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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#include <linux/hardirq.h>
26
27#include <asm/x86_init.h>
28#include <asm/reboot.h>
29
30static int kvmclock = 1;
31static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
32static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
33
34static int parse_no_kvmclock(char *arg)
35{
36 kvmclock = 0;
37 return 0;
38}
39early_param("no-kvmclock", parse_no_kvmclock);
40
41/* The hypervisor will put information about time periodically here */
42static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock);
43static struct pvclock_wall_clock wall_clock;
44
45/*
46 * The wallclock is the time of day when we booted. Since then, some time may
47 * have elapsed since the hypervisor wrote the data. So we try to account for
48 * that with system time
49 */
50static unsigned long kvm_get_wallclock(void)
51{
52 struct pvclock_vcpu_time_info *vcpu_time;
53 struct timespec ts;
54 int low, high;
55
56 low = (int)__pa_symbol(&wall_clock);
57 high = ((u64)__pa_symbol(&wall_clock) >> 32);
58
59 native_write_msr(msr_kvm_wall_clock, low, high);
60
61 vcpu_time = &get_cpu_var(hv_clock);
62 pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
63 put_cpu_var(hv_clock);
64
65 return ts.tv_sec;
66}
67
68static int kvm_set_wallclock(unsigned long now)
69{
70 return -1;
71}
72
73static cycle_t kvm_clock_read(void)
74{
75 struct pvclock_vcpu_time_info *src;
76 cycle_t ret;
77
78 preempt_disable_notrace();
79 src = &__get_cpu_var(hv_clock);
80 ret = pvclock_clocksource_read(src);
81 preempt_enable_notrace();
82 return ret;
83}
84
85static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
86{
87 return kvm_clock_read();
88}
89
90/*
91 * If we don't do that, there is the possibility that the guest
92 * will calibrate under heavy load - thus, getting a lower lpj -
93 * and execute the delays themselves without load. This is wrong,
94 * because no delay loop can finish beforehand.
95 * Any heuristics is subject to fail, because ultimately, a large
96 * poll of guests can be running and trouble each other. So we preset
97 * lpj here
98 */
99static unsigned long kvm_get_tsc_khz(void)
100{
101 struct pvclock_vcpu_time_info *src;
102 src = &per_cpu(hv_clock, 0);
103 return pvclock_tsc_khz(src);
104}
105
106static void kvm_get_preset_lpj(void)
107{
108 unsigned long khz;
109 u64 lpj;
110
111 khz = kvm_get_tsc_khz();
112
113 lpj = ((u64)khz * 1000);
114 do_div(lpj, HZ);
115 preset_lpj = lpj;
116}
117
118bool kvm_check_and_clear_guest_paused(void)
119{
120 bool ret = false;
121 struct pvclock_vcpu_time_info *src;
122
123 src = &__get_cpu_var(hv_clock);
124 if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
125 __this_cpu_and(hv_clock.flags, ~PVCLOCK_GUEST_STOPPED);
126 ret = true;
127 }
128
129 return ret;
130}
131
132static struct clocksource kvm_clock = {
133 .name = "kvm-clock",
134 .read = kvm_clock_get_cycles,
135 .rating = 400,
136 .mask = CLOCKSOURCE_MASK(64),
137 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
138};
139
140int kvm_register_clock(char *txt)
141{
142 int cpu = smp_processor_id();
143 int low, high, ret;
144
145 low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1;
146 high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32);
147 ret = native_write_msr_safe(msr_kvm_system_time, low, high);
148 printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
149 cpu, high, low, txt);
150
151 return ret;
152}
153
154static void kvm_save_sched_clock_state(void)
155{
156}
157
158static void kvm_restore_sched_clock_state(void)
159{
160 kvm_register_clock("primary cpu clock, resume");
161}
162
163#ifdef CONFIG_X86_LOCAL_APIC
164static void __cpuinit kvm_setup_secondary_clock(void)
165{
166 /*
167 * Now that the first cpu already had this clocksource initialized,
168 * we shouldn't fail.
