arch/x86/xen/platform-pci-unplug.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /******************************************************************************
   4  * platform-pci-unplug.c
   5  *
   6  * Xen platform PCI device driver
   7  * Copyright (c) 2010, Citrix
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/io.h>
  12 #include <linux/export.h>
  13
  14 #include <xen/xen.h>
  15 #include <xen/platform_pci.h>
  16 #include "xen-ops.h"
  17
  18 #define XEN_PLATFORM_ERR_MAGIC -1
  19 #define XEN_PLATFORM_ERR_PROTOCOL -2
  20 #define XEN_PLATFORM_ERR_BLACKLIST -3
  21
  22 /* store the value of xen_emul_unplug after the unplug is done */
  23 static int xen_platform_pci_unplug;
  24 static int xen_emul_unplug;
  25
  26 static int check_platform_magic(void)
  27 {
  28         short magic;
  29         char protocol;
  30
  31         magic = inw(XEN_IOPORT_MAGIC);
  32         if (magic != XEN_IOPORT_MAGIC_VAL) {
  33                 printk(KERN_ERR "Xen Platform PCI: unrecognised magic value\n");
  34                 return XEN_PLATFORM_ERR_MAGIC;
  35         }
  36
  37         protocol = inb(XEN_IOPORT_PROTOVER);
  38
  39         printk(KERN_DEBUG "Xen Platform PCI: I/O protocol version %d\n",
  40                         protocol);
  41
  42         switch (protocol) {
  43         case 1:
  44                 outw(XEN_IOPORT_LINUX_PRODNUM, XEN_IOPORT_PRODNUM);
  45                 outl(XEN_IOPORT_LINUX_DRVVER, XEN_IOPORT_DRVVER);
  46                 if (inw(XEN_IOPORT_MAGIC) != XEN_IOPORT_MAGIC_VAL) {
  47                         printk(KERN_ERR "Xen Platform: blacklisted by host\n");
  48                         return XEN_PLATFORM_ERR_BLACKLIST;
  49                 }
  50                 break;
  51         default:
  52                 printk(KERN_WARNING "Xen Platform PCI: unknown I/O protocol version\n");
  53                 return XEN_PLATFORM_ERR_PROTOCOL;
  54         }
  55
  56         return 0;
  57 }
  58
  59 bool xen_has_pv_devices(void)
  60 {
  61         if (!xen_domain())
  62                 return false;
  63
  64         /* PV and PVH domains always have them. */
  65         if (xen_pv_domain() || xen_pvh_domain())
  66                 return true;
  67
  68         /* And user has xen_platform_pci=0 set in guest config as
  69          * driver did not modify the value. */
  70         if (xen_platform_pci_unplug == 0)
  71                 return false;
  72
  73         if (xen_platform_pci_unplug & XEN_UNPLUG_NEVER)
  74                 return false;
  75
  76         if (xen_platform_pci_unplug & XEN_UNPLUG_ALL)
  77                 return true;
  78
  79         /* This is an odd one - we are going to run legacy
  80          * and PV drivers at the same time. */
  81         if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
  82                 return true;
  83
  84         /* And the caller has to follow with xen_pv_{disk,nic}_devices
  85          * to be certain which driver can load. */
  86         return false;
  87 }
  88 EXPORT_SYMBOL_GPL(xen_has_pv_devices);
  89
  90 static bool __xen_has_pv_device(int state)
  91 {
  92         /* HVM domains might or might not */
  93         if (xen_hvm_domain() && (xen_platform_pci_unplug & state))
  94                 return true;
  95
  96         return xen_has_pv_devices();
  97 }
  98
  99 bool xen_has_pv_nic_devices(void)
 100 {
 101         return __xen_has_pv_device(XEN_UNPLUG_ALL_NICS | XEN_UNPLUG_ALL);
 102 }
 103 EXPORT_SYMBOL_GPL(xen_has_pv_nic_devices);
 104
 105 bool xen_has_pv_disk_devices(void)
 106 {
 107         return __xen_has_pv_device(XEN_UNPLUG_ALL_IDE_DISKS |
 108                                    XEN_UNPLUG_AUX_IDE_DISKS | XEN_UNPLUG_ALL);
 109 }
 110 EXPORT_SYMBOL_GPL(xen_has_pv_disk_devices);
 111
 112 /*
 113  * This one is odd - it determines whether you want to run PV _and_
 114  * legacy (IDE) drivers together. This combination is only possible
 115  * under HVM.
