~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/x86/kernel/kvmclock.c

Version: ~ [ linux-5.15-rc5 ] ~ [ linux-5.14.11 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.72 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.152 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.210 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.250 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.286 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.288 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 void kvm_get_wallclock(struct timespec *now)
 52 {
 53         struct pvclock_vcpu_time_info *vcpu_time;
 54         int low, high;
 55         int cpu;
 56 
 57         low = (int)__pa_symbol(&wall_clock);
 58         high = ((u64)__pa_symbol(&wall_clock) >> 32);
 59 
 60         native_write_msr(msr_kvm_wall_clock, low, high);
 61 
 62         preempt_disable();
 63         cpu = smp_processor_id();
 64 
 65         vcpu_time = &hv_clock[cpu].pvti;
 66         pvclock_read_wallclock(&wall_clock, vcpu_time, now);
 67 
 68         preempt_enable();
 69 }
 70 
 71 static int kvm_set_wallclock(const struct timespec *now)
 72 {
 73         return -1;
 74 }
 75 
 76 static cycle_t kvm_clock_read(void)
 77 {
 78         struct pvclock_vcpu_time_info *src;
 79         cycle_t ret;
 80         int cpu;
 81 
 82         preempt_disable_notrace();
 83         cpu = smp_processor_id();
 84         src = &hv_clock[cpu].pvti;
 85         ret = pvclock_clocksource_read(src);
 86         preempt_enable_notrace();
 87         return ret;
 88 }
 89 
 90 static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
 91 {
 92         return kvm_clock_read();
 93 }
 94 
 95 /*
 96  * If we don't do that, there is the possibility that the guest
 97  * will calibrate under heavy load - thus, getting a lower lpj -
 98  * and execute the delays themselves without load. This is wrong,
 99  * because no delay loop can finish beforehand.
100  * Any heuristics is subject to fail, because ultimately, a large
101  * poll of guests can be running and trouble each other. So we preset
102  * lpj here
103  */
104 static unsigned long kvm_get_tsc_khz(void)
105 {
106         struct pvclock_vcpu_time_info *src;
107         int cpu;
108         unsigned long tsc_khz;
109 
110         preempt_disable();
111         cpu = smp_processor_id();
112         src = &hv_clock[cpu].pvti;
113         tsc_khz = pvclock_tsc_khz(src);
114         preempt_enable();
115         return tsc_khz;
116 }
117 
118 static void kvm_get_preset_lpj(void)
119 {
120         unsigned long khz;
121         u64 lpj;
122 
123         khz = kvm_get_tsc_khz();
124 
125         lpj = ((u64)khz * 1000);
126         do_div(lpj, HZ);
127         preset_lpj = lpj;
128 }
129 
130 bool kvm_check_and_clear_guest_paused(void)
131 {
132         bool ret = false;
133         struct pvclock_vcpu_time_info *src;
134         int cpu = smp_processor_id();
135 
136         if (!hv_clock)
137                 return ret;
138 
139         src = &hv_clock[cpu].pvti;
140         if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
141                 src->flags &= ~PVCLOCK_GUEST_STOPPED;
142                 pvclock_touch_watchdogs();
143                 ret = true;
144         }
145 
146         return ret;
147 }
148 
149 static struct clocksource kvm_clock = {
150         .name = "kvm-clock",
151         .read = kvm_clock_get_cycles,
152         .rating = 400,
153         .mask = CLOCKSOURCE_MASK(64),
154         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
155 };
156 
157 int kvm_register_clock(char *txt)
158 {
159         int cpu = smp_processor_id();
160         int low, high, ret;
161         struct pvclock_vcpu_time_info *src;
162 
163         if (!hv_clock)
164                 return 0;
165 
166         src = &hv_clock[cpu].pvti;
167         low = (int)slow_virt_to_phys(src) | 1;
168         high = ((u64)slow_virt_to_phys(src) >> 32);
169         ret = native_write_msr_safe(msr_kvm_system_time, low, high);
170         printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
171                cpu, high, low, txt);
172 
173         return ret;
174 }
175 
176 static void kvm_save_sched_clock_state(void)
177 {
178 }
179 
180 static void kvm_restore_sched_clock_state(void)
181 {
182         kvm_register_clock("primary cpu clock, resume");
183 }
184 
185 #ifdef CONFIG_X86_LOCAL_APIC
186 static void kvm_setup_secondary_clock(void)
187 {
188         /*
189          * Now that the first cpu already had this clocksource initialized,
190          * we shouldn't fail.
