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790c73f6
GOC
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>
f6e16d5a 21#include <asm/pvclock.h>
790c73f6
GOC
22#include <asm/msr.h>
23#include <asm/apic.h>
24#include <linux/percpu.h>
3b5d56b9 25#include <linux/hardirq.h>
7069ed67 26#include <linux/memblock.h>
736decac
TG
27
28#include <asm/x86_init.h>
1e977aa1 29#include <asm/reboot.h>
790c73f6 30
790c73f6 31static int kvmclock = 1;
838815a7
GC
32static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
33static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
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GOC
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 */
3dc4f7cf 43static struct pvclock_vsyscall_time_info *hv_clock;
f6e16d5a 44static struct pvclock_wall_clock wall_clock;
790c73f6 45
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GOC
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 */
3565184e 51static void kvm_get_wallclock(struct timespec *now)
790c73f6 52{
f6e16d5a 53 struct pvclock_vcpu_time_info *vcpu_time;
790c73f6 54 int low, high;
7069ed67 55 int cpu;
790c73f6 56
a20316d2
GC
57 low = (int)__pa_symbol(&wall_clock);
58 high = ((u64)__pa_symbol(&wall_clock) >> 32);
838815a7
GC
59
60 native_write_msr(msr_kvm_wall_clock, low, high);
790c73f6 61
c6338ce4 62 cpu = get_cpu();
7069ed67 63
3dc4f7cf 64 vcpu_time = &hv_clock[cpu].pvti;
3565184e 65 pvclock_read_wallclock(&wall_clock, vcpu_time, now);
7069ed67 66
c6338ce4 67 put_cpu();
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GOC
68}
69
3565184e 70static int kvm_set_wallclock(const struct timespec *now)
790c73f6 71{
f6e16d5a 72 return -1;
790c73f6
GOC
73}
74
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GOC
75static cycle_t kvm_clock_read(void)
76{
f6e16d5a
GH
77 struct pvclock_vcpu_time_info *src;
78 cycle_t ret;
7069ed67 79 int cpu;
790c73f6 80
95ef1e52 81 preempt_disable_notrace();
7069ed67 82 cpu = smp_processor_id();
3dc4f7cf 83 src = &hv_clock[cpu].pvti;
f6e16d5a 84 ret = pvclock_clocksource_read(src);
95ef1e52 85 preempt_enable_notrace();
f6e16d5a 86 return ret;
790c73f6 87}
f6e16d5a 88
8e19608e
MD
89static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
90{
91 return kvm_clock_read();
92}
93
0293615f
GC
94/*
95 * If we don't do that, there is the possibility that the guest
96 * will calibrate under heavy load - thus, getting a lower lpj -
97 * and execute the delays themselves without load. This is wrong,
98 * because no delay loop can finish beforehand.
99 * Any heuristics is subject to fail, because ultimately, a large
100 * poll of guests can be running and trouble each other. So we preset
101 * lpj here
102 */
103static unsigned long kvm_get_tsc_khz(void)
104{
e93353c9 105 struct pvclock_vcpu_time_info *src;
7069ed67
MT
106 int cpu;
107 unsigned long tsc_khz;
108
c6338ce4 109 cpu = get_cpu();
3dc4f7cf 110 src = &hv_clock[cpu].pvti;
7069ed67 111 tsc_khz = pvclock_tsc_khz(src);
c6338ce4 112 put_cpu();
7069ed67 113 return tsc_khz;
0293615f
GC
114}
115
116static void kvm_get_preset_lpj(void)
117{
0293615f
GC
118 unsigned long khz;
119 u64 lpj;
120
e93353c9 121 khz = kvm_get_tsc_khz();
0293615f
GC
122
123 lpj = ((u64)khz * 1000);
124 do_div(lpj, HZ);
125 preset_lpj = lpj;
126}
127
3b5d56b9
EM
128bool kvm_check_and_clear_guest_paused(void)
129{
130 bool ret = false;
131 struct pvclock_vcpu_time_info *src;
7069ed67
MT
132 int cpu = smp_processor_id();
133
134 if (!hv_clock)
135 return ret;
3b5d56b9 136
3dc4f7cf 137 src = &hv_clock[cpu].pvti;
3b5d56b9 138 if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
7069ed67 139 src->flags &= ~PVCLOCK_GUEST_STOPPED;
d63285e9 140 pvclock_touch_watchdogs();
3b5d56b9
EM
141 ret = true;
142 }
143
144 return ret;
145}
3b5d56b9 146
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GOC
147static struct clocksource kvm_clock = {
148 .name = "kvm-clock",
8e19608e 149 .read = kvm_clock_get_cycles,
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GOC
150 .rating = 400,
151 .mask = CLOCKSOURCE_MASK(64),
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GOC
152 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
153};
154
ca3f1017 155int kvm_register_clock(char *txt)
790c73f6
GOC
156{
157 int cpu = smp_processor_id();
19b6a85b 158 int low, high, ret;
fe1140cc
JK
159 struct pvclock_vcpu_time_info *src;
160
161 if (!hv_clock)
162 return 0;
19b6a85b 163
fe1140cc 164 src = &hv_clock[cpu].pvti;
5dfd486c
DH
165 low = (int)slow_virt_to_phys(src) | 1;
166 high = ((u64)slow_virt_to_phys(src) >> 32);
19b6a85b 167 ret = native_write_msr_safe(msr_kvm_system_time, low, high);
f6e16d5a
GH
168 printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
169 cpu, high, low, txt);
838815a7 170
19b6a85b 171 return ret;
790c73f6
GOC
172}
173
b74f05d6
MT
174static void kvm_save_sched_clock_state(void)
175{
176}
177
178static void kvm_restore_sched_clock_state(void)
179{
180 kvm_register_clock("primary cpu clock, resume");
181}
182
b8ba5f10 183#ifdef CONFIG_X86_LOCAL_APIC
148f9bb8 184static void kvm_setup_secondary_clock(void)
790c73f6
GOC
185{
186 /*
187 * Now that the first cpu already had this clocksource initialized,
188 * we shouldn't fail.
