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1/* KVM paravirtual clock driver. A clocksource implementation
2 Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
17*/
18
19#include <linux/clocksource.h>
20#include <linux/kvm_para.h>
21#include <asm/pvclock.h>
22#include <asm/msr.h>
23#include <asm/apic.h>
24#include <linux/percpu.h>
25
26#include <asm/x86_init.h>
27#include <asm/reboot.h>
28
29static int kvmclock = 1;
30static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
31static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
32
33static int parse_no_kvmclock(char *arg)
34{
35 kvmclock = 0;
36 return 0;
37}
38early_param("no-kvmclock", parse_no_kvmclock);
39
40/* The hypervisor will put information about time periodically here */
41static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock);
42static struct pvclock_wall_clock wall_clock;
43
44/*
45 * The wallclock is the time of day when we booted. Since then, some time may
46 * have elapsed since the hypervisor wrote the data. So we try to account for
47 * that with system time
48 */
49static unsigned long kvm_get_wallclock(void)
50{
51 struct pvclock_vcpu_time_info *vcpu_time;
52 struct timespec ts;
53 int low, high;
54
55 low = (int)__pa_symbol(&wall_clock);
56 high = ((u64)__pa_symbol(&wall_clock) >> 32);
57
58 native_write_msr(msr_kvm_wall_clock, low, high);
59
60 vcpu_time = &get_cpu_var(hv_clock);
61 pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
62 put_cpu_var(hv_clock);
63
64 return ts.tv_sec;
65}
66
67static int kvm_set_wallclock(unsigned long now)
68{
69 return -1;
70}
71
72static cycle_t kvm_clock_read(void)
73{
74 struct pvclock_vcpu_time_info *src;
75 cycle_t ret;
76
77 src = &get_cpu_var(hv_clock);
78 ret = pvclock_clocksource_read(src);
79 put_cpu_var(hv_clock);
80 return ret;
81}
82
83static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
84{
85 return kvm_clock_read();
86}
87
88/*
89 * If we don't do that, there is the possibility that the guest
90 * will calibrate under heavy load - thus, getting a lower lpj -
91 * and execute the delays themselves without load. This is wrong,
92 * because no delay loop can finish beforehand.
93 * Any heuristics is subject to fail, because ultimately, a large
94 * poll of guests can be running and trouble each other. So we preset
95 * lpj here
96 */
97static unsigned long kvm_get_tsc_khz(void)
98{
99 struct pvclock_vcpu_time_info *src;
100 src = &per_cpu(hv_clock, 0);
101 return pvclock_tsc_khz(src);
102}
103
104static void kvm_get_preset_lpj(void)
105{
106 unsigned long khz;
107 u64 lpj;
108
109 khz = kvm_get_tsc_khz();
110
111 lpj = ((u64)khz * 1000);
112 do_div(lpj, HZ);
113 preset_lpj = lpj;
114}
115
116static struct clocksource kvm_clock = {
117 .name = "kvm-clock",
118 .read = kvm_clock_get_cycles,
119 .rating = 400,
120 .mask = CLOCKSOURCE_MASK(64),
121 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
122};
123
124int kvm_register_clock(char *txt)
125{
126 int cpu = smp_processor_id();
127 int low, high, ret;
128
129 low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1;
130 high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32);
131 ret = native_write_msr_safe(msr_kvm_system_time, low, high);
132 printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
133 cpu, high, low, txt);
134
135 return ret;
136}
137
138#ifdef CONFIG_X86_LOCAL_APIC
139static void __cpuinit kvm_setup_secondary_clock(void)
140{
141 /*
142 * Now that the first cpu already had this clocksource initialized,
143 * we shouldn't fail.
