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