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/init.h>
  26#include <linux/export.h>
  27#include <linux/clocksource.h>
  28#include <asm/div64.h>
  29#include <asm/x86_init.h>
  30#include <asm/hypervisor.h>
  31#include <asm/timer.h>
  32#include <asm/apic.h>
  33
  34#undef pr_fmt
  35#define pr_fmt(fmt)     "vmware: " fmt
  36
  37#define CPUID_VMWARE_INFO_LEAF  0x40000000
  38#define VMWARE_HYPERVISOR_MAGIC 0x564D5868
  39#define VMWARE_HYPERVISOR_PORT  0x5658
  40
  41#define VMWARE_PORT_CMD_GETVERSION      10
  42#define VMWARE_PORT_CMD_GETHZ           45
  43#define VMWARE_PORT_CMD_GETVCPU_INFO    68
  44#define VMWARE_PORT_CMD_LEGACY_X2APIC   3
  45#define VMWARE_PORT_CMD_VCPU_RESERVED   31
  46
  47#define VMWARE_PORT(cmd, eax, ebx, ecx, edx)                            \
  48        __asm__("inl (%%dx)" :                                          \
  49                        "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :    \
  50                        "0"(VMWARE_HYPERVISOR_MAGIC),                   \
  51                        "1"(VMWARE_PORT_CMD_##cmd),                     \
  52                        "2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :    \
  53                        "memory");
  54
  55static unsigned long vmware_tsc_khz __ro_after_init;
  56
  57static inline int __vmware_platform(void)
  58{
  59        uint32_t eax, ebx, ecx, edx;
  60        VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
  61        return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
  62}
  63
  64static unsigned long vmware_get_tsc_khz(void)
  65{
  66        return vmware_tsc_khz;
  67}
  68
  69#ifdef CONFIG_PARAVIRT
  70static struct cyc2ns_data vmware_cyc2ns __ro_after_init;
  71static int vmw_sched_clock __initdata = 1;
  72
  73static __init int setup_vmw_sched_clock(char *s)
  74{
  75        vmw_sched_clock = 0;
  76        return 0;
  77}
  78early_param("no-vmw-sched-clock", setup_vmw_sched_clock);
  79
  80static unsigned long long vmware_sched_clock(void)
  81{
  82        unsigned long long ns;
  83
  84        ns = mul_u64_u32_shr(rdtsc(), vmware_cyc2ns.cyc2ns_mul,
  85                             vmware_cyc2ns.cyc2ns_shift);
  86        ns -= vmware_cyc2ns.cyc2ns_offset;
  87        return ns;
  88}
  89
  90static void __init vmware_sched_clock_setup(void)
  91{
  92        struct cyc2ns_data *d = &vmware_cyc2ns;
  93        unsigned long long tsc_now = rdtsc();
  94
  95        clocks_calc_mult_shift(&d->cyc2ns_mul, &d->cyc2ns_shift,
  96                               vmware_tsc_khz, NSEC_PER_MSEC, 0);
  97        d->cyc2ns_offset = mul_u64_u32_shr(tsc_now, d->cyc2ns_mul,
  98                                           d->cyc2ns_shift);
  99
 100        pv_time_ops.sched_clock = vmware_sched_clock;
 101        pr_info("using sched offset of %llu ns\n", d->cyc2ns_offset);
 102}
 103
 104static void __init vmware_paravirt_ops_setup(void)
 105{
 106        pv_info.name = "VMware hypervisor";
 107        pv_cpu_ops.io_delay = paravirt_nop;
 108
 109        if (vmware_tsc_khz && vmw_sched_clock)
 110                vmware_sched_clock_setup();
 111}
 112#else
 113#define vmware_paravirt_ops_setup() do {} while (0)
 114#endif
 115
 116/*
 117 * VMware hypervisor takes care of exporting a reliable TSC to the guest.
