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 #define VMWARE_PORT_CMD_GETVCPU_INFO    68
  37 #define VMWARE_PORT_CMD_LEGACY_X2APIC   3
  38 #define VMWARE_PORT_CMD_VCPU_RESERVED   31
  39
  40 #define VMWARE_PORT(cmd, eax, ebx, ecx, edx)                            \
  41         __asm__("inl (%%dx)" :                                          \
  42                         "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :    \
  43                         "0"(VMWARE_HYPERVISOR_MAGIC),                   \
  44                         "1"(VMWARE_PORT_CMD_##cmd),                     \
  45                         "2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :    \
  46                         "memory");
  47
  48 static inline int __vmware_platform(void)
  49 {
  50         uint32_t eax, ebx, ecx, edx;
  51         VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
  52         return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
  53 }
  54
  55 static unsigned long vmware_get_tsc_khz(void)
  56 {
  57         uint64_t tsc_hz, lpj;
  58         uint32_t eax, ebx, ecx, edx;
  59
  60         VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  61
  62         tsc_hz = eax | (((uint64_t)ebx) << 32);
  63         do_div(tsc_hz, 1000);
  64         BUG_ON(tsc_hz >> 32);
  65         pr_info("TSC freq read from hypervisor : %lu.%03lu MHz\n",
  66                          (unsigned long) tsc_hz / 1000,
  67                          (unsigned long) tsc_hz % 1000);
  68
  69         if (!preset_lpj) {
  70                 lpj = ((u64)tsc_hz * 1000);
  71                 do_div(lpj, HZ);
  72                 preset_lpj = lpj;
  73         }
  74
  75         return tsc_hz;
  76 }
  77
  78 static void __init vmware_platform_setup(void)
  79 {
  80         uint32_t eax, ebx, ecx, edx;
  81
  82         VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
  83
  84         if (ebx != UINT_MAX)
  85                 x86_platform.calibrate_tsc = vmware_get_tsc_khz;
  86         else
  87                 pr_warn("Failed to get TSC freq from the hypervisor\n");
  88 }
  89
  90 /*
  91  * While checking the dmi string information, just checking the product
  92  * serial key should be enough, as this will always have a VMware
  93  * specific string when running under VMware hypervisor.
  94  */
  95 static uint32_t __init vmware_platform(void)
  96 {
  97         if (cpu_has_hypervisor) {
  98                 unsigned int eax;
  99                 unsigned int hyper_vendor_id[3];
 100
 101                 cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
 102                       &hyper_vendor_id[1], &hyper_vendor_id[2]);
 103                 if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
 104                         return CPUID_VMWARE_INFO_LEAF;
 105         } else if (dmi_available && dmi_name_in_serial("VMware") &&
 106                    __vmware_platform())
 107                 return 1;
 108
 109         return 0;
 110 }
 111
 112 /*
 113  * VMware hypervisor takes care of exporting a reliable TSC to the guest.
 114  * Still, due to timing difference when running on virtual cpus, the TSC can
 115  * be marked as unstable in some cases. For example, the TSC sync check at
 116  * bootup can fail due to a marginal offset between vcpus' TSCs (though the
 117  * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
 118  * is not suitable as a watchdog when running on a hypervisor because the
 119  * kernel may miss a wrap of the counter if the vcpu is descheduled for a
 120  * long time. To skip these checks at runtime we set these capability bits,
 121  * so that the kernel could just trust the hypervisor with providing a
 122  * reliable virtual TSC that is suitable for timekeeping.
 123  */
 124 static void vmware_set_cpu_features(struct cpuinfo_x86 *c)
 125 {
 126         set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 127         set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE);
 128 }
 129
 130 /* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */
 131 static bool __init vmware_legacy_x2apic_available(void)
 132 {
 133         uint32_t eax, ebx, ecx, edx;
 134         VMWARE_PORT(GETVCPU_INFO, eax, ebx, ecx, edx);
 135         return (eax & (1 << VMWARE_PORT_CMD_VCPU_RESERVED)) == 0 &&
 136                (eax & (1 << VMWARE_PORT_CMD_LEGACY_X2APIC)) != 0;
 137 }
 138
 139 const __refconst struct hypervisor_x86 x86_hyper_vmware = {
 140         .name                   = "VMware",
 141         .detect                 = vmware_platform,
 142         .set_cpu_features       = vmware_set_cpu_features,
 143         .init_platform          = vmware_platform_setup,
 144         .x2apic_available       = vmware_legacy_x2apic_available,
 145 };
 146 EXPORT_SYMBOL(x86_hyper_vmware);