Commit | Line | Data |
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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> | |
736decac TG |
25 | |
26 | #include <asm/x86_init.h> | |
1e977aa1 | 27 | #include <asm/reboot.h> |
790c73f6 GOC |
28 | |
29 | #define KVM_SCALE 22 | |
30 | ||
31 | static int kvmclock = 1; | |
838815a7 GC |
32 | static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; |
33 | static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; | |
790c73f6 GOC |
34 | |
35 | static int parse_no_kvmclock(char *arg) | |
36 | { | |
37 | kvmclock = 0; | |
38 | return 0; | |
39 | } | |
40 | early_param("no-kvmclock", parse_no_kvmclock); | |
41 | ||
42 | /* The hypervisor will put information about time periodically here */ | |
f6e16d5a GH |
43 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock); |
44 | static struct pvclock_wall_clock wall_clock; | |
790c73f6 | 45 | |
790c73f6 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 | */ | |
2ddfd20e | 51 | static unsigned long kvm_get_wallclock(void) |
790c73f6 | 52 | { |
f6e16d5a | 53 | struct pvclock_vcpu_time_info *vcpu_time; |
790c73f6 | 54 | struct timespec ts; |
790c73f6 GOC |
55 | int low, high; |
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 | |
f6e16d5a GH |
62 | vcpu_time = &get_cpu_var(hv_clock); |
63 | pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); | |
64 | put_cpu_var(hv_clock); | |
790c73f6 | 65 | |
f6e16d5a | 66 | return ts.tv_sec; |
790c73f6 GOC |
67 | } |
68 | ||
2ddfd20e | 69 | static int kvm_set_wallclock(unsigned long now) |
790c73f6 | 70 | { |
f6e16d5a | 71 | return -1; |
790c73f6 GOC |
72 | } |
73 | ||
790c73f6 GOC |
74 | static cycle_t kvm_clock_read(void) |
75 | { | |
f6e16d5a GH |
76 | struct pvclock_vcpu_time_info *src; |
77 | cycle_t ret; | |
790c73f6 | 78 | |
f6e16d5a GH |
79 | src = &get_cpu_var(hv_clock); |
80 | ret = pvclock_clocksource_read(src); | |
81 | put_cpu_var(hv_clock); | |
82 | return ret; | |
790c73f6 | 83 | } |
f6e16d5a | 84 | |
8e19608e MD |
85 | static cycle_t kvm_clock_get_cycles(struct clocksource *cs) |
86 | { | |
87 | return kvm_clock_read(); | |
88 | } | |
89 | ||
0293615f GC |
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 | */ | |
99 | static unsigned long kvm_get_tsc_khz(void) | |
100 | { | |
e93353c9 EH |
101 | struct pvclock_vcpu_time_info *src; |
102 | src = &per_cpu(hv_clock, 0); | |
103 | return pvclock_tsc_khz(src); | |
0293615f GC |
104 | } |
105 | ||
106 | static void kvm_get_preset_lpj(void) | |
107 | { | |
0293615f GC |
108 | unsigned long khz; |
109 | u64 lpj; | |
110 | ||
e93353c9 | 111 | khz = kvm_get_tsc_khz(); |
0293615f GC |
112 | |
113 | lpj = ((u64)khz * 1000); | |
114 | do_div(lpj, HZ); | |
115 | preset_lpj = lpj; | |
116 | } | |
117 | ||
790c73f6 GOC |
118 | static struct clocksource kvm_clock = { |
119 | .name = "kvm-clock", | |
8e19608e | 120 | .read = kvm_clock_get_cycles, |
790c73f6 GOC |
121 | .rating = 400, |
122 | .mask = CLOCKSOURCE_MASK(64), | |
123 | .mult = 1 << KVM_SCALE, | |
124 | .shift = KVM_SCALE, | |
125 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
126 | }; | |
127 | ||
ca3f1017 | 128 | int kvm_register_clock(char *txt) |
790c73f6 GOC |
129 | { |
130 | int cpu = smp_processor_id(); | |
19b6a85b AK |
131 | int low, high, ret; |
132 | ||
790c73f6 GOC |
133 | low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; |
