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 #include <linux/sched.h> 28 #include <linux/sched/clock.h> 29 30 #include <asm/mem_encrypt.h> 31 #include <asm/x86_init.h> 32 #include <asm/reboot.h> 33 #include <asm/kvmclock.h> 34 35 static int kvmclock __ro_after_init = 1; 36 static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME; 37 static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK; 38 static u64 kvm_sched_clock_offset; 39 40 static int parse_no_kvmclock(char *arg) 41 { 42 kvmclock = 0; 43 return 0; 44 } 45 early_param("no-kvmclock", parse_no_kvmclock); 46 47 /* The hypervisor will put information about time periodically here */ 48 static struct pvclock_vsyscall_time_info *hv_clock; 49 static struct pvclock_wall_clock *wall_clock; 50 51 /* 52 * The wallclock is the time of day when we booted. Since then, some time may 53 * have elapsed since the hypervisor wrote the data. So we try to account for 54 * that with system time 55 */ 56 static void kvm_get_wallclock(struct timespec *now) 57 { 58 struct pvclock_vcpu_time_info *vcpu_time; 59 int low, high; 60 int cpu; 61 62 low = (int)slow_virt_to_phys(wall_clock); 63 high = ((u64)slow_virt_to_phys(wall_clock) >> 32); 64 65 native_write_msr(msr_kvm_wall_clock, low, high); 66 67 cpu = get_cpu(); 68 69 vcpu_time = &hv_clock[cpu].pvti; 70 pvclock_read_wallclock(wall_clock, vcpu_time, now); 71 72 put_cpu(); 73 } 74 75 static int kvm_set_wallclock(const struct timespec *now) 76 { 77 return -ENODEV; 78 } 79 80 static u64 kvm_clock_read(void) 81 { 82 struct pvclock_vcpu_time_info *src; 83 u64 ret; 84 int cpu; 85 86 preempt_disable_notrace(); 87 cpu = smp_processor_id(); 88 src = &hv_clock[cpu].pvti; 89 ret = pvclock_clocksource_read(src); 90 preempt_enable_notrace(); 91 return ret; 92 } 93 94 static u64 kvm_clock_get_cycles(struct clocksource *cs) 95 { 96 return kvm_clock_read(); 97 } 98 99 static u64 kvm_sched_clock_read(void) 100 { 101 return kvm_clock_read() - kvm_sched_clock_offset; 102 } 103 104 static inline void kvm_sched_clock_init(bool stable) 105 { 106 if (!stable) { 107 pv_time_ops.sched_clock = kvm_clock_read; 108 clear_sched_clock_stable(); 109 return; 110 } 111 112 kvm_sched_clock_offset = kvm_clock_read(); 113 pv_time_ops.sched_clock = kvm_sched_clock_read; 114 115 printk(KERN_INFO "kvm-clock: using sched offset of %llu cycles\n", 116 kvm_sched_clock_offset); 117 118 BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) > 119 sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time)); 120 } 121 122 /* 123 * If we don't do that, there is the possibility that the guest 124 * will calibrate under heavy load - thus, getting a lower lpj - 125 * and execute the delays themselves without load. This is wrong, 126 * because no delay loop can finish beforehand. 127 * Any heuristics is subject to fail, because ultimately, a large 128 * poll of guests can be running and trouble each other. So we preset 129 * lpj here 130 */ 131 static unsigned long kvm_get_tsc_khz(void) 132 { 133 struct pvclock_vcpu_time_info *src; 134 int cpu; 135 unsigned long tsc_khz; 136 137 cpu = get_cpu(); 138 src = &hv_clock[cpu].pvti; 139 tsc_khz = pvclock_tsc_khz(src); 140 put_cpu(); 141 return tsc_khz; 142 } 143 144 static void kvm_get_preset_lpj(void) 145 { 146 unsigned long khz; 147 u64 lpj; 148 149 khz = kvm_get_tsc_khz(); 150 151 lpj = ((u64)khz * 1000); 152 do_div(lpj, HZ); 153 preset_lpj = lpj; 154 } 155 156 bool kvm_check_and_clear_guest_paused(void) 157 { 158 bool ret = false; 159 struct pvclock_vcpu_time_info *src; 160 int cpu = smp_processor_id(); 161 162 if (!hv_clock) 163 return ret; 164 165 src = &hv_clock[cpu].pvti; 166 if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) { 167 src->flags &= ~PVCLOCK_GUEST_STOPPED; 168 pvclock_touch_watchdogs(); 169 ret = true; 170 } 171 172 return ret; 173 } 174 175 struct clocksource kvm_clock = { 176 .name = "kvm-clock", 177 .read = kvm_clock_get_cycles, 178 .rating = 400, 179 .mask = CLOCKSOURCE_MASK(64), 180 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 181 }; 182 EXPORT_SYMBOL_GPL(kvm_clock); 183 184 int kvm_register_clock(char *txt) 185 { 186 int cpu = smp_processor_id(); 187 int low, high, ret; 188 struct pvclock_vcpu_time_info *src; 189 190 if (!hv_clock) 191 return 0; 192 193 src = &hv_clock[cpu].pvti; 194 low = (int)slow_virt_to_phys(src) | 1; 195 high = ((u64)slow_virt_to_phys(src) >> 32); 196 ret = native_write_msr_safe(msr_kvm_system_time, low, high); 197 printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n", 198 cpu, high, low, txt); 199 200 return ret; 201 } 202 203 static void kvm_save_sched_clock_state(void) 204 { 205 } 206 207 static void kvm_restore_sched_clock_state(void) 208 { 209 kvm_register_clock("primary cpu clock, resume"); 210 } 211 