Loading...
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
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}