144 */
145 WARN_ON(kvm_register_clock("secondary cpu clock"));
146 /* ok, done with our trickery, call native */
147 setup_secondary_APIC_clock();
148}
149#endif
150
151/*
152 * After the clock is registered, the host will keep writing to the
153 * registered memory location. If the guest happens to shutdown, this memory
154 * won't be valid. In cases like kexec, in which you install a new kernel, this
155 * means a random memory location will be kept being written. So before any
156 * kind of shutdown from our side, we unregister the clock by writting anything
157 * that does not have the 'enable' bit set in the msr
158 */
159#ifdef CONFIG_KEXEC
160static void kvm_crash_shutdown(struct pt_regs *regs)
161{
162 native_write_msr(msr_kvm_system_time, 0, 0);
163 kvm_disable_steal_time();
164 native_machine_crash_shutdown(regs);
165}
166#endif
167
168static void kvm_shutdown(void)
169{
170 native_write_msr(msr_kvm_system_time, 0, 0);
171 kvm_disable_steal_time();
172 native_machine_shutdown();
173}
174
175void __init kvmclock_init(void)
176{
177 if (!kvm_para_available())
178 return;
179
180 if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
181 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
182 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
183 } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
184 return;
185
186 printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
187 msr_kvm_system_time, msr_kvm_wall_clock);
188
189 if (kvm_register_clock("boot clock"))
190 return;
191 pv_time_ops.sched_clock = kvm_clock_read;
192 x86_platform.calibrate_tsc = kvm_get_tsc_khz;
193 x86_platform.get_wallclock = kvm_get_wallclock;
194 x86_platform.set_wallclock = kvm_set_wallclock;
195#ifdef CONFIG_X86_LOCAL_APIC
196 x86_cpuinit.setup_percpu_clockev =
197 kvm_setup_secondary_clock;
198#endif
199 machine_ops.shutdown = kvm_shutdown;
200#ifdef CONFIG_KEXEC
201 machine_ops.crash_shutdown = kvm_crash_shutdown;
202#endif
203 kvm_get_preset_lpj();
204 clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
205 pv_info.paravirt_enabled = 1;
206 pv_info.name = "KVM";
207
208 if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
209 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
210}
1/* KVM paravirtual clock driver. A clocksource implementation
2 Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
17*/
18
19#include <linux/clocksource.h>
20#include <linux/kvm_para.h>
21#include <asm/pvclock.h>
22#include <asm/msr.h>
23#include <asm/apic.h>
24#include <linux/percpu.h>
25#include <linux/hardirq.h>
26#include <linux/memblock.h>
27#include <linux/sched.h>
28
29#include <asm/x86_init.h>
30#include <asm/reboot.h>
31
32static int kvmclock = 1;
33static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
34static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
35static cycle_t kvm_sched_clock_offset;
36
37static int parse_no_kvmclock(char *arg)
38{
39 kvmclock = 0;
40 return 0;
41}
42early_param("no-kvmclock", parse_no_kvmclock);
43
44/* The hypervisor will put information about time periodically here */
45static struct pvclock_vsyscall_time_info *hv_clock;
46static struct pvclock_wall_clock wall_clock;
47
48struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
49{
50 return hv_clock;
51}
52
53/*
54 * The wallclock is the time of day when we booted. Since then, some time may
55 * have elapsed since the hypervisor wrote the data. So we try to account for
56 * that with system time
57 */
58static void kvm_get_wallclock(struct timespec *now)
59{
60 struct pvclock_vcpu_time_info *vcpu_time;
61 int low, high;
62 int cpu;
63
64 low = (int)__pa_symbol(&wall_clock);
65 high = ((u64)__pa_symbol(&wall_clock) >> 32);
66
67 native_write_msr(msr_kvm_wall_clock, low, high);
68
69 cpu = get_cpu();
70
71 vcpu_time = &hv_clock[cpu].pvti;
72 pvclock_read_wallclock(&wall_clock, vcpu_time, now);
73
74 put_cpu();
75}
76
77static int kvm_set_wallclock(const struct timespec *now)
78{
79 return -1;
80}
81
82static cycle_t kvm_clock_read(void)
83{
84 struct pvclock_vcpu_time_info *src;
85 cycle_t ret;
86 int cpu;
87
88 preempt_disable_notrace();
89 cpu = smp_processor_id();
90 src = &hv_clock[cpu].pvti;
91 ret = pvclock_clocksource_read(src);
92 preempt_enable_notrace();
93 return ret;
94}
95
96static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
97{
98 return kvm_clock_read();
99}
100
101static cycle_t kvm_sched_clock_read(void)
102{
103 return kvm_clock_read() - kvm_sched_clock_offset;
104}
105
106static inline void kvm_sched_clock_init(bool stable)
107{
108 if (!stable) {
109 pv_time_ops.sched_clock = kvm_clock_read;
110 return;
111 }
112
113 kvm_sched_clock_offset = kvm_clock_read();
114 pv_time_ops.sched_clock = kvm_sched_clock_read;
115 set_sched_clock_stable();
116
117 printk(KERN_INFO "kvm-clock: using sched offset of %llu cycles\n",
118 kvm_sched_clock_offset);
119
120 BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) >
121 sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time));
122}
123
124/*
125 * If we don't do that, there is the possibility that the guest
126 * will calibrate under heavy load - thus, getting a lower lpj -
127 * and execute the delays themselves without load. This is wrong,
128 * because no delay loop can finish beforehand.