212 #ifdef CONFIG_X86_LOCAL_APIC 213 static void kvm_setup_secondary_clock(void) 214 { 215 /* 216 * Now that the first cpu already had this clocksource initialized, 217 * we shouldn't fail. 218 */ 219 WARN_ON(kvm_register_clock("secondary cpu clock")); 220 } 221 #endif 222 223 /* 224 * After the clock is registered, the host will keep writing to the 225 * registered memory location. If the guest happens to shutdown, this memory 226 * won't be valid. In cases like kexec, in which you install a new kernel, this 227 * means a random memory location will be kept being written. So before any 228 * kind of shutdown from our side, we unregister the clock by writing anything 229 * that does not have the 'enable' bit set in the msr 230 */ 231 #ifdef CONFIG_KEXEC_CORE 232 static void kvm_crash_shutdown(struct pt_regs *regs) 233 { 234 native_write_msr(msr_kvm_system_time, 0, 0); 235 kvm_disable_steal_time(); 236 native_machine_crash_shutdown(regs); 237 } 238 #endif 239 240 static void kvm_shutdown(void) 241 { 242 native_write_msr(msr_kvm_system_time, 0, 0); 243 kvm_disable_steal_time(); 244 native_machine_shutdown(); 245 } 246 247 static phys_addr_t __init kvm_memblock_alloc(phys_addr_t size, 248 phys_addr_t align) 249 { 250 phys_addr_t mem; 251 252 mem = memblock_alloc(size, align); 253 if (!mem) 254 return 0; 255 256 if (sev_active()) { 257 if (early_set_memory_decrypted((unsigned long)__va(mem), size)) 258 goto e_free; 259 } 260 261 return mem; 262 e_free: 263 memblock_free(mem, size); 264 return 0; 265 } 266 267 static void __init kvm_memblock_free(phys_addr_t addr, phys_addr_t size) 268 { 269 if (sev_active()) 270 early_set_memory_encrypted((unsigned long)__va(addr), size); 271 272 memblock_free(addr, size); 273 } 274 275 void __init kvmclock_init(void) 276 { 277 struct pvclock_vcpu_time_info *vcpu_time; 278 unsigned long mem, mem_wall_clock; 279 int size, cpu, wall_clock_size; 280 u8 flags; 281 282 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS); 283 284 if (!kvm_para_available()) 285 return; 286 287 if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { 288 msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; 289 msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; 290 } else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE))) 291 return; 292 293 wall_clock_size = PAGE_ALIGN(sizeof(struct pvclock_wall_clock)); 294 mem_wall_clock = kvm_memblock_alloc(wall_clock_size, PAGE_SIZE); 295 if (!mem_wall_clock) 296 return; 297 298 wall_clock = __va(mem_wall_clock); 299 memset(wall_clock, 0, wall_clock_size); 300 301 mem = kvm_memblock_alloc(size, PAGE_SIZE); 302 if (!mem) { 303 kvm_memblock_free(mem_wall_clock, wall_clock_size); 304 wall_clock = NULL; 305 return; 306 } 307 308 hv_clock = __va(mem); 309 memset(hv_clock, 0, size); 310 311 if (kvm_register_clock("primary cpu clock")) { 312 hv_clock = NULL; 313 kvm_memblock_free(mem, size); 314 kvm_memblock_free(mem_wall_clock, wall_clock_size); 315 wall_clock = NULL; 316 return; 317 } 318 319 printk(KERN_INFO "kvm-clock: Using msrs %x and %x", 320 msr_kvm_system_time, msr_kvm_wall_clock); 321 322 if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) 323 pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); 324 325 cpu = get_cpu(); 326 vcpu_time = &hv_clock[cpu].pvti; 327 flags = pvclock_read_flags(vcpu_time); 328 329 kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); 330 put_cpu(); 331 332 x86_platform.calibrate_tsc = kvm_get_tsc_khz; 333 x86_platform.calibrate_cpu = kvm_get_tsc_khz; 334 x86_platform.get_wallclock = kvm_get_wallclock; 335 x86_platform.set_wallclock = kvm_set_wallclock; 336 #ifdef CONFIG_X86_LOCAL_APIC 337 x86_cpuinit.early_percpu_clock_init = 338 kvm_setup_secondary_clock; 339 #endif 340 x86_platform.save_sched_clock_state = kvm_save_sched_clock_state; 341 x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state; 342 machine_ops.shutdown = kvm_shutdown; 343 #ifdef CONFIG_KEXEC_CORE 344 machine_ops.crash_shutdown = kvm_crash_shutdown; 345 #endif 346 kvm_get_preset_lpj(); 347 clocksource_register_hz(&kvm_clock, NSEC_PER_SEC); 348 pv_info.name = "KVM"; 349 } 350 351 int __init kvm_setup_vsyscall_timeinfo(void) 352 { 353 #ifdef CONFIG_X86_64 354 int cpu; 355 u8 flags; 356 struct pvclock_vcpu_time_info *vcpu_time; 357 unsigned int size; 358 359 if (!hv_clock) 360 return 0; 361 362 size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS); 363 364 cpu = get_cpu(); 365 366 vcpu_time = &hv_clock[cpu].pvti; 367 flags = pvclock_read_flags(vcpu_time); 368 369 if (!(flags & PVCLOCK_TSC_STABLE_BIT)) { 370 put_cpu(); 371 return 1; 372 } 373 374 pvclock_set_pvti_cpu0_va(hv_clock); 375 put_cpu(); 376 377 kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK; 378 #endif 379 return 0; 380 } 381