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>

9 files changed, 225 insertions, 1 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82d6aeb5228f..eefcd805102e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -115,6 +115,7 @@ parameter is applicable:
                         More X86-64 boot options can be found in
                         Documentation/x86/x86_64/boot-options.txt .
         X86     Either 32bit or 64bit x86 (same as X86-32+X86-64)
+        XEN     Xen support is enabled
 
 In addition, the following text indicates that the option:
 
@@ -2879,6 +2880,16 @@ and is between 256 and 4096 characters. It is defined in the file
         xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
         xd_geo=         See header of drivers/block/xd.c.
 
+        xen_emul_unplug=                [HW,X86,XEN]
+                        Unplug Xen emulated devices
+                        Format: [unplug0,][unplug1]
+                        ide-disks -- unplug primary master IDE devices
+                        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
+
         xirc2ps_cs=     [NET,PCMCIA]
                         Format:
                         <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 3bb4fc21f4f2..930954685980 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -12,7 +12,7 @@ CFLAGS_mmu.o			:= $(nostackp)
 
 obj-y           := enlighten.o setup.o multicalls.o mmu.o irq.o \
                         time.o xen-asm.o xen-asm_$(BITS).o \
-                        grant-table.o suspend.o
+                        grant-table.o suspend.o platform-pci-unplug.o
 
 obj-$(CONFIG_SMP)               += smp.o
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index a90172963884..157c93b62dd4 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1314,6 +1314,7 @@ static void __init xen_hvm_guest_init(void)
         if (xen_feature(XENFEAT_hvm_callback_vector))
                 xen_have_vector_callback = 1;
         register_cpu_notifier(&xen_hvm_cpu_notifier);
+        xen_unplug_emulated_devices();
         have_vcpu_info_placement = 0;
         x86_init.irqs.intr_init = xen_init_IRQ;
         xen_hvm_init_time_ops();
diff --git a/arch/x86/xen/platform-pci-unplug.c b/arch/x86/xen/platform-pci-unplug.c
new file mode 100644
index 000000000000..2f7f3fb34777
--- /dev/null
+++ b/arch/x86/xen/platform-pci-unplug.c
@@ -0,0 +1,135 @@
+/******************************************************************************
+ * platform-pci-unplug.c
+ *
+ * Xen platform PCI device driver
+ * Copyright (c) 2010, Citrix
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+
+#include <xen/platform_pci.h>
+
+#define XEN_PLATFORM_ERR_MAGIC -1
+#define XEN_PLATFORM_ERR_PROTOCOL -2
+#define XEN_PLATFORM_ERR_BLACKLIST -3
+
+/* store the value of xen_emul_unplug after the unplug is done */
+int xen_platform_pci_unplug;
+EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
+static int xen_emul_unplug;
+
+static int __init check_platform_magic(void)
+{
+        short magic;
+        char protocol;
+
+        magic = inw(XEN_IOPORT_MAGIC);
+        if (magic != XEN_IOPORT_MAGIC_VAL) {
+                printk(KERN_ERR "Xen Platform PCI: unrecognised magic value\n");
+                return XEN_PLATFORM_ERR_MAGIC;
+        }
+
+        protocol = inb(XEN_IOPORT_PROTOVER);
+
+        printk(KERN_DEBUG "Xen Platform PCI: I/O protocol version %d\n",
+                        protocol);
+
+        switch (protocol) {
+        case 1:
+                outw(XEN_IOPORT_LINUX_PRODNUM, XEN_IOPORT_PRODNUM);
+                outl(XEN_IOPORT_LINUX_DRVVER, XEN_IOPORT_DRVVER);
+                if (inw(XEN_IOPORT_MAGIC) != XEN_IOPORT_MAGIC_VAL) {
+                        printk(KERN_ERR "Xen Platform: blacklisted by host\n");
+                        return XEN_PLATFORM_ERR_BLACKLIST;
+                }
+                break;
+        default:
+                printk(KERN_WARNING "Xen Platform PCI: unknown I/O protocol version");
+                return XEN_PLATFORM_ERR_PROTOCOL;
+        }
+
+        return 0;
+}
+
+void __init xen_unplug_emulated_devices(void)
+{
+        int r;
+
+        /* 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. */
+        if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
+                        (xen_emul_unplug & XEN_UNPLUG_IGNORE)))
+                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
+         * been compiled for this kernel (modules or built-in are both OK). */
+        if (!xen_emul_unplug) {
+                if (xen_must_unplug_nics()) {
+                        printk(KERN_INFO "Netfront and the Xen platform PCI driver have "
+                                        "been compiled for this kernel: unplug emulated NICs.\n");
+                        xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
+                }
+                if (xen_must_unplug_disks()) {
+                        printk(KERN_INFO "Blkfront and the Xen platform PCI driver have "
+                                        "been compiled for this kernel: unplug emulated disks.\n"
+                                        "You might have to change the root device\n"
+                                        "from /dev/hd[a-d] to /dev/xvd[a-d]\n"
+                                        "in your root= kernel command line option\n");
+                        xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
+                }
+        }
+        /* Now unplug the emulated devices */
+        if (!(xen_emul_unplug & XEN_UNPLUG_IGNORE))
+                outw(xen_emul_unplug, XEN_IOPORT_UNPLUG);
+        xen_platform_pci_unplug = xen_emul_unplug;
+}
+
+static int __init parse_xen_emul_unplug(char *arg)
+{
+        char *p, *q;
+        int l;
+
+        for (p = arg; p; p = q) {
+                q = strchr(p, ',');
+                if (q) {
+                        l = q - p;
+                        q++;
+                } else {
+                        l = strlen(p);
+                }
+                if (!strncmp(p, "all", l))
+                        xen_emul_unplug |= XEN_UNPLUG_ALL;
+                else if (!strncmp(p, "ide-disks", l))
+                        xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
+                else if (!strncmp(p, "aux-ide-disks", l))
+                        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
+                        printk(KERN_WARNING "unrecognised option '%s' "
+                                 "in parameter 'xen_emul_unplug'\n", p);
+        }
+        return 0;
+}
+early_param("xen_emul_unplug", parse_xen_emul_unplug);
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 089d18923d2b..ed776949024c 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -40,6 +40,7 @@ void xen_vcpu_restore(void);
 
