xref: /openbmc/linux/arch/x86/kernel/cpu/vmware.c (revision 32ced09d)
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 #include <asm/vmware.h>
34 
35 #undef pr_fmt
36 #define pr_fmt(fmt)	"vmware: " fmt
37 
38 #define CPUID_VMWARE_INFO_LEAF               0x40000000
39 #define CPUID_VMWARE_FEATURES_LEAF           0x40000010
40 #define CPUID_VMWARE_FEATURES_ECX_VMMCALL    BIT(0)
41 #define CPUID_VMWARE_FEATURES_ECX_VMCALL     BIT(1)
42 
43 #define VMWARE_HYPERVISOR_MAGIC	0x564D5868
44 
45 #define VMWARE_CMD_GETVERSION    10
46 #define VMWARE_CMD_GETHZ         45
47 #define VMWARE_CMD_GETVCPU_INFO  68
48 #define VMWARE_CMD_LEGACY_X2APIC  3
49 #define VMWARE_CMD_VCPU_RESERVED 31
50 
51 #define VMWARE_PORT(cmd, eax, ebx, ecx, edx)				\
52 	__asm__("inl (%%dx), %%eax" :					\
53 		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
54 		"a"(VMWARE_HYPERVISOR_MAGIC),				\
55 		"c"(VMWARE_CMD_##cmd),					\
56 		"d"(VMWARE_HYPERVISOR_PORT), "b"(UINT_MAX) :		\
57 		"memory")
58 
59 #define VMWARE_VMCALL(cmd, eax, ebx, ecx, edx)				\
60 	__asm__("vmcall" :						\
61 		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
62 		"a"(VMWARE_HYPERVISOR_MAGIC),				\
63 		"c"(VMWARE_CMD_##cmd),					\
64 		"d"(0), "b"(UINT_MAX) :					\
65 		"memory")
66 
67 #define VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx)                         \
68 	__asm__("vmmcall" :						\
69 		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
70 		"a"(VMWARE_HYPERVISOR_MAGIC),				\
71 		"c"(VMWARE_CMD_##cmd),					\
72 		"d"(0), "b"(UINT_MAX) :					\
73 		"memory")
74 
75 #define VMWARE_CMD(cmd, eax, ebx, ecx, edx) do {		\
76 	switch (vmware_hypercall_mode) {			\
77 	case CPUID_VMWARE_FEATURES_ECX_VMCALL:			\
78 		VMWARE_VMCALL(cmd, eax, ebx, ecx, edx);		\
79 		break;						\
80 	case CPUID_VMWARE_FEATURES_ECX_VMMCALL:			\
81 		VMWARE_VMMCALL(cmd, eax, ebx, ecx, edx);	\
82 		break;						\
83 	default:						\
84 		VMWARE_PORT(cmd, eax, ebx, ecx, edx);		\
85 		break;						\
86 	}							\
87 	} while (0)
88 
89 static unsigned long vmware_tsc_khz __ro_after_init;
90 static u8 vmware_hypercall_mode     __ro_after_init;
91 
92 static inline int __vmware_platform(void)
93 {
94 	uint32_t eax, ebx, ecx, edx;
95 	VMWARE_CMD(GETVERSION, eax, ebx, ecx, edx);
96 	return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
97 }
98 
99 static unsigned long vmware_get_tsc_khz(void)
100 {
101 	return vmware_tsc_khz;
102 }
103 
104 #ifdef CONFIG_PARAVIRT
105 static struct cyc2ns_data vmware_cyc2ns __ro_after_init;
106 static int vmw_sched_clock __initdata = 1;
107 
108 static __init int setup_vmw_sched_clock(char *s)
109 {
110 	vmw_sched_clock = 0;
111 	return 0;
112 }
113 early_param("no-vmw-sched-clock", setup_vmw_sched_clock);
114 
115 static unsigned long long notrace vmware_sched_clock(void)
116 {
117 	unsigned long long ns;
118 
119 	ns = mul_u64_u32_shr(rdtsc(), vmware_cyc2ns.cyc2ns_mul,
120 			     vmware_cyc2ns.cyc2ns_shift);
121 	ns -= vmware_cyc2ns.cyc2ns_offset;
122 	return ns;
123 }
124 
125 static void __init vmware_sched_clock_setup(void)
126 {
127 	struct cyc2ns_data *d = &vmware_cyc2ns;
128 	unsigned long long tsc_now = rdtsc();
129 
130 	clocks_calc_mult_shift(&d->cyc2ns_mul, &d->cyc2ns_shift,
131 			       vmware_tsc_khz, NSEC_PER_MSEC, 0);
132 	d->cyc2ns_offset = mul_u64_u32_shr(tsc_now, d->cyc2ns_mul,
133 					   d->cyc2ns_shift);
134 
135 	pv_ops.time.sched_clock = vmware_sched_clock;
136 	pr_info("using sched offset of %llu ns\n", d->cyc2ns_offset);
137 }
138 
139 static void __init vmware_paravirt_ops_setup(void)
140 {
141 	pv_info.name = "VMware hypervisor";
142 	pv_ops.cpu.io_delay = paravirt_nop;
143 
144 	if (vmware_tsc_khz && vmw_sched_clock)
145 		vmware_sched_clock_setup();
146 }
147 #else
148 #define vmware_paravirt_ops_setup() do {} while (0)
149 #endif
150 
151 /*
152  * VMware hypervisor takes care of exporting a reliable TSC to the guest.
