linux/arch/x86/kernel/cpu/vmware.c
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   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
  37#define VMWARE_PORT(cmd, eax, ebx, ecx, edx)                            \
  38        __asm__("inl (%%dx)" :                                          \
  39                        "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :    \
  40                        "0"(VMWARE_HYPERVISOR_MAGIC),                   \
  41                        "1"(VMWARE_PORT_CMD_##cmd),                     \
  42                        "2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :    \
  43                        "memory");
  44
  45static inline int __vmware_platform(void)
  46{
  47        uint32_t eax, ebx, ecx, edx;
  48        VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
  49        return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
  50}
  51
  52static unsigned long vmware_get_tsc_khz(void)
  53{
  54        uint64_t tsc_hz, lpj;
  55        uint32_t eax, ebx, ecx, edx;
  56
  57        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  58
  59        tsc_hz = eax | (((uint64_t)ebx) << 32);
  60        do_div(tsc_hz, 1000);
  61        BUG_ON(tsc_hz >> 32);
  62        printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
  63                         (unsigned long) tsc_hz / 1000,
  64                         (unsigned long) tsc_hz % 1000);
  65
  66        if (!preset_lpj) {
  67                lpj = ((u64)tsc_hz * 1000);
  68                do_div(lpj, HZ);
  69                preset_lpj = lpj;
  70        }
  71
  72        return tsc_hz;
  73}
  74
  75static void __init vmware_platform_setup(void)
  76{
  77        uint32_t eax, ebx, ecx, edx;
  78
  79        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  80
  81        if (ebx != UINT_MAX)
  82                x86_platform.calibrate_tsc = vmware_get_tsc_khz;
  83        else
  84                printk(KERN_WARNING
  85                       "Failed to get TSC freq from the hypervisor\n");
  86}
  87
  88/*
  89 * While checking the dmi string information, just checking the product
  90 * serial key should be enough, as this will always have a VMware
  91 * specific string when running under VMware hypervisor.
  92 */
  93static bool __init vmware_platform(void)
  94{
  95        if (cpu_has_hypervisor) {
  96                unsigned int eax;
  97                unsigned int hyper_vendor_id[3];
  98
  99                cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
 100                      &hyper_vendor_id[1], &hyper_vendor_id[2]);
 101                if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
 102                        return true;
 103        } else if (dmi_available && dmi_name_in_serial("VMware") &&
 104                   __vmware_platform())
 105                return true;
 106
 107        return false;
 108}
 109
 110/*
 111 * VMware hypervisor takes care of exporting a reliable TSC to the guest.
 112 * Still, due to timing difference when running on virtual cpus, the TSC can
 113 * be marked as unstable in some cases. For example, the TSC sync check at
 114 * bootup can fail due to a marginal offset between vcpus' TSCs (though the
 115 * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
 116 * is not suitable as a watchdog when running on a hypervisor because the
 117 * kernel may miss a wrap of the counter if the vcpu is descheduled for a
 118 * long time. To skip these checks at runtime we set these capability bits,
 119 * so that the kernel could just trust the hypervisor with providing a
 120 * reliable virtual TSC that is suitable for timekeeping.
 121 */
 122static void __cpuinit vmware_set_cpu_features(struct cpuinfo_x86 *c)
 123{
 124        set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 125        set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE);
 126}
 127
 128const __refconst struct hypervisor_x86 x86_hyper_vmware = {
 129        .name                   = "VMware",
 130        .detect                 = vmware_platform,
 131        .set_cpu_features       = vmware_set_cpu_features,
 132        .init_platform          = vmware_platform_setup,
 133};
 134EXPORT_SYMBOL(x86_hyper_vmware);
 135
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