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
  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
  45 static 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
  52 static 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
  75 static 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  */
  93 static 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  */
 122 static 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
 128 const __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 };
 134 EXPORT_SYMBOL(x86_hyper_vmware);