Merge tag 'kvm-3.9-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
[linux-3.10.git] / 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/msr.h>
23 #include <asm/apic.h>
24 #include <linux/percpu.h>
25 #include <linux/hardirq.h>
26 #include <linux/memblock.h>
27
28 #include <asm/x86_init.h>
29 #include <asm/reboot.h>
30
31 static int kvmclock = 1;
32 static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
33 static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
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 */
43 static struct pvclock_vsyscall_time_info *hv_clock;
44 static struct pvclock_wall_clock wall_clock;
45
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  */
51 static unsigned long kvm_get_wallclock(void)
52 {
53         struct pvclock_vcpu_time_info *vcpu_time;
54         struct timespec ts;
55         int low, high;
56         int cpu;
57
58         low = (int)__pa_symbol(&wall_clock);
59         high = ((u64)__pa_symbol(&wall_clock) >> 32);
60
61         native_write_msr(msr_kvm_wall_clock, low, high);
62
63         preempt_disable();
64         cpu = smp_processor_id();
65
66         vcpu_time = &hv_clock[cpu].pvti;
67         pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
68
69         preempt_enable();
70
71         return ts.tv_sec;
72 }
73
74 static int kvm_set_wallclock(unsigned long now)
75 {
76         return -1;
77 }
78
79 static cycle_t kvm_clock_read(void)
80 {
81         struct pvclock_vcpu_time_info *src;
82         cycle_t ret;
83         int cpu;
84
85         preempt_disable_notrace();
86         cpu = smp_processor_id();
87         src = &hv_clock[cpu].pvti;
88         ret = pvclock_clocksource_read(src);
89         preempt_enable_notrace();
90         return ret;
91 }
92
93 static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
94 {
95         return kvm_clock_read();
96 }
97
98 /*
99  * If we don't do that, there is the possibility that the guest
100  * will calibrate under heavy load - thus, getting a lower lpj -
101  * and execute the delays themselves without load. This is wrong,
102  * because no delay loop can finish beforehand.
103  * Any heuristics is subject to fail, because ultimately, a large
104  * poll of guests can be running and trouble each other. So we preset
105  * lpj here
106  */
107 static unsigned long kvm_get_tsc_khz(void)
108 {
109         struct pvclock_vcpu_time_info *src;
110         int cpu;
111         unsigned long tsc_khz;
112
113         preempt_disable();
114         cpu = smp_processor_id();
115         src = &hv_clock[cpu].pvti;
116         tsc_khz = pvclock_tsc_khz(src);
117         preempt_enable();
118         return tsc_khz;
119 }
120
121 static void kvm_get_preset_lpj(void)
122 {
123         unsigned long khz;
124         u64 lpj;
125
126         khz = kvm_get_tsc_khz();
127
128         lpj = ((u64)khz * 1000);
129         do_div(lpj, HZ);
130         preset_lpj = lpj;
131 }
132
133 bool kvm_check_and_clear_guest_paused(void)
134 {
135         bool ret = false;
136         struct pvclock_vcpu_time_info *src;
137         int cpu = smp_processor_id();
138
139         if (!hv_clock)
140                 return ret;
141
142         src = &hv_clock[cpu].pvti;
143         if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
144                 src->flags &= ~PVCLOCK_GUEST_STOPPED;
145                 ret = true;
146         }
147
148         return ret;
149 }
150
151 static struct clocksource kvm_clock = {
152         .name = "kvm-clock",
153         .read = kvm_clock_get_cycles,
154         .rating = 400,
155         .mask = CLOCKSOURCE_MASK(64),
156         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
157 };
158
159 int kvm_register_clock(char *txt)
160 {
161         int cpu = smp_processor_id();
162         int low, high, ret;
163         struct pvclock_vcpu_time_info *src = &hv_clock[cpu].pvti;
164
165         low = (int)slow_virt_to_phys(src) | 1;
166         high = ((u64)slow_virt_to_phys(src) >> 32);
167         ret = native_write_msr_safe(msr_kvm_system_time, low, high);
168         printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
169                cpu, high, low, txt);
170
171         return ret;
172 }
173
174 static void kvm_save_sched_clock_state(void)
175 {
176 }
177
178 static void kvm_restore_sched_clock_state(void)
179 {
180         kvm_register_clock("primary cpu clock, resume");
181 }
182
183 #ifdef CONFIG_X86_LOCAL_APIC
184 static void __cpuinit kvm_setup_secondary_clock(void)
185 {
186         /*
187          * Now that the first cpu already had this clocksource initialized,
188          * we shouldn't fail.
