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> | |
1e977aa1 | 25 | #include <asm/reboot.h> |
790c73f6 GOC |
26 | |
27 | #define KVM_SCALE 22 | |
28 | ||
29 | static int kvmclock = 1; | |
30 | ||
31 | static int parse_no_kvmclock(char *arg) | |
32 | { | |
33 | kvmclock = 0; | |
34 | return 0; | |
35 | } | |
36 | early_param("no-kvmclock", parse_no_kvmclock); | |
37 | ||
38 | /* The hypervisor will put information about time periodically here */ | |
f6e16d5a GH |
39 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock); |
40 | static struct pvclock_wall_clock wall_clock; | |
790c73f6 | 41 | |
790c73f6 GOC |
42 | /* |
43 | * The wallclock is the time of day when we booted. Since then, some time may | |
44 | * have elapsed since the hypervisor wrote the data. So we try to account for | |
45 | * that with system time | |
46 | */ | |
2ddfd20e | 47 | static unsigned long kvm_get_wallclock(void) |
790c73f6 | 48 | { |
f6e16d5a | 49 | struct pvclock_vcpu_time_info *vcpu_time; |
790c73f6 | 50 | struct timespec ts; |
790c73f6 GOC |
51 | int low, high; |
52 | ||
53 | low = (int)__pa(&wall_clock); | |
54 | high = ((u64)__pa(&wall_clock) >> 32); | |
f6e16d5a | 55 | native_write_msr(MSR_KVM_WALL_CLOCK, low, high); |
790c73f6 | 56 | |
f6e16d5a GH |
57 | vcpu_time = &get_cpu_var(hv_clock); |
58 | pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); | |
59 | put_cpu_var(hv_clock); | |
790c73f6 | 60 | |
f6e16d5a | 61 | return ts.tv_sec; |
790c73f6 GOC |
62 | } |
63 | ||
2ddfd20e | 64 | static int kvm_set_wallclock(unsigned long now) |
790c73f6 | 65 | { |
f6e16d5a | 66 | return -1; |
790c73f6 GOC |
67 | } |
68 | ||
790c73f6 GOC |
69 | static cycle_t kvm_clock_read(void) |
70 | { | |
f6e16d5a GH |
71 | struct pvclock_vcpu_time_info *src; |
72 | cycle_t ret; | |
790c73f6 | 73 | |
f6e16d5a GH |
74 | src = &get_cpu_var(hv_clock); |
75 | ret = pvclock_clocksource_read(src); | |
76 | put_cpu_var(hv_clock); | |
77 | return ret; | |
790c73f6 | 78 | } |
f6e16d5a | 79 | |
8e19608e MD |
80 | static cycle_t kvm_clock_get_cycles(struct clocksource *cs) |
81 | { | |
82 | return kvm_clock_read(); | |
83 | } | |
84 | ||
0293615f GC |
85 | /* |
86 | * If we don't do that, there is the possibility that the guest | |
87 | * will calibrate under heavy load - thus, getting a lower lpj - | |
88 | * and execute the delays themselves without load. This is wrong, | |
89 | * because no delay loop can finish beforehand. | |
90 | * Any heuristics is subject to fail, because ultimately, a large | |
91 | * poll of guests can be running and trouble each other. So we preset | |
92 | * lpj here | |
93 | */ | |
94 | static unsigned long kvm_get_tsc_khz(void) | |
95 | { | |
e93353c9 EH |
96 | struct pvclock_vcpu_time_info *src; |
97 | src = &per_cpu(hv_clock, 0); | |
98 | return pvclock_tsc_khz(src); | |
0293615f GC |
99 | } |
100 | ||
101 | static void kvm_get_preset_lpj(void) | |
102 | { | |
0293615f GC |
103 | unsigned long khz; |
104 | u64 lpj; | |
105 | ||
e93353c9 | 106 | khz = kvm_get_tsc_khz(); |
0293615f GC |
107 | |
108 | lpj = ((u64)khz * 1000); | |
109 | do_div(lpj, HZ); | |
110 | preset_lpj = lpj; | |
111 | } | |
112 | ||
790c73f6 GOC |
113 | static struct clocksource kvm_clock = { |
114 | .name = "kvm-clock", | |
8e19608e | 115 | .read = kvm_clock_get_cycles, |
790c73f6 GOC |
116 | .rating = 400, |
117 | .mask = CLOCKSOURCE_MASK(64), | |
118 | .mult = 1 << KVM_SCALE, | |
119 | .shift = KVM_SCALE, | |
120 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
121 | }; | |
122 | ||
f6e16d5a | 123 | static int kvm_register_clock(char *txt) |
790c73f6 GOC |
124 | { |
125 | int cpu = smp_processor_id(); | |
126 | int low, high; | |
127 | low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; | |
128 | high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); | |
f6e16d5a GH |
129 | printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", |
130 | cpu, high, low, txt); | |
790c73f6 GOC |
131 | return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high); |
132 | } | |
133 | ||
b8ba5f10 | 134 | #ifdef CONFIG_X86_LOCAL_APIC |
23a14b9e | 135 | static void __cpuinit kvm_setup_secondary_clock(void) |
790c73f6 GOC |
136 | { |
137 | /* | |
138 | * Now that the first cpu already had this clocksource initialized, | |
139 | * we shouldn't fail. | |
140 | */ | |
f6e16d5a | 141 | WARN_ON(kvm_register_clock("secondary cpu clock")); |
790c73f6 GOC |
142 | /* ok, done with our trickery, call native */ |
143 | setup_secondary_APIC_clock(); | |
144 | } | |
b8ba5f10 | 145 | #endif |
790c73f6 | 146 | |
f6e16d5a | 147 | #ifdef CONFIG_SMP |
7e37c299 | 148 | static void __init kvm_smp_prepare_boot_cpu(void) |
f6e16d5a GH |
149 | { |
150 | WARN_ON(kvm_register_clock("primary cpu clock")); | |
151 | native_smp_prepare_boot_cpu(); | |
152 | } | |
153 | #endif | |
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 | { | |
166 | native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); | |
167 | native_machine_crash_shutdown(regs); | |
168 | } | |
169 | #endif | |
170 | ||
171 | static void kvm_shutdown(void) | |
172 | { | |
173 | native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); | |
174 | native_machine_shutdown(); | |
175 | } | |
176 | ||
790c73f6 GOC |
177 | void __init kvmclock_init(void) |
178 | { | |
179 | if (!kvm_para_available()) | |
180 | return; | |
181 | ||
182 | if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { | |
f6e16d5a | 183 | if (kvm_register_clock("boot clock")) |
790c73f6 GOC |
184 | return; |
185 | pv_time_ops.get_wallclock = kvm_get_wallclock; | |
186 | pv_time_ops.set_wallclock = kvm_set_wallclock; | |
187 | pv_time_ops.sched_clock = kvm_clock_read; | |
0293615f | 188 | pv_time_ops.get_tsc_khz = kvm_get_tsc_khz; |
b8ba5f10 | 189 | #ifdef CONFIG_X86_LOCAL_APIC |
790c73f6 | 190 | pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock; |
f6e16d5a GH |
191 | #endif |
192 | #ifdef CONFIG_SMP | |
193 | smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; | |
b8ba5f10 | 194 | #endif |
1e977aa1 GC |
195 | machine_ops.shutdown = kvm_shutdown; |
196 | #ifdef CONFIG_KEXEC | |
197 | machine_ops.crash_shutdown = kvm_crash_shutdown; | |
198 | #endif | |
0293615f | 199 | kvm_get_preset_lpj(); |
790c73f6 | 200 | clocksource_register(&kvm_clock); |
423cd25a GC |
201 | pv_info.paravirt_enabled = 1; |
202 | pv_info.name = "KVM"; | |
790c73f6 GOC |
203 | } |
204 | } |