Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / arch / x86 / kernel / kvmclock.c
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/arch_hooks.h>
23 #include <asm/msr.h>
24 #include <asm/apic.h>
25 #include <linux/percpu.h>
26 #include <asm/reboot.h>
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 */
40 static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock);
41 static struct pvclock_wall_clock wall_clock;
42
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  */
48 static unsigned long kvm_get_wallclock(void)
49 {
50         struct pvclock_vcpu_time_info *vcpu_time;
51         struct timespec ts;
52         int low, high;
53
54         low = (int)__pa(&wall_clock);
55         high = ((u64)__pa(&wall_clock) >> 32);
56         native_write_msr(MSR_KVM_WALL_CLOCK, low, high);
57
58         vcpu_time = &get_cpu_var(hv_clock);
59         pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
60         put_cpu_var(hv_clock);
61
62         return ts.tv_sec;
63 }
64
65 static int kvm_set_wallclock(unsigned long now)
66 {
67         return -1;
68 }
69
70 static cycle_t kvm_clock_read(void)
71 {
72         struct pvclock_vcpu_time_info *src;
73         cycle_t ret;
74
75         src = &get_cpu_var(hv_clock);
76         ret = pvclock_clocksource_read(src);
77         put_cpu_var(hv_clock);
78         return ret;
79 }
80
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
91 static int kvm_register_clock(char *txt)
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);
97         printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
98                cpu, high, low, txt);
99         return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high);
100 }
101
102 #ifdef CONFIG_X86_LOCAL_APIC
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          */
109         WARN_ON(kvm_register_clock("secondary cpu clock"));
110         /* ok, done with our trickery, call native */
111         setup_secondary_APIC_clock();
112 }
113 #endif
114
115 #ifdef CONFIG_SMP
116 static 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
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
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)) {
151                 if (kvm_register_clock("boot clock"))
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;
156 #ifdef CONFIG_X86_LOCAL_APIC
157                 pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock;
158 #endif
159 #ifdef CONFIG_SMP
160                 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
161 #endif
162                 machine_ops.shutdown  = kvm_shutdown;
163 #ifdef CONFIG_KEXEC
164                 machine_ops.crash_shutdown  = kvm_crash_shutdown;
165 #endif
166                 clocksource_register(&kvm_clock);
167         }
168 }