1/* 2 * Copyright (C) 2012 ARM Ltd. 3 * Author: Marc Zyngier <marc.zyngier@arm.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 17 */ 18 19#include <linux/cpu.h> 20#include <linux/of_irq.h> 21#include <linux/kvm.h> 22#include <linux/kvm_host.h> 23#include <linux/interrupt.h> 24 25#include <clocksource/arm_arch_timer.h> 26#include <asm/arch_timer.h> 27 28#include <kvm/arm_vgic.h> 29#include <kvm/arm_arch_timer.h> 30 31#include "trace.h" 32 33static struct timecounter *timecounter; 34static struct workqueue_struct *wqueue; 35static unsigned int host_vtimer_irq; 36 37static cycle_t kvm_phys_timer_read(void) 38{ 39 return timecounter->cc->read(timecounter->cc); 40} 41 42static bool timer_is_armed(struct arch_timer_cpu *timer) 43{ 44 return timer->armed; 45} 46 47/* timer_arm: as in "arm the timer", not as in ARM the company */ 48static void timer_arm(struct arch_timer_cpu *timer, u64 ns) 49{ 50 timer->armed = true; 51 hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns), 52 HRTIMER_MODE_ABS); 53} 54 55static void timer_disarm(struct arch_timer_cpu *timer) 56{ 57 if (timer_is_armed(timer)) { 58 hrtimer_cancel(&timer->timer); 59 cancel_work_sync(&timer->expired); 60 timer->armed = false; 61 } 62} 63 64static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id) 65{ 66 struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id; 67 68 /* 69 * We disable the timer in the world switch and let it be 70 * handled by kvm_timer_sync_hwstate(). Getting a timer 71 * interrupt at this point is a sure sign of some major 72 * breakage. 73 */ 74 pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu); 75 return IRQ_HANDLED; 76} 77 78/* 79 * Work function for handling the backup timer that we schedule when a vcpu is 80 * no longer running, but had a timer programmed to fire in the future. 81 */ 82static void kvm_timer_inject_irq_work(struct work_struct *work) 83{ 84 struct kvm_vcpu *vcpu; 85 86 vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired); 87 vcpu->arch.timer_cpu.armed = false; 88 89 WARN_ON(!kvm_timer_should_fire(vcpu)); 90 91 /* 92 * If the vcpu is blocked we want to wake it up so that it will see 93 * the timer has expired when entering the guest. 94 */ 95 kvm_vcpu_kick(vcpu); 96} 97 98static u64 kvm_timer_compute_delta(struct kvm_vcpu *vcpu) 99{ 100 cycle_t cval, now; 101 102 cval = vcpu->arch.timer_cpu.cntv_cval; 103 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; 104 105 if (now < cval) { 106 u64 ns; 107 108 ns = cyclecounter_cyc2ns(timecounter->cc, 109 cval - now, 110 timecounter->mask, 111 &timecounter->frac); 112 return ns; 113 } 114 115 return 0; 116} 117 118static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt) 119{ 120 struct arch_timer_cpu *timer; 121 struct kvm_vcpu *vcpu; 122 u64 ns; 123 124 timer = container_of(hrt, struct arch_timer_cpu, timer); 125 vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu); 126 127 /* 128 * Check that the timer has really expired from the guest's 129 * PoV (NTP on the host may have forced it to expire 130 * early). If we should have slept longer, restart it. 131 */ 132 ns = kvm_timer_compute_delta(vcpu); 133 if (unlikely(ns)) { 134 hrtimer_forward_now(hrt, ns_to_ktime(ns)); 135 return HRTIMER_RESTART; 136 } 137 138 queue_work(wqueue, &timer->expired); 139 return HRTIMER_NORESTART; 140} 141 142static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu) 143{ 144 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 145 146 return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) && 147 (timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE); 148} 149 150bool kvm_timer_should_fire(struct kvm_vcpu *vcpu) 151{ 152 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 153 cycle_t cval, now; 154 155 if (!kvm_timer_irq_can_fire(vcpu)) 156 return false; 157 158 cval = timer->cntv_cval; 159 now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; 160 161 return cval <= now; 162} 163 164static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level) 165{ 166 int ret; 167 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 168 169 BUG_ON(!vgic_initialized(vcpu->kvm)); 170 171 timer->irq.level = new_level; 172 trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->map->virt_irq, 173 timer->irq.level); 174 ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id, 175 timer->map, 176 timer->irq.level); 177 WARN_ON(ret); 178} 179 180/* 181 * Check if there was a change in the timer state (should we raise or lower 182 * the line level to the GIC). 