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/arch_hooks.h> |
23 | #include <asm/msr.h> | |
24 | #include <asm/apic.h> | |
25 | #include <linux/percpu.h> | |
1e977aa1 | 26 | #include <asm/reboot.h> |
790c73f6 GOC |
27 | |
28 | #define KVM_SCALE 22 | |
29 | ||
30 | static int kvmclock = 1; | |
31 | ||
32 | static int parse_no_kvmclock(char *arg) | |
33 | { | |
34 | kvmclock = 0; | |
35 | return 0; | |
36 | } | |
37 | early_param("no-kvmclock", parse_no_kvmclock); | |
38 | ||
39 | /* The hypervisor will put information about time periodically here */ | |
f6e16d5a GH |
40 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock); |
41 | static struct pvclock_wall_clock wall_clock; | |
790c73f6 | 42 | |
790c73f6 GOC |
43 | /* |
44 | * The wallclock is the time of day when we booted. Since then, some time may | |
45 | * have elapsed since the hypervisor wrote the data. So we try to account for | |
46 | * that with system time | |
47 | */ | |
2ddfd20e | 48 | static unsigned long kvm_get_wallclock(void) |
790c73f6 | 49 | { |
f6e16d5a | 50 | struct pvclock_vcpu_time_info *vcpu_time; |
790c73f6 | 51 | struct timespec ts; |
790c73f6 GOC |
52 | int low, high; |
53 | ||
54 | low = (int)__pa(&wall_clock); | |
55 | high = ((u64)__pa(&wall_clock) >> 32); | |
f6e16d5a | 56 | native_write_msr(MSR_KVM_WALL_CLOCK, low, high); |
790c73f6 | 57 | |
f6e16d5a GH |
58 | vcpu_time = &get_cpu_var(hv_clock); |
59 | pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); | |
60 | put_cpu_var(hv_clock); | |
790c73f6 | 61 | |
f6e16d5a | 62 | return ts.tv_sec; |
790c73f6 GOC |
63 | } |
64 | ||
2ddfd20e | 65 | static int kvm_set_wallclock(unsigned long now) |
790c73f6 | 66 | { |
f6e16d5a | 67 | return -1; |
790c73f6 GOC |
68 | } |
69 | ||
790c73f6 GOC |
70 | static cycle_t kvm_clock_read(void) |
71 | { | |
f6e16d5a GH |
72 | struct pvclock_vcpu_time_info *src; |
73 | cycle_t ret; | |
790c73f6 | 74 | |
f6e16d5a GH |
75 | src = &get_cpu_var(hv_clock); |
76 | ret = pvclock_clocksource_read(src); | |
77 | put_cpu_var(hv_clock); | |
78 | return ret; | |
790c73f6 | 79 | } |
f6e16d5a | 80 | |
790c73f6 GOC |
81 | static struct clocksource kvm_clock = { |
82 | .name = "kvm-clock", | |
83 | .read = kvm_clock_read, | |
84 | .rating = 400, | |
85 | .mask = CLOCKSOURCE_MASK(64), | |
86 | .mult = 1 << KVM_SCALE, | |
87 | .shift = KVM_SCALE, | |
88 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
89 | }; | |
90 | ||
f6e16d5a | 91 | static int kvm_register_clock(char *txt) |
790c73f6 GOC |
92 | { |
93 | int cpu = smp_processor_id(); | |
94 | int low, high; | |
95 | low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; | |
96 | high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); | |
f6e16d5a GH |
97 | printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", |
98 | cpu, high, low, txt); | |
790c73f6 GOC |
99 | return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high); |
100 | } | |
101 | ||
b8ba5f10 | 102 | #ifdef CONFIG_X86_LOCAL_APIC |
790c73f6 GOC |
103 | static void kvm_setup_secondary_clock(void) |
104 | { | |
105 | /* | |
106 | * Now that the first cpu already had this clocksource initialized, | |
107 | * we shouldn't fail. | |
108 | */ | |
f6e16d5a | 109 | WARN_ON(kvm_register_clock("secondary cpu clock")); |
790c73f6 GOC |
110 | /* ok, done with our trickery, call native */ |
111 | setup_secondary_APIC_clock(); | |
112 | } | |
b8ba5f10 | 113 | #endif |
790c73f6 | 114 | |
f6e16d5a GH |
115 | #ifdef CONFIG_SMP |
116 | void __init kvm_smp_prepare_boot_cpu(void) | |
117 | { | |
118 | WARN_ON(kvm_register_clock("primary cpu clock")); | |
119 | native_smp_prepare_boot_cpu(); | |
120 | } | |
121 | #endif | |
122 | ||
1e977aa1 GC |
123 | /* |
124 | * After the clock is registered, the host will keep writing to the | |
125 | * registered memory location. If the guest happens to shutdown, this memory | |
126 | * won't be valid. In cases like kexec, in which you install a new kernel, this | |
127 | * means a random memory location will be kept being written. So before any | |
128 | * kind of shutdown from our side, we unregister the clock by writting anything | |
129 | * that does not have the 'enable' bit set in the msr | |
130 | */ | |
131 | #ifdef CONFIG_KEXEC | |
132 | static void kvm_crash_shutdown(struct pt_regs *regs) | |
133 | { | |
134 | native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); | |
135 | native_machine_crash_shutdown(regs); | |
136 | } | |
137 | #endif | |
138 | ||
139 | static void kvm_shutdown(void) | |
140 | { | |
141 | native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); | |
142 | native_machine_shutdown(); | |
143 | } | |
144 | ||
790c73f6 GOC |
145 | void __init kvmclock_init(void) |
146 | { | |
147 | if (!kvm_para_available()) | |
148 | return; | |
149 | ||
150 | if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { | |
f6e16d5a | 151 | if (kvm_register_clock("boot clock")) |
790c73f6 GOC |
152 | return; |
153 | pv_time_ops.get_wallclock = kvm_get_wallclock; | |
154 | pv_time_ops.set_wallclock = kvm_set_wallclock; | |
155 | pv_time_ops.sched_clock = kvm_clock_read; | |
b8ba5f10 | 156 | #ifdef CONFIG_X86_LOCAL_APIC |
790c73f6 | 157 | pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock; |
f6e16d5a GH |
158 | #endif |
159 | #ifdef CONFIG_SMP | |
160 | smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; | |
b8ba5f10 | 161 | #endif |
1e977aa1 GC |
162 | machine_ops.shutdown = kvm_shutdown; |
163 | #ifdef CONFIG_KEXEC | |
164 | machine_ops.crash_shutdown = kvm_crash_shutdown; | |
165 | #endif | |
790c73f6 GOC |
166 | clocksource_register(&kvm_clock); |
167 | } | |
168 | } |