 116  */
 117 bool xen_has_pv_and_legacy_disk_devices(void)
 118 {
 119         if (!xen_domain())
 120                 return false;
 121
 122         /* N.B. This is only ever used in HVM mode */
 123         if (xen_pv_domain())
 124                 return false;
 125
 126         if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
 127                 return true;
 128
 129         return false;
 130 }
 131 EXPORT_SYMBOL_GPL(xen_has_pv_and_legacy_disk_devices);
 132
 133 void xen_unplug_emulated_devices(void)
 134 {
 135         int r;
 136
 137         /* PVH guests don't have emulated devices. */
 138         if (xen_pvh_domain())
 139                 return;
 140
 141         /* user explicitly requested no unplug */
 142         if (xen_emul_unplug & XEN_UNPLUG_NEVER)
 143                 return;
 144         /* check the version of the xen platform PCI device */
 145         r = check_platform_magic();
 146         /* If the version matches enable the Xen platform PCI driver.
 147          * Also enable the Xen platform PCI driver if the host does
 148          * not support the unplug protocol (XEN_PLATFORM_ERR_MAGIC)
 149          * but the user told us that unplugging is unnecessary. */
 150         if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
 151                         (xen_emul_unplug & XEN_UNPLUG_UNNECESSARY)))
 152                 return;
 153         /* Set the default value of xen_emul_unplug depending on whether or
 154          * not the Xen PV frontends and the Xen platform PCI driver have
 155          * been compiled for this kernel (modules or built-in are both OK). */
 156         if (!xen_emul_unplug) {
 157                 if (xen_must_unplug_nics()) {
 158                         printk(KERN_INFO "Netfront and the Xen platform PCI driver have "
 159                                         "been compiled for this kernel: unplug emulated NICs.\n");
 160                         xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
 161                 }
 162                 if (xen_must_unplug_disks()) {
 163                         printk(KERN_INFO "Blkfront and the Xen platform PCI driver have "
 164                                         "been compiled for this kernel: unplug emulated disks.\n"
 165                                         "You might have to change the root device\n"
 166                                         "from /dev/hd[a-d] to /dev/xvd[a-d]\n"
 167                                         "in your root= kernel command line option\n");
 168                         xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
 169                 }
 170         }
 171         /* Now unplug the emulated devices */
 172         if (!(xen_emul_unplug & XEN_UNPLUG_UNNECESSARY))
 173                 outw(xen_emul_unplug, XEN_IOPORT_UNPLUG);
 174         xen_platform_pci_unplug = xen_emul_unplug;
 175 }
 176
 177 static int __init parse_xen_emul_unplug(char *arg)
 178 {
 179         char *p, *q;
 180         int l;
 181
 182         for (p = arg; p; p = q) {
 183                 q = strchr(p, ',');
 184                 if (q) {
 185                         l = q - p;
 186                         q++;
 187                 } else {
 188                         l = strlen(p);
 189                 }
 190                 if (!strncmp(p, "all", l))
 191                         xen_emul_unplug |= XEN_UNPLUG_ALL;
 192                 else if (!strncmp(p, "ide-disks", l))
 193                         xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
 194                 else if (!strncmp(p, "aux-ide-disks", l))
 195                         xen_emul_unplug |= XEN_UNPLUG_AUX_IDE_DISKS;
 196                 else if (!strncmp(p, "nics", l))
 197                         xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
 198                 else if (!strncmp(p, "unnecessary", l))
 199                         xen_emul_unplug |= XEN_UNPLUG_UNNECESSARY;
 200                 else if (!strncmp(p, "never", l))
 201                         xen_emul_unplug |= XEN_UNPLUG_NEVER;
 202                 else
 203                         printk(KERN_WARNING "unrecognised option '%s' "
 204                                  "in parameter 'xen_emul_unplug'\n", p);
 205         }
 206         return 0;
 207 }
 208 early_param("xen_emul_unplug", parse_xen_emul_unplug);