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>

4 files changed, 138 insertions, 1 deletions

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);