189 */
f6e16d5a 190 WARN_ON(kvm_register_clock("secondary cpu clock"));
790c73f6 191}
b8ba5f10 192#endif
790c73f6 193
1e977aa1
GC
194/*
195 * After the clock is registered, the host will keep writing to the
196 * registered memory location. If the guest happens to shutdown, this memory
197 * won't be valid. In cases like kexec, in which you install a new kernel, this
198 * means a random memory location will be kept being written. So before any
199 * kind of shutdown from our side, we unregister the clock by writting anything
200 * that does not have the 'enable' bit set in the msr
201 */
202#ifdef CONFIG_KEXEC
203static void kvm_crash_shutdown(struct pt_regs *regs)
204{
838815a7 205 native_write_msr(msr_kvm_system_time, 0, 0);
d910f5c1 206 kvm_disable_steal_time();
1e977aa1
GC
207 native_machine_crash_shutdown(regs);
208}
209#endif
210
211static void kvm_shutdown(void)
212{
838815a7 213 native_write_msr(msr_kvm_system_time, 0, 0);
d910f5c1 214 kvm_disable_steal_time();
1e977aa1
GC
215 native_machine_shutdown();
216}
217
790c73f6
GOC
218void __init kvmclock_init(void)
219{
7069ed67 220 unsigned long mem;
ed55705d
MT
221 int size;
222
223 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
7069ed67 224
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GOC
225 if (!kvm_para_available())
226 return;
227
838815a7
GC
228 if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
229 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
230 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
231 } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
232 return;
233
234 printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
235 msr_kvm_system_time, msr_kvm_wall_clock);
236
ed55705d 237 mem = memblock_alloc(size, PAGE_SIZE);
7069ed67
MT
238 if (!mem)
239 return;
240 hv_clock = __va(mem);
07868fc6 241 memset(hv_clock, 0, size);
7069ed67 242
0d75de4a 243 if (kvm_register_clock("primary cpu clock")) {
7069ed67 244 hv_clock = NULL;
ed55705d 245 memblock_free(mem, size);
838815a7 246 return;
7069ed67 247 }
838815a7
GC
248 pv_time_ops.sched_clock = kvm_clock_read;
249 x86_platform.calibrate_tsc = kvm_get_tsc_khz;
250 x86_platform.get_wallclock = kvm_get_wallclock;
251 x86_platform.set_wallclock = kvm_set_wallclock;
b8ba5f10 252#ifdef CONFIG_X86_LOCAL_APIC
df156f90 253 x86_cpuinit.early_percpu_clock_init =
838815a7 254 kvm_setup_secondary_clock;
b8ba5f10 255#endif
b74f05d6
MT
256 x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
257 x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
838815a7 258 machine_ops.shutdown = kvm_shutdown;
1e977aa1 259#ifdef CONFIG_KEXEC
838815a7 260 machine_ops.crash_shutdown = kvm_crash_shutdown;
1e977aa1 261#endif
838815a7 262 kvm_get_preset_lpj();
b01cc1b0 263 clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
838815a7 264 pv_info.name = "KVM";
3a0d7256
GC
265
266 if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
267 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
790c73f6 268}
3dc4f7cf
MT
269
270int __init kvm_setup_vsyscall_timeinfo(void)
271{
272#ifdef CONFIG_X86_64
273 int cpu;
274 int ret;
275 u8 flags;
276 struct pvclock_vcpu_time_info *vcpu_time;
277 unsigned int size;
278
fe1140cc
JK
279 if (!hv_clock)
280 return 0;
281
ed55705d 282 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
3dc4f7cf 283
c6338ce4 284 cpu = get_cpu();
3dc4f7cf
MT
285
286 vcpu_time = &hv_clock[cpu].pvti;
287 flags = pvclock_read_flags(vcpu_time);
288
289 if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
c6338ce4 290 put_cpu();
3dc4f7cf
MT
291 return 1;
292 }
293
294 if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
c6338ce4 295 put_cpu();
3dc4f7cf
MT
296 return ret;
297 }
298
c6338ce4 299 put_cpu();
3dc4f7cf
MT
300
301 kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
302#endif
303 return 0;
304}