x86: Unplug emulated disks and nics.

Add a xen_emul_unplug command line option to the kernel to unplug
xen emulated disks and nics.

Set the default value of xen_emul_unplug depending on whether or
not the Xen PV frontends and the Xen platform PCI driver have
been compiled for this kernel (modules or built-in are both OK).

The user can specify xen_emul_unplug=ignore to enable PV drivers on HVM
even if the host platform doesn't support unplug.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

2 files changed, 10 insertions, 0 deletions

diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
index bdb44f2473e8..c01b5ddce529 100644
--- a/drivers/xen/platform-pci.c
+++ b/drivers/xen/platform-pci.c
@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 
+#include <xen/platform_pci.h>
 #include <xen/grant_table.h>
 #include <xen/xenbus.h>
 #include <xen/events.h>
@@ -195,6 +196,11 @@ static struct pci_driver platform_driver = {
 
 static int __init platform_pci_module_init(void)
 {
+        /* no unplug has been done, IGNORE hasn't been specified: just
+         * return now */
+        if (!xen_platform_pci_unplug)
+                return -ENODEV;
+
         return pci_register_driver(&platform_driver);
 }
 
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index a9e83c438cbb..37e8894b50d6 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -56,6 +56,7 @@
 #include <xen/events.h>
 #include <xen/page.h>
 
+#include <xen/platform_pci.h>
 #include <xen/hvm.h>
 
 #include "xenbus_comms.h"
@@ -977,6 +978,9 @@ static void wait_for_devices(struct xenbus_driver *xendrv)
 #ifndef MODULE
 static int __init boot_wait_for_devices(void)
 {
+        if (xen_hvm_domain() && !xen_platform_pci_unplug)
+                return -ENODEV;
+
         ready_to_wait_for_devices = 1;
         wait_for_devices(NULL);
         return 0;