183 */ 184static int kvm_timer_update_state(struct kvm_vcpu *vcpu) 185{ 186 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 187 188 /* 189 * If userspace modified the timer registers via SET_ONE_REG before 190 * the vgic was initialized, we mustn't set the timer->irq.level value 191 * because the guest would never see the interrupt. Instead wait 192 * until we call this function from kvm_timer_flush_hwstate. 193 */ 194 if (!vgic_initialized(vcpu->kvm)) 195 return -ENODEV; 196 197 if (kvm_timer_should_fire(vcpu) != timer->irq.level) 198 kvm_timer_update_irq(vcpu, !timer->irq.level); 199 200 return 0; 201} 202 203/* 204 * Schedule the background timer before calling kvm_vcpu_block, so that this 205 * thread is removed from its waitqueue and made runnable when there's a timer 206 * interrupt to handle. 207 */ 208void kvm_timer_schedule(struct kvm_vcpu *vcpu) 209{ 210 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 211 212 BUG_ON(timer_is_armed(timer)); 213 214 /* 215 * No need to schedule a background timer if the guest timer has 216 * already expired, because kvm_vcpu_block will return before putting 217 * the thread to sleep. 218 */ 219 if (kvm_timer_should_fire(vcpu)) 220 return; 221 222 /* 223 * If the timer is not capable of raising interrupts (disabled or 224 * masked), then there's no more work for us to do. 225 */ 226 if (!kvm_timer_irq_can_fire(vcpu)) 227 return; 228 229 /* The timer has not yet expired, schedule a background timer */ 230 timer_arm(timer, kvm_timer_compute_delta(vcpu)); 231} 232 233void kvm_timer_unschedule(struct kvm_vcpu *vcpu) 234{ 235 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 236 timer_disarm(timer); 237} 238 239/** 240 * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu 241 * @vcpu: The vcpu pointer 242 * 243 * Check if the virtual timer has expired while we were running in the host, 244 * and inject an interrupt if that was the case. 245 */ 246void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) 247{ 248 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 249 bool phys_active; 250 int ret; 251 252 if (kvm_timer_update_state(vcpu)) 253 return; 254 255 /* 256 * If we enter the guest with the virtual input level to the VGIC 257 * asserted, then we have already told the VGIC what we need to, and 258 * we don't need to exit from the guest until the guest deactivates 259 * the already injected interrupt, so therefore we should set the 260 * hardware active state to prevent unnecessary exits from the guest. 261 * 262 * Also, if we enter the guest with the virtual timer interrupt active, 263 * then it must be active on the physical distributor, because we set 264 * the HW bit and the guest must be able to deactivate the virtual and 265 * physical interrupt at the same time. 266 * 267 * Conversely, if the virtual input level is deasserted and the virtual 268 * interrupt is not active, then always clear the hardware active state 269 * to ensure that hardware interrupts from the timer triggers a guest 270 * exit. 271 */ 272 if (timer->irq.level || kvm_vgic_map_is_active(vcpu, timer->map)) 273 phys_active = true; 274 else 275 phys_active = false; 276 277 ret = irq_set_irqchip_state(timer->map->irq, 278 IRQCHIP_STATE_ACTIVE, 279 phys_active); 280 WARN_ON(ret); 281} 282 283/** 284 * kvm_timer_sync_hwstate - sync timer state from cpu 285 * @vcpu: The vcpu pointer 286 * 287 * Check if the virtual timer has expired while we were running in the guest, 288 * and inject an interrupt if that was the case. 289 */ 290void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) 291{ 292 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 293 294 BUG_ON(timer_is_armed(timer)); 295 296 /* 297 * The guest could have modified the timer registers or the timer 298 * could have expired, update the timer state. 299 */ 300 kvm_timer_update_state(vcpu); 301} 302 303int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu, 304 const struct kvm_irq_level *irq) 305{ 306 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 307 struct irq_phys_map *map; 308 309 /* 310 * The vcpu timer irq number cannot be determined in 311 * kvm_timer_vcpu_init() because it is called much before 312 * kvm_vcpu_set_target(). To handle this, we determine 313 * vcpu timer irq number when the vcpu is reset. 314 */ 315 timer->irq.irq = irq->irq; 316 317 /* 318 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8 319 * and to 0 for ARMv7. We provide an implementation that always 320 * resets the timer to be disabled and unmasked and is compliant with 321 * the ARMv7 architecture. 