LXR linux/arch/x86/kernel/cpu/vmware.c

   1/*
   2 * VMware Detection code.
   3 *
   4 * Copyright (C) 2008, VMware, Inc.
   5 * Author : Alok N Kataria <akataria@vmware.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful, but
  13 * WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  15 * NON INFRINGEMENT.  See the GNU General Public License for more
  16 * details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  21 *
  22 */
  23
  24#include <linux/dmi.h>
  25#include <linux/module.h>
  26#include <asm/div64.h>
  27#include <asm/x86_init.h>
  28#include <asm/hypervisor.h>
  29
  30#define CPUID_VMWARE_INFO_LEAF  0x40000000
  31#define VMWARE_HYPERVISOR_MAGIC 0x564D5868
  32#define VMWARE_HYPERVISOR_PORT  0x5658
  33
  34#define VMWARE_PORT_CMD_GETVERSION      10
  35#define VMWARE_PORT_CMD_GETHZ           45
  36#define VMWARE_PORT_CMD_GETVCPU_INFO    68
  37#define VMWARE_PORT_CMD_LEGACY_X2APIC   3
  38#define VMWARE_PORT_CMD_VCPU_RESERVED   31
  39
  40#define VMWARE_PORT(cmd, eax, ebx, ecx, edx)                            \
  41        __asm__("inl (%%dx)" :                                          \
  42                        "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :    \
  43                        "0"(VMWARE_HYPERVISOR_MAGIC),                   \
  44                        "1"(VMWARE_PORT_CMD_##cmd),                     \
  45                        "2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :    \
  46                        "memory");
  47
  48static inline int __vmware_platform(void)
  49{
  50        uint32_t eax, ebx, ecx, edx;
  51        VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
  52        return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
  53}
  54
  55static unsigned long vmware_get_tsc_khz(void)
  56{
  57        uint64_t tsc_hz, lpj;
  58        uint32_t eax, ebx, ecx, edx;
  59
  60        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  61
  62        tsc_hz = eax | (((uint64_t)ebx) << 32);
  63        do_div(tsc_hz, 1000);
  64        BUG_ON(tsc_hz >> 32);
  65        printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
  66                         (unsigned long) tsc_hz / 1000,
  67                         (unsigned long) tsc_hz % 1000);
  68
  69        if (!preset_lpj) {
  70                lpj = ((u64)tsc_hz * 1000);
  71                do_div(lpj, HZ);
  72                preset_lpj = lpj;
  73        }
  74
  75        return tsc_hz;
  76}
  77
  78static void __init vmware_platform_setup(void)
  79{
  80        uint32_t eax, ebx, ecx, edx;
  81
  82        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  83
  84        if (ebx != UINT_MAX)
  85                x86_platform.calibrate_tsc = vmware_get_tsc_khz;
  86        else
  87                printk(KERN_WARNING
  88                       "Failed to get TSC freq from the hypervisor\n");
  89}
  90
  91/*
  92 * While checking the dmi string information, just checking the product
  93 * serial key should be enough, as this will always have a VMware
  94 * specific string when running under VMware hypervisor.
  95 */
  96static uint32_t __init vmware_platform(void)
  97{
  98        if (cpu_has_hypervisor) {
  99                unsigned int eax;
 100                unsigned int hyper_vendor_id[3];
 101
 102                cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
 103                      &hyper_vendor_id[1], &hyper_vendor_id[2]);
 104                if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
 105                        return CPUID_VMWARE_INFO_LEAF;
 106        } else if (dmi_available && dmi_name_in_serial("VMware") &&
 107                   __vmware_platform())
 108                return 1;
 109
 110        return 0;
 111}
 112
 113/*
 114 * VMware hypervisor takes care of exporting a reliable TSC to the guest.
 115 * Still, due to timing difference when running on virtual cpus, the TSC can
 116 * be marked as unstable in some cases. For example, the TSC sync check at
 117 * bootup can fail due to a marginal offset between vcpus' TSCs (though the
 118 * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
 119 * is not suitable as a watchdog when running on a hypervisor because the
 120 * kernel may miss a wrap of the counter if the vcpu is descheduled for a
 121 * long time. To skip these checks at runtime we set these capability bits,
 122 * so that the kernel could just trust the hypervisor with providing a
 123 * reliable virtual TSC that is suitable for timekeeping.
 124 */
 125static void vmware_set_cpu_features(struct cpuinfo_x86 *c)
 126{
 127        set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 128        set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE);
 129}
 130
 131/* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */
 132static bool __init vmware_legacy_x2apic_available(void)
 133{
 134        uint32_t eax, ebx, ecx, edx;
 135        VMWARE_PORT(GETVCPU_INFO, eax, ebx, ecx, edx);
 136        return (eax & (1 << VMWARE_PORT_CMD_VCPU_RESERVED)) == 0 &&
 137               (eax & (1 << VMWARE_PORT_CMD_LEGACY_X2APIC)) != 0;
 138}
 139
 140const __refconst struct hypervisor_x86 x86_hyper_vmware = {
 141        .name                   = "VMware",
 142        .detect                 = vmware_platform,
 143        .set_cpu_features       = vmware_set_cpu_features,
 144        .init_platform          = vmware_platform_setup,
 145        .x2apic_available       = vmware_legacy_x2apic_available,
 146};
 147EXPORT_SYMBOL(x86_hyper_vmware);
 148