GNU Linux-libre 4.14.266-gnu1
[releases.git] / arch / x86 / kernel / kvmclock.c
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 #include <linux/sched/clock.h>
29
30 #include <asm/x86_init.h>
31 #include <asm/reboot.h>
32 #include <asm/kvmclock.h>
33
34 static int kvmclock __ro_after_init = 1;
35 static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
36 static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
37 static u64 kvm_sched_clock_offset;
38
39 static int parse_no_kvmclock(char *arg)
40 {
41         kvmclock = 0;
42         return 0;
43 }
44 early_param("no-kvmclock", parse_no_kvmclock);
45
46 /* The hypervisor will put information about time periodically here */
47 static struct pvclock_vsyscall_time_info *hv_clock;
48 static struct pvclock_wall_clock wall_clock;
49
50 /*
51  * The wallclock is the time of day when we booted. Since then, some time may
52  * have elapsed since the hypervisor wrote the data. So we try to account for
53  * that with system time
54  */
55 static void kvm_get_wallclock(struct timespec *now)
56 {
57         struct pvclock_vcpu_time_info *vcpu_time;
58         int low, high;
59         int cpu;
60
61         low = (int)__pa_symbol(&wall_clock);
62         high = ((u64)__pa_symbol(&wall_clock) >> 32);
63
64         native_write_msr(msr_kvm_wall_clock, low, high);
65
66         cpu = get_cpu();
67
68         vcpu_time = &hv_clock[cpu].pvti;
69         pvclock_read_wallclock(&wall_clock, vcpu_time, now);
70
71         put_cpu();
72 }
73
74 static int kvm_set_wallclock(const struct timespec *now)
75 {
76         return -ENODEV;
77 }
78
79 static u64 kvm_clock_read(void)
80 {
81         struct pvclock_vcpu_time_info *src;
82         u64 ret;
83         int cpu;
84
85         preempt_disable_notrace();
86         cpu = smp_processor_id();
87         src = &hv_clock[cpu].pvti;
88         ret = pvclock_clocksource_read(src);
89         preempt_enable_notrace();
90         return ret;
91 }
92
93 static u64 kvm_clock_get_cycles(struct clocksource *cs)
94 {
95         return kvm_clock_read();
96 }
97
98 static u64 kvm_sched_clock_read(void)
99 {
100         return kvm_clock_read() - kvm_sched_clock_offset;
101 }
102
103 static inline void kvm_sched_clock_init(bool stable)
104 {
105         if (!stable) {
106                 pv_time_ops.sched_clock = kvm_clock_read;
107                 clear_sched_clock_stable();
108                 return;
109         }
110
111         kvm_sched_clock_offset = kvm_clock_read();
112         pv_time_ops.sched_clock = kvm_sched_clock_read;
113
114         printk(KERN_INFO "kvm-clock: using sched offset of %llu cycles\n",
115                         kvm_sched_clock_offset);
116
117         BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) >
118                  sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time));
119 }
120
121 /*
122  * If we don't do that, there is the possibility that the guest
123  * will calibrate under heavy load - thus, getting a lower lpj -
124  * and execute the delays themselves without load. This is wrong,
125  * because no delay loop can finish beforehand.
