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>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 82ed403147c0..6eb2989a9d0a 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -48,6 +48,7 @@
 #include <xen/grant_table.h>
 #include <xen/events.h>
 #include <xen/page.h>
+#include <xen/platform_pci.h>
 
 #include <xen/interface/grant_table.h>
 #include <xen/interface/io/blkif.h>
@@ -737,6 +738,22 @@ static int blkfront_probe(struct xenbus_device *dev,
                 }
         }
 
+        /* no unplug has been done: do not hook devices != xen vbds */
+        if (xen_hvm_domain() && (xen_platform_pci_unplug & XEN_UNPLUG_IGNORE)) {
+                int major;
+
+                if (!VDEV_IS_EXTENDED(vdevice))
+                        major = BLKIF_MAJOR(vdevice);
+                else
+                        major = XENVBD_MAJOR;
+
+                if (major != XENVBD_MAJOR) {
+                        printk(KERN_INFO
+                                        "%s: HVM does not support vbd %d as xen block device\n",
+                                        __FUNCTION__, vdevice);
+                        return -ENODEV;
+                }
+        }
         info = kzalloc(sizeof(*info), GFP_KERNEL);
         if (!info) {
                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");