration.  See docs/multiseat.txt for more.
+ */
+static void pci_bridge_dev_seat_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
+
+    k->device_id = PCI_DEVICE_ID_REDHAT_BRIDGE_SEAT;
+    dc->desc = "Standard PCI Bridge (multiseat)";
+}
+
+static const TypeInfo pci_bridge_dev_seat_info = {
+    .name              = TYPE_PCI_BRIDGE_SEAT_DEV,
+    .parent            = TYPE_PCI_BRIDGE_DEV,
+    .instance_size     = sizeof(PCIBridgeDev),
+    .class_init        = pci_bridge_dev_seat_class_init,
+};
+
 static void pci_bridge_dev_register(void)
 {
     type_register_static(&pci_bridge_dev_info);
+    type_register_static(&pci_bridge_dev_seat_info);
 }
 
 type_init(pci_bridge_dev_register);

include/hw/pci/pci.h

@@ -92,6 +92,7 @@
 #define PCI_DEVICE_ID_REDHAT_SDHCI       0x0007
 #define PCI_DEVICE_ID_REDHAT_PCIE_HOST   0x0008
 #define PCI_DEVICE_ID_REDHAT_PXB         0x0009
+#define PCI_DEVICE_ID_REDHAT_BRIDGE_SEAT 0x000a
 #define PCI_DEVICE_ID_REDHAT_QXL         0x0100
 
 #define FMT_PCIBUS                      PRIx64