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
  44 static 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
  51 static 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
  67 void __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  */
  85 int 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  */
 117 void __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 }