134 | high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); | |
19b6a85b | 135 | ret = native_write_msr_safe(msr_kvm_system_time, low, high); |
f6e16d5a GH |
136 | printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", |
137 | cpu, high, low, txt); | |
838815a7 | 138 | |
19b6a85b | 139 | return ret; |
790c73f6 GOC |
140 | } |
141 | ||
b8ba5f10 | 142 | #ifdef CONFIG_X86_LOCAL_APIC |
23a14b9e | 143 | static void __cpuinit kvm_setup_secondary_clock(void) |
790c73f6 GOC |
144 | { |
145 | /* | |
146 | * Now that the first cpu already had this clocksource initialized, | |
147 | * we shouldn't fail. | |
148 | */ | |
f6e16d5a | 149 | WARN_ON(kvm_register_clock("secondary cpu clock")); |
790c73f6 GOC |
150 | /* ok, done with our trickery, call native */ |
151 | setup_secondary_APIC_clock(); | |
152 | } | |
b8ba5f10 | 153 | #endif |
790c73f6 | 154 | |
1e977aa1 GC |
155 | /* |
156 | * After the clock is registered, the host will keep writing to the | |
157 | * registered memory location. If the guest happens to shutdown, this memory | |
158 | * won't be valid. In cases like kexec, in which you install a new kernel, this | |
159 | * means a random memory location will be kept being written. So before any | |
160 | * kind of shutdown from our side, we unregister the clock by writting anything | |
161 | * that does not have the 'enable' bit set in the msr | |
162 | */ | |
163 | #ifdef CONFIG_KEXEC | |
164 | static void kvm_crash_shutdown(struct pt_regs *regs) | |
165 | { | |
838815a7 | 166 | native_write_msr(msr_kvm_system_time, 0, 0); |
1e977aa1 GC |
167 | native_machine_crash_shutdown(regs); |
168 | } | |
169 | #endif | |
170 | ||
171 | static void kvm_shutdown(void) | |
172 | { | |
838815a7 | 173 | native_write_msr(msr_kvm_system_time, 0, 0); |
1e977aa1 GC |
174 | native_machine_shutdown(); |
175 | } | |
176 | ||
790c73f6 GOC |
177 | void __init kvmclock_init(void) |
178 | { | |
179 | if (!kvm_para_available()) | |
180 | return; | |
181 | ||
838815a7 GC |
182 | if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { |
183 | msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; | |
184 | msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; | |
185 | } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE))) | |
186 | return; | |
187 | ||
188 | printk(KERN_INFO "kvm-clock: Using msrs %x and %x", | |
189 | msr_kvm_system_time, msr_kvm_wall_clock); | |
190 | ||
191 | if (kvm_register_clock("boot clock")) | |
192 | return; | |
193 | pv_time_ops.sched_clock = kvm_clock_read; | |
194 | x86_platform.calibrate_tsc = kvm_get_tsc_khz; | |
195 | x86_platform.get_wallclock = kvm_get_wallclock; | |
196 | x86_platform.set_wallclock = kvm_set_wallclock; | |
b8ba5f10 | 197 | #ifdef CONFIG_X86_LOCAL_APIC |
838815a7 GC |
198 | x86_cpuinit.setup_percpu_clockev = |
199 | kvm_setup_secondary_clock; | |
b8ba5f10 | 200 | #endif |
838815a7 | 201 | machine_ops.shutdown = kvm_shutdown; |
1e977aa1 | 202 | #ifdef CONFIG_KEXEC |
838815a7 | 203 | machine_ops.crash_shutdown = kvm_crash_shutdown; |
1e977aa1 | 204 | #endif |
838815a7 GC |
205 | kvm_get_preset_lpj(); |
206 | clocksource_register(&kvm_clock); | |
207 | pv_info.paravirt_enabled = 1; | |
208 | pv_info.name = "KVM"; | |
3a0d7256 GC |
209 | |
210 | if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) | |
211 | pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); | |
790c73f6 | 212 | } |