129 * Any heuristics is subject to fail, because ultimately, a large
130 * poll of guests can be running and trouble each other. So we preset
131 * lpj here
132 */
133static unsigned long kvm_get_tsc_khz(void)
134{
135 struct pvclock_vcpu_time_info *src;
136 int cpu;
137 unsigned long tsc_khz;
138
139 cpu = get_cpu();
140 src = &hv_clock[cpu].pvti;
141 tsc_khz = pvclock_tsc_khz(src);
142 put_cpu();
143 return tsc_khz;
144}
145
146static void kvm_get_preset_lpj(void)
147{
148 unsigned long khz;
149 u64 lpj;
150
151 khz = kvm_get_tsc_khz();
152
153 lpj = ((u64)khz * 1000);
154 do_div(lpj, HZ);
155 preset_lpj = lpj;
156}
157
158bool kvm_check_and_clear_guest_paused(void)
159{
160 bool ret = false;
161 struct pvclock_vcpu_time_info *src;
162 int cpu = smp_processor_id();
163
164 if (!hv_clock)
165 return ret;
166
167 src = &hv_clock[cpu].pvti;
168 if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
169 src->flags &= ~PVCLOCK_GUEST_STOPPED;
170 pvclock_touch_watchdogs();
171 ret = true;
172 }
173
174 return ret;
175}
176
177static struct clocksource kvm_clock = {
178 .name = "kvm-clock",
179 .read = kvm_clock_get_cycles,
180 .rating = 400,
181 .mask = CLOCKSOURCE_MASK(64),
182 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
183};
184
185int kvm_register_clock(char *txt)
186{
187 int cpu = smp_processor_id();
188 int low, high, ret;
189 struct pvclock_vcpu_time_info *src;
190
191 if (!hv_clock)
192 return 0;
193
194 src = &hv_clock[cpu].pvti;
195 low = (int)slow_virt_to_phys(src) | 1;
196 high = ((u64)slow_virt_to_phys(src) >> 32);
197 ret = native_write_msr_safe(msr_kvm_system_time, low, high);
198 printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
199 cpu, high, low, txt);
200
201 return ret;
202}
203
204static void kvm_save_sched_clock_state(void)
205{
206}
207
208static void kvm_restore_sched_clock_state(void)
209{
210 kvm_register_clock("primary cpu clock, resume");
211}
212
213#ifdef CONFIG_X86_LOCAL_APIC
214static void kvm_setup_secondary_clock(void)
215{
216 /*
217 * Now that the first cpu already had this clocksource initialized,
218 * we shouldn't fail.
219 */
220 WARN_ON(kvm_register_clock("secondary cpu clock"));
221}
222#endif
223
224/*
225 * After the clock is registered, the host will keep writing to the
226 * registered memory location. If the guest happens to shutdown, this memory
227 * won't be valid. In cases like kexec, in which you install a new kernel, this
228 * means a random memory location will be kept being written. So before any
229 * kind of shutdown from our side, we unregister the clock by writing anything
230 * that does not have the 'enable' bit set in the msr
231 */
232#ifdef CONFIG_KEXEC_CORE
233static void kvm_crash_shutdown(struct pt_regs *regs)
234{
235 native_write_msr(msr_kvm_system_time, 0, 0);
236 kvm_disable_steal_time();
237 native_machine_crash_shutdown(regs);
238}
239#endif
240
241static void kvm_shutdown(void)
242{
243 native_write_msr(msr_kvm_system_time, 0, 0);
244 kvm_disable_steal_time();
245 native_machine_shutdown();
246}
247
248void __init kvmclock_init(void)
249{
250 struct pvclock_vcpu_time_info *vcpu_time;
251 unsigned long mem;
252 int size, cpu;
253 u8 flags;
254
255 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
256
257 if (!kvm_para_available())
258 return;
259
260 if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
261 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
262 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
263 } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
264 return;
265
266 printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
267 msr_kvm_system_time, msr_kvm_wall_clock);
268
269 mem = memblock_alloc(size, PAGE_SIZE);
270 if (!mem)
271 return;
272 hv_clock = __va(mem);
273 memset(hv_clock, 0, size);
274
275 if (kvm_register_clock("primary cpu clock")) {
276 hv_clock = NULL;
277 memblock_free(mem, size);
278 return;
279 }
280
281 if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
282 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
283
284 cpu = get_cpu();
285 vcpu_time = &hv_clock[cpu].pvti;
286 flags = pvclock_read_flags(vcpu_time);
287
288 kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT);
289 put_cpu();
290
291 x86_platform.calibrate_tsc = kvm_get_tsc_khz;
292 x86_platform.get_wallclock = kvm_get_wallclock;
293 x86_platform.set_wallclock = kvm_set_wallclock;
294#ifdef CONFIG_X86_LOCAL_APIC
295 x86_cpuinit.early_percpu_clock_init =
296 kvm_setup_secondary_clock;
297#endif
298 x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
299 x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
300 machine_ops.shutdown = kvm_shutdown;
301#ifdef CONFIG_KEXEC_CORE
302 machine_ops.crash_shutdown = kvm_crash_shutdown;
303#endif
304 kvm_get_preset_lpj();
305 clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
306 pv_info.name = "KVM";
307}
308
309int __init kvm_setup_vsyscall_timeinfo(void)
310{
311#ifdef CONFIG_X86_64
312 int cpu;
313 u8 flags;
314 struct pvclock_vcpu_time_info *vcpu_time;
315 unsigned int size;
316
317 if (!hv_clock)
318 return 0;
319
320 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
321
322 cpu = get_cpu();
323
324 vcpu_time = &hv_clock[cpu].pvti;
325 flags = pvclock_read_flags(vcpu_time);
326
327 if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
328 put_cpu();
329 return 1;
330 }
331
332 put_cpu();
333
334 kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
335#endif
336 return 0;
337}