 118 * Still, due to timing difference when running on virtual cpus, the TSC can
 119 * be marked as unstable in some cases. For example, the TSC sync check at
 120 * bootup can fail due to a marginal offset between vcpus' TSCs (though the
 121 * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
 122 * is not suitable as a watchdog when running on a hypervisor because the
 123 * kernel may miss a wrap of the counter if the vcpu is descheduled for a
 124 * long time. To skip these checks at runtime we set these capability bits,
 125 * so that the kernel could just trust the hypervisor with providing a
 126 * reliable virtual TSC that is suitable for timekeeping.
 127 */
 128static void __init vmware_set_capabilities(void)
 129{
 130        setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
 131        setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 132}
 133
 134static void __init vmware_platform_setup(void)
 135{
 136        uint32_t eax, ebx, ecx, edx;
 137        uint64_t lpj, tsc_khz;
 138
 139        VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
 140
 141        if (ebx != UINT_MAX) {
 142                lpj = tsc_khz = eax | (((uint64_t)ebx) << 32);
 143                do_div(tsc_khz, 1000);
 144                WARN_ON(tsc_khz >> 32);
 145                pr_info("TSC freq read from hypervisor : %lu.%03lu MHz\n",
 146                        (unsigned long) tsc_khz / 1000,
 147                        (unsigned long) tsc_khz % 1000);
 148
 149                if (!preset_lpj) {
 150                        do_div(lpj, HZ);
 151                        preset_lpj = lpj;
 152                }
 153
 154                vmware_tsc_khz = tsc_khz;
 155                x86_platform.calibrate_tsc = vmware_get_tsc_khz;
 156                x86_platform.calibrate_cpu = vmware_get_tsc_khz;
 157
 158#ifdef CONFIG_X86_LOCAL_APIC
 159                /* Skip lapic calibration since we know the bus frequency. */
 160                lapic_timer_frequency = ecx / HZ;
 161                pr_info("Host bus clock speed read from hypervisor : %u Hz\n",
 162                        ecx);
 163#endif
 164        } else {
 165                pr_warn("Failed to get TSC freq from the hypervisor\n");
 166        }
 167
 168        vmware_paravirt_ops_setup();
 169
 170#ifdef CONFIG_X86_IO_APIC
 171        no_timer_check = 1;
 172#endif
 173
 174        vmware_set_capabilities();
 175}
 176
 177/*
 178 * While checking the dmi string information, just checking the product
 179 * serial key should be enough, as this will always have a VMware
 180 * specific string when running under VMware hypervisor.
 181 */
 182static uint32_t __init vmware_platform(void)
 183{
 184        if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
 185                unsigned int eax;
 186                unsigned int hyper_vendor_id[3];
 187
 188                cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
 189                      &hyper_vendor_id[1], &hyper_vendor_id[2]);
 190                if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
 191                        return CPUID_VMWARE_INFO_LEAF;
 192        } else if (dmi_available && dmi_name_in_serial("VMware") &&
 193                   __vmware_platform())
 194                return 1;
 195
 196        return 0;
 197}
 198
 199/* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */
 200static bool __init vmware_legacy_x2apic_available(void)
 201{
 202        uint32_t eax, ebx, ecx, edx;
 203        VMWARE_PORT(GETVCPU_INFO, eax, ebx, ecx, edx);
 204        return (eax & (1 << VMWARE_PORT_CMD_VCPU_RESERVED)) == 0 &&
 205               (eax & (1 << VMWARE_PORT_CMD_LEGACY_X2APIC)) != 0;
 206}
 207
 208const __initconst struct hypervisor_x86 x86_hyper_vmware = {
 209        .name                   = "VMware",
 210        .detect                 = vmware_platform,
 211        .type                   = X86_HYPER_VMWARE,
 212        .init.init_platform     = vmware_platform_setup,
 213        .init.x2apic_available  = vmware_legacy_x2apic_available,
 214};
 215