 void xen_callback_vector(void);
 void xen_hvm_init_shared_info(void);
+void __init xen_unplug_emulated_devices(void);
 
 void __init xen_build_dynamic_phys_to_machine(void);
 
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");
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;
diff --git a/include/xen/platform_pci.h b/include/xen/platform_pci.h
new file mode 100644
index 000000000000..ce9d671c636c
--- /dev/null
+++ b/include/xen/platform_pci.h
@@ -0,0 +1,49 @@
+#ifndef _XEN_PLATFORM_PCI_H
+#define _XEN_PLATFORM_PCI_H
+
+#define XEN_IOPORT_MAGIC_VAL 0x49d2
+#define XEN_IOPORT_LINUX_PRODNUM 0x0003
+#define XEN_IOPORT_LINUX_DRVVER  0x0001
+
+#define XEN_IOPORT_BASE 0x10
+
+#define XEN_IOPORT_PLATFLAGS    (XEN_IOPORT_BASE + 0) /* 1 byte access (R/W) */
+#define XEN_IOPORT_MAGIC        (XEN_IOPORT_BASE + 0) /* 2 byte access (R) */
+#define XEN_IOPORT_UNPLUG       (XEN_IOPORT_BASE + 0) /* 2 byte access (W) */
+#define XEN_IOPORT_DRVVER       (XEN_IOPORT_BASE + 0) /* 4 byte access (W) */
+
+#define XEN_IOPORT_SYSLOG       (XEN_IOPORT_BASE + 2) /* 1 byte access (W) */
+#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
+
+static inline int xen_must_unplug_nics(void) {
+#if (defined(CONFIG_XEN_NETDEV_FRONTEND) || \
+                defined(CONFIG_XEN_NETDEV_FRONTEND_MODULE)) && \
+                (defined(CONFIG_XEN_PLATFORM_PCI) || \
+                 defined(CONFIG_XEN_PLATFORM_PCI_MODULE))
+        return 1;
+#else
+        return 0;
+#endif
+}
+
+static inline int xen_must_unplug_disks(void) {
+#if (defined(CONFIG_XEN_BLKDEV_FRONTEND) || \
+                defined(CONFIG_XEN_BLKDEV_FRONTEND_MODULE)) && \
+                (defined(CONFIG_XEN_PLATFORM_PCI) || \
+                 defined(CONFIG_XEN_PLATFORM_PCI_MODULE))
+        return 1;
+#else
+        return 0;
+#endif
+}
+
+extern int xen_platform_pci_unplug;
+
+#endif /* _XEN_PLATFORM_PCI_H */