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
__vmware_platform(void)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
vmware_get_tsc_khz(void)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
vmware_platform_setup(void)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 */
vmware_platform(void)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 */
vmware_set_cpu_features(struct cpuinfo_x86 * c)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);
135