4 files changed, 26 insertions, 14 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 2c85c0692b01..f084af0cb8e0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2629,8 +2629,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         aux-ide-disks -- unplug non-primary-master IDE devices
                         nics -- unplug network devices
                         all -- unplug all emulated devices (NICs and IDE disks)
-                        ignore -- continue loading the Xen platform PCI driver even
-                                if the version check failed
+                        unnecessary -- unplugging emulated devices is
+                                unnecessary even if the host did not respond to
+                                the unplug protocol
+                        never -- do not unplug even if version check succeeds
 
         xirc2ps_cs=     [NET,PCMCIA]
                         Format:
diff --git a/arch/x86/xen/platform-pci-unplug.c b/arch/x86/xen/platform-pci-unplug.c
index 554c002a1e1a..0f456386cce5 100644
--- a/arch/x86/xen/platform-pci-unplug.c
+++ b/arch/x86/xen/platform-pci-unplug.c
@@ -72,13 +72,17 @@ void __init xen_unplug_emulated_devices(void)
 {
         int r;
 
+        /* user explicitly requested no unplug */
+        if (xen_emul_unplug & XEN_UNPLUG_NEVER)
+                return;
         /* check the version of the xen platform PCI device */
         r = check_platform_magic();
         /* If the version matches enable the Xen platform PCI driver.
-         * Also enable the Xen platform PCI driver if the version is really old
-         * and the user told us to ignore it. */
+         * Also enable the Xen platform PCI driver if the host does
+         * not support the unplug protocol (XEN_PLATFORM_ERR_MAGIC)
+         * but the user told us that unplugging is unnecessary. */
         if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
-                        (xen_emul_unplug & XEN_UNPLUG_IGNORE)))
+                        (xen_emul_unplug & XEN_UNPLUG_UNNECESSARY)))
                 return;
         /* Set the default value of xen_emul_unplug depending on whether or
          * not the Xen PV frontends and the Xen platform PCI driver have
@@ -99,7 +103,7 @@ void __init xen_unplug_emulated_devices(void)
                 }
         }
         /* Now unplug the emulated devices */
-        if (!(xen_emul_unplug & XEN_UNPLUG_IGNORE))
+        if (!(xen_emul_unplug & XEN_UNPLUG_UNNECESSARY))
                 outw(xen_emul_unplug, XEN_IOPORT_UNPLUG);
         xen_platform_pci_unplug = xen_emul_unplug;
 }
@@ -125,8 +129,10 @@ static int __init parse_xen_emul_unplug(char *arg)
                         xen_emul_unplug |= XEN_UNPLUG_AUX_IDE_DISKS;
                 else if (!strncmp(p, "nics", l))
                         xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
-                else if (!strncmp(p, "ignore", l))
-                        xen_emul_unplug |= XEN_UNPLUG_IGNORE;
+                else if (!strncmp(p, "unnecessary", l))
+                        xen_emul_unplug |= XEN_UNPLUG_UNNECESSARY;
+                else if (!strncmp(p, "never", l))
+                        xen_emul_unplug |= XEN_UNPLUG_NEVER;
                 else
                         printk(KERN_WARNING "unrecognised option '%s' "
                                  "in parameter 'xen_emul_unplug'\n", p);
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index ac1b682edecb..ab735a605cf3 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -834,7 +834,7 @@ static int blkfront_probe(struct xenbus_device *dev,
                 char *type;
                 int len;
                 /* no unplug has been done: do not hook devices != xen vbds */
-                if (xen_platform_pci_unplug & XEN_UNPLUG_IGNORE) {
+                if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
                         int major;
 
                         if (!VDEV_IS_EXTENDED(vdevice))
diff --git a/include/xen/platform_pci.h b/include/xen/platform_pci.h
index ce9d671c636c..a785a3b0c8c7 100644
--- a/include/xen/platform_pci.h
+++ b/include/xen/platform_pci.h
@@ -16,11 +16,15 @@
 #define XEN_IOPORT_PROTOVER     (XEN_IOPORT_BASE + 2) /* 1 byte access (R) */
 #define XEN_IOPORT_PRODNUM      (XEN_IOPORT_BASE + 2) /* 2 byte access (W) */
 
-#define XEN_UNPLUG_ALL_IDE_DISKS 1
-#define XEN_UNPLUG_ALL_NICS 2
-#define XEN_UNPLUG_AUX_IDE_DISKS 4
-#define XEN_UNPLUG_ALL 7
-#define XEN_UNPLUG_IGNORE 8
+#define XEN_UNPLUG_ALL_IDE_DISKS        (1<<0)
+#define XEN_UNPLUG_ALL_NICS             (1<<1)
+#define XEN_UNPLUG_AUX_IDE_DISKS        (1<<2)
+#define XEN_UNPLUG_ALL                  (XEN_UNPLUG_ALL_IDE_DISKS|\
+                                         XEN_UNPLUG_ALL_NICS|\
+                                         XEN_UNPLUG_AUX_IDE_DISKS)
+
+#define XEN_UNPLUG_UNNECESSARY          (1<<16)
+#define XEN_UNPLUG_NEVER                        (1<<17)
 
 static inline int xen_must_unplug_nics(void) {
 #if (defined(CONFIG_XEN_NETDEV_FRONTEND) || \