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 <asm/div64.h>
  26#include <asm/vmware.h>
  27#include <asm/x86_init.h>
  28
  29#define CPUID_VMWARE_INFO_LEAF  0x40000000
  30#define VMWARE_HYPERVISOR_MAGIC 0x564D5868
  31#define VMWARE_HYPERVISOR_PORT  0x5658
  32
  33#define VMWARE_PORT_CMD_GETVERSION      10
  34#define VMWARE_PORT_CMD_GETHZ           45
  35
  36#define VMWARE_PORT(cmd, eax, ebx, ecx, edx)                            \
  37        __asm__("inl (%%dx)" :                                          \
  38                        "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :    \
  39                        "0"(VMWARE_HYPERVISOR_MAGIC),                   \
  40                        "1"(VMWARE_PORT_CMD_##cmd),                     \
  41                        "2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :    \
  42                        "memory");
  43
  44static inline int __vmware_platform(void)
  45{
  46        uint32_t eax, ebx, ecx, edx;
  47        VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
  48        return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
  49}
  50
  51static unsigned long vmware_get_tsc_khz(void)
  52{
  53        uint64_t tsc_hz;
  54        uint32_t eax, ebx, ecx, edx;
  55
  56        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  57
  58        tsc_hz = eax | (((uint64_t)ebx) << 32);
  59        do_div(tsc_hz, 1000);
  60        BUG_ON(tsc_hz >> 32);
  61        printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
  62                         (unsigned long) tsc_hz / 1000,
  63                         (unsigned long) tsc_hz % 1000);
  64        return tsc_hz;
  65}
  66
  67void __init vmware_platform_setup(void)
  68{
  69        uint32_t eax, ebx, ecx, edx;
  70
  71        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  72
  73        if (ebx != UINT_MAX)
  74                x86_platform.calibrate_tsc = vmware_get_tsc_khz;
  75        else
  76                printk(KERN_WARNING
  77                       "Failed to get TSC freq from the hypervisor\n");
  78}
  79
  80/*
  81 * While checking the dmi string infomation, just checking the product
  82 * serial key should be enough, as this will always have a VMware
  83 * specific string when running under VMware hypervisor.
  84 */
  85int vmware_platform(void)
  86{
  87        if (cpu_has_hypervisor) {
  88                unsigned int eax, ebx, ecx, edx;
  89                char hyper_vendor_id[13];
  90
  91                cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &ebx, &ecx, &edx);
  92                memcpy(hyper_vendor_id + 0, &ebx, 4);
  93                memcpy(hyper_vendor_id + 4, &ecx, 4);
  94                memcpy(hyper_vendor_id + 8, &edx, 4);
  95                hyper_vendor_id[12] = '\0';
  96                if (!strcmp(hyper_vendor_id, "VMwareVMware"))
  97                        return 1;
  98        } else if (dmi_available && dmi_name_in_serial("VMware") &&
  99                   __vmware_platform())
 100                return 1;
 101
 102        return 0;
 103}
 104
 105/*
 106 * VMware hypervisor takes care of exporting a reliable TSC to the guest.
 107 * Still, due to timing difference when running on virtual cpus, the TSC can
 108 * be marked as unstable in some cases. For example, the TSC sync check at
 109 * bootup can fail due to a marginal offset between vcpus' TSCs (though the
 110 * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
 111 * is not suitable as a watchdog when running on a hypervisor because the
 112 * kernel may miss a wrap of the counter if the vcpu is descheduled for a
 113 * long time. To skip these checks at runtime we set these capability bits,
 114 * so that the kernel could just trust the hypervisor with providing a
 115 * reliable virtual TSC that is suitable for timekeeping.
 116 */
 117void __cpuinit vmware_set_feature_bits(struct cpuinfo_x86 *c)
 118{
 119        set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 120        set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE);
 121}
 122