xen/pciback: Have 'passthrough' option instead of XEN_PCIDEV_BACKEND_PASS and XEN_PCIDEV_BACKEND_VPCI

.. compile options. This way the user can decide during runtime whether they
want the default 'vpci' (virtual pci passthrough) or where the PCI devices
are passed in without any BDF renumbering. The option 'passthrough' allows
the user to toggle the it from 0 (vpci) to 1 (passthrough).

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/Kconfig

@@ -109,34 +109,22 @@ config XEN_PCIDEV_BACKEND
 	tristate "Xen PCI-device backend driver"
 	depends on PCI && X86 && XEN
 	depends on XEN_BACKEND
+	default m
 	help
 	  The PCI device backend driver allows the kernel to export arbitrary
 	  PCI devices to other guests. If you select this to be a module, you
 	  will need to make sure no other driver has bound to the device(s)
 	  you want to make visible to other guests.
 
-choice
-	prompt "PCI Backend Mode"
-	depends on XEN_PCIDEV_BACKEND
+	  The parameter "passthrough" allows you specify how you want the PCI
+	  devices to appear in the guest. You can choose the default (0) where
+	  PCI topology starts at 00.00.0, or (1) for passthrough if you want
+	  the PCI devices topology appear the same as in the host.
 
-config XEN_PCIDEV_BACKEND_VPCI
-	bool "Virtual PCI"
-	help
-	  This PCI Backend hides the true PCI topology and makes the frontend
-	  think there is a single PCI bus with only the exported devices on it.
-	  For example, a device at 03:05.0 will be re-assigned to 00:00.0. A
-	  second device at 02:1a.1 will be re-assigned to 00:01.1.
-
-config XEN_PCIDEV_BACKEND_PASS
-	bool "Passthrough"
-	help
-	  This PCI Backend provides a real view of the PCI topology to the
-	  frontend (for example, a device at 06:01.b will still appear at
-	  06:01.b to the frontend). This is similar to how Xen 2.0.x exposed
-	  PCI devices to its driver domains. This may be required for drivers
-	  which depend on finding their hardward in certain bus/slot
-	  locations.
-
-endchoice
+	  The "hide" parameter (only applicable if backend driver is compiled
+	  into the kernel) allows you to bind the PCI devices to this module
+	  from the default device drivers. The argument is the list of PCI BDFs:
+	  xen-pciback.hide=(03:00.0)(04:00.0)
 
+	  If in doubt, say m.
 endmenu