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 } 113