322 */ 323 timer->cntv_ctl = 0; 324 kvm_timer_update_state(vcpu); 325 326 /* 327 * Tell the VGIC that the virtual interrupt is tied to a 328 * physical interrupt. We do that once per VCPU. 329 */ 330 map = kvm_vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq); 331 if (WARN_ON(IS_ERR(map))) 332 return PTR_ERR(map); 333 334 timer->map = map; 335 return 0; 336} 337 338void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) 339{ 340 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 341 342 INIT_WORK(&timer->expired, kvm_timer_inject_irq_work); 343 hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); 344 timer->timer.function = kvm_timer_expire; 345} 346 347static void kvm_timer_init_interrupt(void *info) 348{ 349 enable_percpu_irq(host_vtimer_irq, 0); 350} 351 352int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value) 353{ 354 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 355 356 switch (regid) { 357 case KVM_REG_ARM_TIMER_CTL: 358 timer->cntv_ctl = value; 359 break; 360 case KVM_REG_ARM_TIMER_CNT: 361 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value; 362 break; 363 case KVM_REG_ARM_TIMER_CVAL: 364 timer->cntv_cval = value; 365 break; 366 default: 367 return -1; 368 } 369 370 kvm_timer_update_state(vcpu); 371 return 0; 372} 373 374u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid) 375{ 376 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 377 378 switch (regid) { 379 case KVM_REG_ARM_TIMER_CTL: 380 return timer->cntv_ctl; 381 case KVM_REG_ARM_TIMER_CNT: 382 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; 383 case KVM_REG_ARM_TIMER_CVAL: 384 return timer->cntv_cval; 385 } 386 return (u64)-1; 387} 388 389static int kvm_timer_cpu_notify(struct notifier_block *self, 390 unsigned long action, void *cpu) 391{ 392 switch (action) { 393 case CPU_STARTING: 394 case CPU_STARTING_FROZEN: 395 kvm_timer_init_interrupt(NULL); 396 break; 397 case CPU_DYING: 398 case CPU_DYING_FROZEN: 399 disable_percpu_irq(host_vtimer_irq); 400 break; 401 } 402 403 return NOTIFY_OK; 404} 405 406static struct notifier_block kvm_timer_cpu_nb = { 407 .notifier_call = kvm_timer_cpu_notify, 408}; 409 410static const struct of_device_id arch_timer_of_match[] = { 411 { .compatible = "arm,armv7-timer", }, 412 { .compatible = "arm,armv8-timer", }, 413 {}, 414}; 415 416int kvm_timer_hyp_init(void) 417{ 418 struct device_node *np; 419 unsigned int ppi; 420 int err; 421 422 timecounter = arch_timer_get_timecounter(); 423 if (!timecounter) 424 return -ENODEV; 425 426 np = of_find_matching_node(NULL, arch_timer_of_match); 427 if (!np) { 428 kvm_err("kvm_arch_timer: can't find DT node\n"); 429 return -ENODEV; 430 } 431 432 ppi = irq_of_parse_and_map(np, 2); 433 if (!ppi) { 434 kvm_err("kvm_arch_timer: no virtual timer interrupt\n"); 435 err = -EINVAL; 436 goto out; 437 } 438 439 err = request_percpu_irq(ppi, kvm_arch_timer_handler, 440 "kvm guest timer", kvm_get_running_vcpus()); 441 if (err) { 442 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n", 443 ppi, err); 444 goto out; 445 } 446 447 host_vtimer_irq = ppi; 448 449 err = __register_cpu_notifier(&kvm_timer_cpu_nb); 450 if (err) { 451 kvm_err("Cannot register timer CPU notifier\n"); 452 goto out_free; 453 } 454 455 wqueue = create_singlethread_workqueue("kvm_arch_timer"); 456 if (!wqueue) { 457 err = -ENOMEM; 458 goto out_free; 459 } 460 461 kvm_info("%s IRQ%d\n", np->name, ppi); 462 on_each_cpu(kvm_timer_init_interrupt, NULL, 1); 463 464 goto out; 465out_free: 466 free_percpu_irq(ppi, kvm_get_running_vcpus()); 467out: 468 of_node_put(np); 469 return err; 470} 471 472void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) 473{ 474 struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; 475 476 timer_disarm(timer); 477 if (timer->map) 478 kvm_vgic_unmap_phys_irq(vcpu, timer->map); 479} 480 481void kvm_timer_enable(struct kvm *kvm) 482{ 483 if (kvm->arch.timer.enabled) 484 return; 485 486 /* 487 * There is a potential race here between VCPUs starting for the first 488 * time, which may be enabling the timer multiple times. That doesn't 489 * hurt though, because we're just setting a variable to the same 490 * variable that it already was. The important thing is that all 491 * VCPUs have the enabled variable set, before entering the guest, if 492 * the arch timers are enabled. 493 */ 494 if (timecounter && wqueue) 495 kvm->arch.timer.enabled = 1; 496} 497 498void kvm_timer_init(struct kvm *kvm) 499{ 500 kvm->arch.timer.cntvoff = kvm_phys_timer_read(); 501} 502