126  * Any heuristics is subject to fail, because ultimately, a large
127  * poll of guests can be running and trouble each other. So we preset
128  * lpj here
129  */
130 static unsigned long kvm_get_tsc_khz(void)
131 {
132         struct pvclock_vcpu_time_info *src;
133         int cpu;
134         unsigned long tsc_khz;
135
136         cpu = get_cpu();
137         src = &hv_clock[cpu].pvti;
138         tsc_khz = pvclock_tsc_khz(src);
139         put_cpu();
140         setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
141         return tsc_khz;
142 }
143
144 static void kvm_get_preset_lpj(void)
145 {
146         unsigned long khz;
147         u64 lpj;
148
149         khz = kvm_get_tsc_khz();
150
151         lpj = ((u64)khz * 1000);
152         do_div(lpj, HZ);
153         preset_lpj = lpj;
154 }
155
156 bool kvm_check_and_clear_guest_paused(void)
157 {
158         bool ret = false;
159         struct pvclock_vcpu_time_info *src;
160         int cpu = smp_processor_id();
161
162         if (!hv_clock)
163                 return ret;
164
165         src = &hv_clock[cpu].pvti;
166         if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
167                 src->flags &= ~PVCLOCK_GUEST_STOPPED;
168                 pvclock_touch_watchdogs();
169                 ret = true;
170         }
171
172         return ret;
173 }
174
175 struct clocksource kvm_clock = {
176         .name = "kvm-clock",
177         .read = kvm_clock_get_cycles,
178         .rating = 400,
179         .mask = CLOCKSOURCE_MASK(64),
180         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
181 };
182 EXPORT_SYMBOL_GPL(kvm_clock);
183
184 int kvm_register_clock(char *txt)
185 {
186         int cpu = smp_processor_id();
187         int low, high, ret;
188         struct pvclock_vcpu_time_info *src;
189
190         if (!hv_clock)
191                 return 0;
192
193         src = &hv_clock[cpu].pvti;
194         low = (int)slow_virt_to_phys(src) | 1;
195         high = ((u64)slow_virt_to_phys(src) >> 32);
196         ret = native_write_msr_safe(msr_kvm_system_time, low, high);
197         printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
198                cpu, high, low, txt);
199
200         return ret;
201 }
202
203 static void kvm_save_sched_clock_state(void)
204 {
205 }
206
207 static void kvm_restore_sched_clock_state(void)
208 {
209         kvm_register_clock("primary cpu clock, resume");
210 }
211
212 #ifdef CONFIG_X86_LOCAL_APIC
213 static void kvm_setup_secondary_clock(void)
214 {
215         /*
216          * Now that the first cpu already had this clocksource initialized,
217          * we shouldn't fail.
218          */
219         WARN_ON(kvm_register_clock("secondary cpu clock"));
220 }
221 #endif
222
223 /*
224  * After the clock is registered, the host will keep writing to the
225  * registered memory location. If the guest happens to shutdown, this memory
226  * won't be valid. In cases like kexec, in which you install a new kernel, this
227  * means a random memory location will be kept being written. So before any
228  * kind of shutdown from our side, we unregister the clock by writing anything
229  * that does not have the 'enable' bit set in the msr
230  */
231 #ifdef CONFIG_KEXEC_CORE
232 static void kvm_crash_shutdown(struct pt_regs *regs)
233 {
234         native_write_msr(msr_kvm_system_time, 0, 0);
235         kvm_disable_steal_time();
236         native_machine_crash_shutdown(regs);
237 }
238 #endif
239
240 static void kvm_shutdown(void)
241 {
242         native_write_msr(msr_kvm_system_time, 0, 0);
243         kvm_disable_steal_time();
244         native_machine_shutdown();
245 }
246
247 void __init kvmclock_init(void)
248 {
249         struct pvclock_vcpu_time_info *vcpu_time;
250         unsigned long mem;
251         int size, cpu;
252         u8 flags;
253
254         size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
255
256         if (!kvm_para_available())
257                 return;
258
259         if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
260                 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
261                 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
262         } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
263                 return;
264
265         printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
266                 msr_kvm_system_time, msr_kvm_wall_clock);
267
268         mem = memblock_alloc(size, PAGE_SIZE);
269         if (!mem)
270                 return;
271         hv_clock = __va(mem);
272         memset(hv_clock, 0, size);
273
274         if (kvm_register_clock("primary cpu clock")) {
275                 hv_clock = NULL;
276                 memblock_free(mem, size);
277                 return;
278         }
279
280         if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
281                 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
282
283         cpu = get_cpu();
284         vcpu_time = &hv_clock[cpu].pvti;
285         flags = pvclock_read_flags(vcpu_time);
286
287         kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT);
288         put_cpu();
289
290         x86_platform.calibrate_tsc = kvm_get_tsc_khz;
291         x86_platform.calibrate_cpu = 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
309 int __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         pvclock_set_pvti_cpu0_va(hv_clock);
333         put_cpu();
334
335         kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
336 #endif
337         return 0;
338 }