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 | 28 | |
790c73f6 | 29 | static int kvmclock = 1; |
838815a7 GC |
30 | static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; |
31 | static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; | |
790c73f6 GOC |
32 | |
33 | static int parse_no_kvmclock(char *arg) | |
34 | { | |
35 | kvmclock = 0; | |
36 | return 0; | |
37 | } | |
38 | early_param("no-kvmclock", parse_no_kvmclock); | |
39 | ||
40 | /* The hypervisor will put information about time periodically here */ | |
f6e16d5a GH |
41 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock); |
42 | static struct pvclock_wall_clock wall_clock; | |
790c73f6 | 43 | |
790c73f6 GOC |
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 | */ | |
2ddfd20e | 49 | static unsigned long kvm_get_wallclock(void) |
790c73f6 | 50 | { |
f6e16d5a | 51 | struct pvclock_vcpu_time_info *vcpu_time; |
790c73f6 | 52 | struct timespec ts; |
790c73f6 GOC |
53 | int low, high; |
54 | ||
a20316d2 GC |
55 | low = (int)__pa_symbol(&wall_clock); |
56 | high = ((u64)__pa_symbol(&wall_clock) >> 32); | |
838815a7 GC |
57 | |
58 | native_write_msr(msr_kvm_wall_clock, low, high); | |
790c73f6 | 59 | |
f6e16d5a GH |
60 | vcpu_time = &get_cpu_var(hv_clock); |
61 | pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); | |
62 | put_cpu_var(hv_clock); | |
790c73f6 | 63 | |
f6e16d5a | 64 | return ts.tv_sec; |
790c73f6 GOC |
65 | } |
66 | ||
2ddfd20e | 67 | static int kvm_set_wallclock(unsigned long now) |
790c73f6 | 68 | { |
f6e16d5a | 69 | return -1; |
790c73f6 GOC |
70 | } |
71 | ||
790c73f6 GOC |
72 | static cycle_t kvm_clock_read(void) |
73 | { | |
f6e16d5a GH |
74 | struct pvclock_vcpu_time_info *src; |
75 | cycle_t ret; | |
790c73f6 | 76 | |
f6e16d5a GH |
77 | src = &get_cpu_var(hv_clock); |
78 | ret = pvclock_clocksource_read(src); | |
79 | put_cpu_var(hv_clock); | |
80 | return ret; | |
790c73f6 | 81 | } |
f6e16d5a | 82 | |
8e19608e MD |
83 | static cycle_t kvm_clock_get_cycles(struct clocksource *cs) |
84 | { | |
85 | return kvm_clock_read(); | |
86 | } | |
87 | ||
0293615f GC |
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 | */ | |
97 | static unsigned long kvm_get_tsc_khz(void) | |
98 | { | |
e93353c9 EH |
99 | struct pvclock_vcpu_time_info *src; |
100 | src = &per_cpu(hv_clock, 0); | |
101 | return pvclock_tsc_khz(src); | |
0293615f GC |
102 | } |
103 | ||
104 | static void kvm_get_preset_lpj(void) | |
105 | { | |
0293615f GC |
106 | unsigned long khz; |
107 | u64 lpj; | |
108 | ||
e93353c9 | 109 | khz = kvm_get_tsc_khz(); |
0293615f GC |
110 | |
111 | lpj = ((u64)khz * 1000); | |
112 | do_div(lpj, HZ); | |
113 | preset_lpj = lpj; | |
114 | } | |
115 | ||
790c73f6 GOC |
116 | static struct clocksource kvm_clock = { |
117 | .name = "kvm-clock", | |
8e19608e | 118 | .read = kvm_clock_get_cycles, |
790c73f6 GOC |
119 | .rating = 400, |
120 | .mask = CLOCKSOURCE_MASK(64), | |
790c73f6 GOC |
121 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
122 | }; | |
123 | ||
ca3f1017 | 124 | int kvm_register_clock(char *txt) |
790c73f6 GOC |
125 | { |
126 | int cpu = smp_processor_id(); | |
19b6a85b AK |
127 | int low, high, ret; |
128 | ||
790c73f6 GOC |
129 | low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; |
130 | high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); | |
19b6a85b | 131 | ret = native_write_msr_safe(msr_kvm_system_time, low, high); |
f6e16d5a GH |
132 | printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", |
133 | cpu, high, low, txt); | |
838815a7 | 134 | |
19b6a85b | 135 | return ret; |
790c73f6 GOC |
136 | } |
137 | ||
b8ba5f10 | 138 | #ifdef CONFIG_X86_LOCAL_APIC |
23a14b9e | 139 | static void __cpuinit kvm_setup_secondary_clock(void) |
790c73f6 GOC |
140 | { |
141 | /* | |
142 | * Now that the first cpu already had this clocksource initialized, | |
143 | * we shouldn't fail. | |
144 | */ | |
f6e16d5a | 145 | WARN_ON(kvm_register_clock("secondary cpu clock")); |
790c73f6 GOC |
146 | /* ok, done with our trickery, call native */ |
147 | setup_secondary_APIC_clock(); | |
148 | } | |
b8ba5f10 | 149 | #endif |
790c73f6 | 150 | |
1e977aa1 GC |
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 | |
160 | static void kvm_crash_shutdown(struct pt_regs *regs) | |
161 | { | |
838815a7 | 162 | native_write_msr(msr_kvm_system_time, 0, 0); |
1e977aa1 GC |
163 | native_machine_crash_shutdown(regs); |
164 | } | |
165 | #endif | |
166 | ||
167 | static void kvm_shutdown(void) | |
168 | { | |
838815a7 | 169 | native_write_msr(msr_kvm_system_time, 0, 0); |
1e977aa1 GC |
170 | native_machine_shutdown(); |
171 | } | |
172 | ||
790c73f6 GOC |
173 | void __init kvmclock_init(void) |
174 | { | |
175 | if (!kvm_para_available()) | |
176 | return; | |
177 | ||
838815a7 GC |
178 | if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { |
179 | msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; | |
180 | msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; | |
181 | } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE))) | |
182 | return; | |
183 | ||
184 | printk(KERN_INFO "kvm-clock: Using msrs %x and %x", | |
185 | msr_kvm_system_time, msr_kvm_wall_clock); | |
186 | ||
187 | if (kvm_register_clock("boot clock")) | |
188 | return; | |
189 | pv_time_ops.sched_clock = kvm_clock_read; | |
190 | x86_platform.calibrate_tsc = kvm_get_tsc_khz; | |
191 | x86_platform.get_wallclock = kvm_get_wallclock; | |
192 | x86_platform.set_wallclock = kvm_set_wallclock; | |
b8ba5f10 | 193 | #ifdef CONFIG_X86_LOCAL_APIC |
838815a7 GC |
194 | x86_cpuinit.setup_percpu_clockev = |
195 | kvm_setup_secondary_clock; | |
b8ba5f10 | 196 | #endif |
838815a7 | 197 | machine_ops.shutdown = kvm_shutdown; |
1e977aa1 | 198 | #ifdef CONFIG_KEXEC |
838815a7 | 199 | machine_ops.crash_shutdown = kvm_crash_shutdown; |
1e977aa1 | 200 | #endif |
838815a7 | 201 | kvm_get_preset_lpj(); |
b01cc1b0 | 202 | clocksource_register_hz(&kvm_clock, NSEC_PER_SEC); |
838815a7 GC |
203 | pv_info.paravirt_enabled = 1; |
204 | pv_info.name = "KVM"; | |
3a0d7256 GC |
205 | |
206 | if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) | |
207 | pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); | |
790c73f6 | 208 | } |