169 */
170 WARN_ON(kvm_register_clock("secondary cpu clock"));
171}
172#endif
173
174/*
175 * After the clock is registered, the host will keep writing to the
176 * registered memory location. If the guest happens to shutdown, this memory
177 * won't be valid. In cases like kexec, in which you install a new kernel, this
178 * means a random memory location will be kept being written. So before any
179 * kind of shutdown from our side, we unregister the clock by writting anything
180 * that does not have the 'enable' bit set in the msr
181 */
182#ifdef CONFIG_KEXEC
183static void kvm_crash_shutdown(struct pt_regs *regs)
184{
185 native_write_msr(msr_kvm_system_time, 0, 0);
186 kvm_disable_steal_time();
187 native_machine_crash_shutdown(regs);
188}
189#endif
190
191static void kvm_shutdown(void)
192{
193 native_write_msr(msr_kvm_system_time, 0, 0);
194 kvm_disable_steal_time();
195 native_machine_shutdown();
196}
197
198void __init kvmclock_init(void)
199{
200 if (!kvm_para_available())
201 return;
202
203 if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
204 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
205 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
206 } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
207 return;
208
209 printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
210 msr_kvm_system_time, msr_kvm_wall_clock);
211
212 if (kvm_register_clock("boot clock"))
213 return;
214 pv_time_ops.sched_clock = kvm_clock_read;
215 x86_platform.calibrate_tsc = kvm_get_tsc_khz;
216 x86_platform.get_wallclock = kvm_get_wallclock;
217 x86_platform.set_wallclock = kvm_set_wallclock;
218#ifdef CONFIG_X86_LOCAL_APIC
219 x86_cpuinit.early_percpu_clock_init =
220 kvm_setup_secondary_clock;
221#endif
222 x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
223 x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
224 machine_ops.shutdown = kvm_shutdown;
225#ifdef CONFIG_KEXEC
226 machine_ops.crash_shutdown = kvm_crash_shutdown;
227#endif
228 kvm_get_preset_lpj();
229 clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
230 pv_info.paravirt_enabled = 1;
231 pv_info.name = "KVM";
232
233 if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
234 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
235}
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
28#include <asm/x86_init.h>
29#include <asm/reboot.h>
30
31static int kvmclock = 1;
32static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
33static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
34
35static int parse_no_kvmclock(char *arg)
36{
37 kvmclock = 0;
38 return 0;
39}
40early_param("no-kvmclock", parse_no_kvmclock);
41
42/* The hypervisor will put information about time periodically here */
43static struct pvclock_vsyscall_time_info *hv_clock;
44static struct pvclock_wall_clock wall_clock;
45
46/*
47 * The wallclock is the time of day when we booted. Since then, some time may
48 * have elapsed since the hypervisor wrote the data. So we try to account for
49 * that with system time
50 */
51static void kvm_get_wallclock(struct timespec *now)
52{
53 struct pvclock_vcpu_time_info *vcpu_time;
54 int low, high;
55 int cpu;
56
57 low = (int)__pa_symbol(&wall_clock);
58 high = ((u64)__pa_symbol(&wall_clock) >> 32);
59
60 native_write_msr(msr_kvm_wall_clock, low, high);
61
62 preempt_disable();
63 cpu = smp_processor_id();
64
65 vcpu_time = &hv_clock[cpu].pvti;
66 pvclock_read_wallclock(&wall_clock, vcpu_time, now);
67
68 preempt_enable();
69}
70
71static int kvm_set_wallclock(const struct timespec *now)
72{
73 return -1;
74}
75
76static cycle_t kvm_clock_read(void)
77{
78 struct pvclock_vcpu_time_info *src;
79 cycle_t ret;
80 int cpu;
81
82 preempt_disable_notrace();
83 cpu = smp_processor_id();
84 src = &hv_clock[cpu].pvti;
85 ret = pvclock_clocksource_read(src);
86 preempt_enable_notrace();
87 return ret;
88}
89
90static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
91{
92 return kvm_clock_read();
93}
94
95/*
96 * If we don't do that, there is the possibility that the guest
97 * will calibrate under heavy load - thus, getting a lower lpj -
98 * and execute the delays themselves without load. This is wrong,
99 * because no delay loop can finish beforehand.