189          */
190         WARN_ON(kvm_register_clock("secondary cpu clock"));
191 }
192 #endif
193
194 /*
195  * After the clock is registered, the host will keep writing to the
196  * registered memory location. If the guest happens to shutdown, this memory
197  * won't be valid. In cases like kexec, in which you install a new kernel, this
198  * means a random memory location will be kept being written. So before any
199  * kind of shutdown from our side, we unregister the clock by writting anything
200  * that does not have the 'enable' bit set in the msr
201  */
202 #ifdef CONFIG_KEXEC
203 static void kvm_crash_shutdown(struct pt_regs *regs)
204 {
205         native_write_msr(msr_kvm_system_time, 0, 0);
206         kvm_disable_steal_time();
207         native_machine_crash_shutdown(regs);
208 }
209 #endif
210
211 static void kvm_shutdown(void)
212 {
213         native_write_msr(msr_kvm_system_time, 0, 0);
214         kvm_disable_steal_time();
215         native_machine_shutdown();
216 }
217
218 void __init kvmclock_init(void)
219 {
220         unsigned long mem;
221         int size;
222
223         size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
224
225         if (!kvm_para_available())
226                 return;
227
228         if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
229                 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
230                 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
231         } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
232                 return;
233
234         printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
235                 msr_kvm_system_time, msr_kvm_wall_clock);
236
237         mem = memblock_alloc(size, PAGE_SIZE);
238         if (!mem)
239                 return;
240         hv_clock = __va(mem);
241
242         if (kvm_register_clock("boot clock")) {
243                 hv_clock = NULL;
244                 memblock_free(mem, size);
245                 return;
246         }
247         pv_time_ops.sched_clock = kvm_clock_read;
248         x86_platform.calibrate_tsc = kvm_get_tsc_khz;
249         x86_platform.get_wallclock = kvm_get_wallclock;
250         x86_platform.set_wallclock = kvm_set_wallclock;
251 #ifdef CONFIG_X86_LOCAL_APIC
252         x86_cpuinit.early_percpu_clock_init =
253                 kvm_setup_secondary_clock;
254 #endif
255         x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
256         x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
257         machine_ops.shutdown  = kvm_shutdown;
258 #ifdef CONFIG_KEXEC
259         machine_ops.crash_shutdown  = kvm_crash_shutdown;
260 #endif
261         kvm_get_preset_lpj();
262         clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
263         pv_info.paravirt_enabled = 1;
264         pv_info.name = "KVM";
265
266         if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
267                 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
268 }
269
270 int __init kvm_setup_vsyscall_timeinfo(void)
271 {
272 #ifdef CONFIG_X86_64
273         int cpu;
274         int ret;
275         u8 flags;
276         struct pvclock_vcpu_time_info *vcpu_time;
277         unsigned int size;
278
279         size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
280
281         preempt_disable();
282         cpu = smp_processor_id();
283
284         vcpu_time = &hv_clock[cpu].pvti;
285         flags = pvclock_read_flags(vcpu_time);
286
287         if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
288                 preempt_enable();
289                 return 1;
290         }
291
292         if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
293                 preempt_enable();
294                 return ret;
295         }
296
297         preempt_enable();
298
299         kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
300 #endif
301         return 0;
302 }