153  * Still, due to timing difference when running on virtual cpus, the TSC can
154  * be marked as unstable in some cases. For example, the TSC sync check at
155  * bootup can fail due to a marginal offset between vcpus' TSCs (though the
156  * TSCs do not drift from each other).  Also, the ACPI PM timer clocksource
157  * is not suitable as a watchdog when running on a hypervisor because the
158  * kernel may miss a wrap of the counter if the vcpu is descheduled for a
159  * long time. To skip these checks at runtime we set these capability bits,
160  * so that the kernel could just trust the hypervisor with providing a
161  * reliable virtual TSC that is suitable for timekeeping.
162  */
163 static void __init vmware_set_capabilities(void)
164 {
165 	setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
166 	setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
167 	if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMCALL)
168 		setup_force_cpu_cap(X86_FEATURE_VMCALL);
169 	else if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMMCALL)
170 		setup_force_cpu_cap(X86_FEATURE_VMW_VMMCALL);
171 }
172 
173 static void __init vmware_platform_setup(void)
174 {
175 	uint32_t eax, ebx, ecx, edx;
176 	uint64_t lpj, tsc_khz;
177 
178 	VMWARE_CMD(GETHZ, eax, ebx, ecx, edx);
179 
180 	if (ebx != UINT_MAX) {
181 		lpj = tsc_khz = eax | (((uint64_t)ebx) << 32);
182 		do_div(tsc_khz, 1000);
183 		WARN_ON(tsc_khz >> 32);
184 		pr_info("TSC freq read from hypervisor : %lu.%03lu MHz\n",
185 			(unsigned long) tsc_khz / 1000,
186 			(unsigned long) tsc_khz % 1000);
187 
188 		if (!preset_lpj) {
189 			do_div(lpj, HZ);
190 			preset_lpj = lpj;
191 		}
192 
193 		vmware_tsc_khz = tsc_khz;
194 		x86_platform.calibrate_tsc = vmware_get_tsc_khz;
195 		x86_platform.calibrate_cpu = vmware_get_tsc_khz;
196 
197 #ifdef CONFIG_X86_LOCAL_APIC
198 		/* Skip lapic calibration since we know the bus frequency. */
199 		lapic_timer_period = ecx / HZ;
200 		pr_info("Host bus clock speed read from hypervisor : %u Hz\n",
201 			ecx);
202 #endif
203 	} else {
204 		pr_warn("Failed to get TSC freq from the hypervisor\n");
205 	}
206 
207 	vmware_paravirt_ops_setup();
208 
209 #ifdef CONFIG_X86_IO_APIC
210 	no_timer_check = 1;
211 #endif
212 
213 	vmware_set_capabilities();
214 }
215 
216 static u8 vmware_select_hypercall(void)
217 {
218 	int eax, ebx, ecx, edx;
219 
220 	cpuid(CPUID_VMWARE_FEATURES_LEAF, &eax, &ebx, &ecx, &edx);
221 	return (ecx & (CPUID_VMWARE_FEATURES_ECX_VMMCALL |
222 		       CPUID_VMWARE_FEATURES_ECX_VMCALL));
223 }
224 
225 /*
226  * While checking the dmi string information, just checking the product
227  * serial key should be enough, as this will always have a VMware
228  * specific string when running under VMware hypervisor.
229  * If !boot_cpu_has(X86_FEATURE_HYPERVISOR), vmware_hypercall_mode
230  * intentionally defaults to 0.
231  */
232 static uint32_t __init vmware_platform(void)
233 {
234 	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
235 		unsigned int eax;
236 		unsigned int hyper_vendor_id[3];
237 
238 		cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
239 		      &hyper_vendor_id[1], &hyper_vendor_id[2]);
240 		if (!memcmp(hyper_vendor_id, "VMwareVMware", 12)) {
241 			if (eax >= CPUID_VMWARE_FEATURES_LEAF)
242 				vmware_hypercall_mode =
243 					vmware_select_hypercall();
244 
245 			pr_info("hypercall mode: 0x%02x\n",
246 				(unsigned int) vmware_hypercall_mode);
247 
248 			return CPUID_VMWARE_INFO_LEAF;
249 		}
250 	} else if (dmi_available && dmi_name_in_serial("VMware") &&
251 		   __vmware_platform())
252 		return 1;
253 
254 	return 0;
255 }
256 
257 /* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */
258 static bool __init vmware_legacy_x2apic_available(void)
259 {
260 	uint32_t eax, ebx, ecx, edx;
261 	VMWARE_CMD(GETVCPU_INFO, eax, ebx, ecx, edx);
262 	return (eax & (1 << VMWARE_CMD_VCPU_RESERVED)) == 0 &&
263 	       (eax & (1 << VMWARE_CMD_LEGACY_X2APIC)) != 0;
264 }
265 
266 const __initconst struct hypervisor_x86 x86_hyper_vmware = {
267 	.name			= "VMware",
268 	.detect			= vmware_platform,
269 	.type			= X86_HYPER_VMWARE,
270 	.init.init_platform	= vmware_platform_setup,
271 	.init.x2apic_available	= vmware_legacy_x2apic_available,
272 };
273