100 * Any heuristics is subject to fail, because ultimately, a large
101 * poll of guests can be running and trouble each other. So we preset
102 * lpj here
103 */
104static unsigned long kvm_get_tsc_khz(void)
105{
106 struct pvclock_vcpu_time_info *src;
107 int cpu;
108 unsigned long tsc_khz;
109
110 preempt_disable();
111 cpu = smp_processor_id();
112 src = &hv_clock[cpu].pvti;
113 tsc_khz = pvclock_tsc_khz(src);
114 preempt_enable();
115 return tsc_khz;
116}
117
118static void kvm_get_preset_lpj(void)
119{
120 unsigned long khz;
121 u64 lpj;
122
123 khz = kvm_get_tsc_khz();
124
125 lpj = ((u64)khz * 1000);
126 do_div(lpj, HZ);
127 preset_lpj = lpj;
128}
129
130bool kvm_check_and_clear_guest_paused(void)
131{
132 bool ret = false;
133 struct pvclock_vcpu_time_info *src;
134 int cpu = smp_processor_id();
135
136 if (!hv_clock)
137 return ret;
138
139 src = &hv_clock[cpu].pvti;
140 if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
141 src->flags &= ~PVCLOCK_GUEST_STOPPED;
142 pvclock_touch_watchdogs();
143 ret = true;
144 }
145
146 return ret;
147}
148
149static struct clocksource kvm_clock = {
150 .name = "kvm-clock",
151 .read = kvm_clock_get_cycles,
152 .rating = 400,
153 .mask = CLOCKSOURCE_MASK(64),
154 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
155};
156
157int kvm_register_clock(char *txt)
158{
159 int cpu = smp_processor_id();
160 int low, high, ret;
161 struct pvclock_vcpu_time_info *src;
162
163 if (!hv_clock)
164 return 0;
165
166 src = &hv_clock[cpu].pvti;
167 low = (int)slow_virt_to_phys(src) | 1;
168 high = ((u64)slow_virt_to_phys(src) >> 32);
169 ret = native_write_msr_safe(msr_kvm_system_time, low, high);
170 printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
171 cpu, high, low, txt);
172
173 return ret;
174}
175
176static void kvm_save_sched_clock_state(void)
177{
178}
179
180static void kvm_restore_sched_clock_state(void)
181{
182 kvm_register_clock("primary cpu clock, resume");
183}
184
185#ifdef CONFIG_X86_LOCAL_APIC
186static void kvm_setup_secondary_clock(void)
187{
188 /*
189 * Now that the first cpu already had this clocksource initialized,
190 * we shouldn't fail.
191 */
192 WARN_ON(kvm_register_clock("secondary cpu clock"));
193}
194#endif
195
196/*
197 * After the clock is registered, the host will keep writing to the
198 * registered memory location. If the guest happens to shutdown, this memory
199 * won't be valid. In cases like kexec, in which you install a new kernel, this
200 * means a random memory location will be kept being written. So before any
201 * kind of shutdown from our side, we unregister the clock by writting anything
202 * that does not have the 'enable' bit set in the msr
203 */
204#ifdef CONFIG_KEXEC
205static void kvm_crash_shutdown(struct pt_regs *regs)
206{
207 native_write_msr(msr_kvm_system_time, 0, 0);
208 kvm_disable_steal_time();
209 native_machine_crash_shutdown(regs);
210}
211#endif
212
213static void kvm_shutdown(void)
214{
215 native_write_msr(msr_kvm_system_time, 0, 0);
216 kvm_disable_steal_time();
217 native_machine_shutdown();
218}
219
220void __init kvmclock_init(void)
221{
222 unsigned long mem;
223 int size;
224
225 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
226
227 if (!kvm_para_available())
228 return;
229
230 if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
231 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
232 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
233 } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
234 return;
235
236 printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
237 msr_kvm_system_time, msr_kvm_wall_clock);
238
239 mem = memblock_alloc(size, PAGE_SIZE);
240 if (!mem)
241 return;
242 hv_clock = __va(mem);
243 memset(hv_clock, 0, size);
244
245 if (kvm_register_clock("primary cpu clock")) {
246 hv_clock = NULL;
247 memblock_free(mem, size);
248 return;
249 }
250 pv_time_ops.sched_clock = kvm_clock_read;
251 x86_platform.calibrate_tsc = kvm_get_tsc_khz;
252 x86_platform.get_wallclock = kvm_get_wallclock;
253 x86_platform.set_wallclock = kvm_set_wallclock;
254#ifdef CONFIG_X86_LOCAL_APIC
255 x86_cpuinit.early_percpu_clock_init =
256 kvm_setup_secondary_clock;
257#endif
258 x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
259 x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
260 machine_ops.shutdown = kvm_shutdown;
261#ifdef CONFIG_KEXEC
262 machine_ops.crash_shutdown = kvm_crash_shutdown;
263#endif
264 kvm_get_preset_lpj();
265 clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
266 pv_info.paravirt_enabled = 1;
267 pv_info.name = "KVM";
268
269 if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
270 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
271}
272
273int __init kvm_setup_vsyscall_timeinfo(void)
274{
275#ifdef CONFIG_X86_64
276 int cpu;
277 int ret;
278 u8 flags;
279 struct pvclock_vcpu_time_info *vcpu_time;
280 unsigned int size;
281
282 if (!hv_clock)
283 return 0;
284
285 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
286
287 preempt_disable();
288 cpu = smp_processor_id();
289
290 vcpu_time = &hv_clock[cpu].pvti;
291 flags = pvclock_read_flags(vcpu_time);
292
293 if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
294 preempt_enable();
295 return 1;
296 }
297
298 if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
299 preempt_enable();
300 return ret;
301 }
302
303 preempt_enable();
304
305 kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
306#endif
307 return 0;
308}