191          */
192         WARN_ON(kvm_register_clock("secondary cpu clock"));
193 }
194 #endif
195 
196 /*
197  * After the clock is registered, the host will keep writing to the
198  * registered memory location. If the guest happens to shutdown, this memory
199  * won't be valid. In cases like kexec, in which you install a new kernel, this
200  * means a random memory location will be kept being written. So before any
201  * kind of shutdown from our side, we unregister the clock by writting anything
202  * that does not have the 'enable' bit set in the msr
203  */
204 #ifdef CONFIG_KEXEC
205 static void kvm_crash_shutdown(struct pt_regs *regs)
206 {
207         native_write_msr(msr_kvm_system_time, 0, 0);
208         kvm_disable_steal_time();
209         native_machine_crash_shutdown(regs);
210 }
211 #endif
212 
213 static void kvm_shutdown(void)
214 {
215         native_write_msr(msr_kvm_system_time, 0, 0);
216         kvm_disable_steal_time();
217         native_machine_shutdown();
218 }
219 
220 void __init kvmclock_init(void)
221 {
222         unsigned long mem;
223         int size;
224 
225         size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
226 
227         if (!kvm_para_available())
228                 return;
229 
230         if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
231                 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
232                 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
233         } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
234                 return;
235 
236         printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
237                 msr_kvm_system_time, msr_kvm_wall_clock);
238 
239         mem = memblock_alloc(size, PAGE_SIZE);
240         if (!mem)
241                 return;
242         hv_clock = __va(mem);
243         memset(hv_clock, 0, size);
244 
245         if (kvm_register_clock("boot clock")) {
246                 hv_clock = NULL;
247                 memblock_free(mem, size);
248                 return;
249         }
250         pv_time_ops.sched_clock = kvm_clock_read;
251         x86_platform.calibrate_tsc = kvm_get_tsc_khz;
252         x86_platform.get_wallclock = kvm_get_wallclock;
253         x86_platform.set_wallclock = kvm_set_wallclock;
254 #ifdef CONFIG_X86_LOCAL_APIC
255         x86_cpuinit.early_percpu_clock_init =
256                 kvm_setup_secondary_clock;
257 #endif
258         x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
259         x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
260         machine_ops.shutdown  = kvm_shutdown;
261 #ifdef CONFIG_KEXEC
262         machine_ops.crash_shutdown  = kvm_crash_shutdown;
263 #endif
264         kvm_get_preset_lpj();
265         clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
266         pv_info.name = "KVM";
267 
268         if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
269                 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
270 }
271 
272 int __init kvm_setup_vsyscall_timeinfo(void)
273 {
274 #ifdef CONFIG_X86_64
275         int cpu;
276         int ret;
277         u8 flags;
278         struct pvclock_vcpu_time_info *vcpu_time;
279         unsigned int size;
280 
281         if (!hv_clock)
282                 return 0;
283 
284         size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
285 
286         preempt_disable();
287         cpu = smp_processor_id();
288 
289         vcpu_time = &hv_clock[cpu].pvti;
290         flags = pvclock_read_flags(vcpu_time);
291 
292         if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
293                 preempt_enable();
294                 return 1;
295         }
296 
297         if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
298                 preempt_enable();
299                 return ret;
300         }
301 
302         preempt_enable();
303 
304         kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
305 #endif
306         return 0;
307 }
308 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp