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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/init.h>
  13 #include <linux/io.h>
  14 #include <linux/export.h>
  15
  16 #include <xen/xen.h>
  17 #include <xen/platform_pci.h>
  18 #include "xen-ops.h"
  19
  20 #define XEN_PLATFORM_ERR_MAGIC -1
  21 #define XEN_PLATFORM_ERR_PROTOCOL -2
  22 #define XEN_PLATFORM_ERR_BLACKLIST -3
  23
  24 /* store the value of xen_emul_unplug after the unplug is done */
  25 static int xen_platform_pci_unplug;
  26 static int xen_emul_unplug;
  27
  28 static int check_platform_magic(void)
  29 {
  30         short magic;
  31         char protocol;
  32
  33         magic = inw(XEN_IOPORT_MAGIC);
  34         if (magic != XEN_IOPORT_MAGIC_VAL) {
  35                 pr_err("Xen Platform PCI: unrecognised magic value\n");
  36                 return XEN_PLATFORM_ERR_MAGIC;
  37         }
  38
  39         protocol = inb(XEN_IOPORT_PROTOVER);
  40
  41         pr_debug("Xen Platform PCI: I/O protocol version %d\n",
  42                         protocol);
  43
  44         switch (protocol) {
  45         case 1:
  46                 outw(XEN_IOPORT_LINUX_PRODNUM, XEN_IOPORT_PRODNUM);
  47                 outl(XEN_IOPORT_LINUX_DRVVER, XEN_IOPORT_DRVVER);
  48                 if (inw(XEN_IOPORT_MAGIC) != XEN_IOPORT_MAGIC_VAL) {
  49                         pr_err("Xen Platform: blacklisted by host\n");
  50                         return XEN_PLATFORM_ERR_BLACKLIST;
  51                 }
  52                 break;
  53         default:
  54                 pr_warn("Xen Platform PCI: unknown I/O protocol version\n");
  55                 return XEN_PLATFORM_ERR_PROTOCOL;
  56         }
  57
  58         return 0;
  59 }
  60
  61 bool xen_has_pv_devices(void)
  62 {
  63         if (!xen_domain())
  64                 return false;
  65
  66         /* PV and PVH domains always have them. */
  67         if (xen_pv_domain() || xen_pvh_domain())
  68                 return true;
  69
  70         /* And user has xen_platform_pci=0 set in guest config as
  71          * driver did not modify the value. */
  72         if (xen_platform_pci_unplug == 0)
  73                 return false;
  74
  75         if (xen_platform_pci_unplug & XEN_UNPLUG_NEVER)
  76                 return false;
  77
  78         if (xen_platform_pci_unplug & XEN_UNPLUG_ALL)
  79                 return true;
  80
  81         /* This is an odd one - we are going to run legacy
  82          * and PV drivers at the same time. */
  83         if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
  84                 return true;
  85
  86         /* And the caller has to follow with xen_pv_{disk,nic}_devices
  87          * to be certain which driver can load. */
  88         return false;
  89 }
  90 EXPORT_SYMBOL_GPL(xen_has_pv_devices);
  91
  92 static bool __xen_has_pv_device(int state)
  93 {
  94         /* HVM domains might or might not */
  95         if (xen_hvm_domain() && (xen_platform_pci_unplug & state))
  96                 return true;
  97
  98         return xen_has_pv_devices();
  99 }
 100
 101 bool xen_has_pv_nic_devices(void)
 102 {
 103         return __xen_has_pv_device(XEN_UNPLUG_ALL_NICS | XEN_UNPLUG_ALL);
 104 }
 105 EXPORT_SYMBOL_GPL(xen_has_pv_nic_devices);
 106
 107 bool xen_has_pv_disk_devices(void)
 108 {
 109         return __xen_has_pv_device(XEN_UNPLUG_ALL_IDE_DISKS |
 110                                    XEN_UNPLUG_AUX_IDE_DISKS | XEN_UNPLUG_ALL);
 111 }
 112 EXPORT_SYMBOL_GPL(xen_has_pv_disk_devices);
 113
 114 /*
 115  * This one is odd - it determines whether you want to run PV _and_
 116  * legacy (IDE) drivers together. This combination is only possible
 117  * under HVM.
 118  */
 119 bool xen_has_pv_and_legacy_disk_devices(void)
 120 {
 121         if (!xen_domain())
 122                 return false;
 123
 124         /* N.B. This is only ever used in HVM mode */
 125         if (xen_pv_domain())
 126                 return false;
 127
 128         if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
 129                 return true;
 130
 131         return false;
 132 }
 133 EXPORT_SYMBOL_GPL(xen_has_pv_and_legacy_disk_devices);
 134
 135 void xen_unplug_emulated_devices(void)
 136 {
 137         int r;
 138
 139         /* PVH guests don't have emulated devices. */
 140         if (xen_pvh_domain())
 141                 return;
 142
 143         /* user explicitly requested no unplug */
 144         if (xen_emul_unplug & XEN_UNPLUG_NEVER)
 145                 return;
 146         /* check the version of the xen platform PCI device */
 147         r = check_platform_magic();
 148         /* If the version matches enable the Xen platform PCI driver.
 149          * Also enable the Xen platform PCI driver if the host does
 150          * not support the unplug protocol (XEN_PLATFORM_ERR_MAGIC)
 151          * but the user told us that unplugging is unnecessary. */
 152         if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
 153                         (xen_emul_unplug & XEN_UNPLUG_UNNECESSARY)))
 154                 return;
 155         /* Set the default value of xen_emul_unplug depending on whether or
 156          * not the Xen PV frontends and the Xen platform PCI driver have
 157          * been compiled for this kernel (modules or built-in are both OK). */
 158         if (!xen_emul_unplug) {
 159                 if (xen_must_unplug_nics()) {
 160                         pr_info("Netfront and the Xen platform PCI driver have "
 161                                         "been compiled for this kernel: unplug emulated NICs.\n");
 162                         xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
 163                 }
 164                 if (xen_must_unplug_disks()) {
 165                         pr_info("Blkfront and the Xen platform PCI driver have "
 166                                         "been compiled for this kernel: unplug emulated disks.\n"
 167                                         "You might have to change the root device\n"
 168                                         "from /dev/hd[a-d] to /dev/xvd[a-d]\n"
 169                                         "in your root= kernel command line option\n");
 170                         xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
 171                 }
 172         }
 173         /* Now unplug the emulated devices */
 174         if (!(xen_emul_unplug & XEN_UNPLUG_UNNECESSARY))
 175                 outw(xen_emul_unplug, XEN_IOPORT_UNPLUG);
 176         xen_platform_pci_unplug = xen_emul_unplug;
 177 }
 178
 179 static int __init parse_xen_emul_unplug(char *arg)
 180 {
 181         char *p, *q;
 182         int l;
 183
 184         for (p = arg; p; p = q) {
 185                 q = strchr(p, ',');
 186                 if (q) {
 187                         l = q - p;
 188                         q++;
 189                 } else {
 190                         l = strlen(p);
 191                 }
 192                 if (!strncmp(p, "all", l))
 193                         xen_emul_unplug |= XEN_UNPLUG_ALL;
 194                 else if (!strncmp(p, "ide-disks", l))
 195                         xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
 196                 else if (!strncmp(p, "aux-ide-disks", l))
 197                         xen_emul_unplug |= XEN_UNPLUG_AUX_IDE_DISKS;
 198                 else if (!strncmp(p, "nics", l))
 199                         xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
 200                 else if (!strncmp(p, "unnecessary", l))
 201                         xen_emul_unplug |= XEN_UNPLUG_UNNECESSARY;
 202                 else if (!strncmp(p, "never", l))
 203                         xen_emul_unplug |= XEN_UNPLUG_NEVER;
 204                 else
 205                         pr_warn("unrecognised option '%s' "
 206                                  "in parameter 'xen_emul_unplug'\n", p);
 207         }
 208         return 0;
 209 }
 210 early_param("xen_emul_unplug", parse_xen_emul_unplug);