virt/kvm/arm/arch_timer.c

   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 static struct timecounter *timecounter;
  32 static struct workqueue_struct *wqueue;
  33 static unsigned int host_vtimer_irq;
  34
  35 static cycle_t kvm_phys_timer_read(void)
  36 {
  37         return timecounter->cc->read(timecounter->cc);
  38 }
  39
  40 static bool timer_is_armed(struct arch_timer_cpu *timer)
  41 {
  42         return timer->armed;
  43 }
  44
  45 /* timer_arm: as in "arm the timer", not as in ARM the company */
  46 static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
  47 {
  48         timer->armed = true;
  49         hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
  50                       HRTIMER_MODE_ABS);
  51 }
  52
  53 static void timer_disarm(struct arch_timer_cpu *timer)
  54 {
  55         if (timer_is_armed(timer)) {
  56                 hrtimer_cancel(&timer->timer);
  57                 cancel_work_sync(&timer->expired);
  58                 timer->armed = false;
  59         }
  60 }
  61
  62 static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
  63 {
  64         int ret;
  65         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
  66
  67         kvm_vgic_set_phys_irq_active(timer->map, true);
  68         ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
  69                                          timer->map,
  70                                          timer->irq->level);
  71         WARN_ON(ret);
  72 }
  73
  74 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
  75 {
  76         struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
  77
  78         /*
  79          * We disable the timer in the world switch and let it be
  80          * handled by kvm_timer_sync_hwstate(). Getting a timer
  81          * interrupt at this point is a sure sign of some major
  82          * breakage.
  83          */
  84         pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
  85         return IRQ_HANDLED;
  86 }
  87
  88 /*
  89  * Work function for handling the backup timer that we schedule when a vcpu is
  90  * no longer running, but had a timer programmed to fire in the future.
  91  */
  92 static void kvm_timer_inject_irq_work(struct work_struct *work)
  93 {
  94         struct kvm_vcpu *vcpu;
  95
  96         vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
  97         vcpu->arch.timer_cpu.armed = false;
  98
  99         /*
 100          * If the vcpu is blocked we want to wake it up so that it will see
 101          * the timer has expired when entering the guest.
 102          */
 103         kvm_vcpu_kick(vcpu);
 104 }
 105
 106 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
 107 {
 108         struct arch_timer_cpu *timer;
 109         timer = container_of(hrt, struct arch_timer_cpu, timer);
 110         queue_work(wqueue, &timer->expired);
 111         return HRTIMER_NORESTART;
 112 }
 113
 114 bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
 115 {
 116         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 117         cycle_t cval, now;
 118
 119         if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) ||
 120             !(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE) ||
 121             kvm_vgic_get_phys_irq_active(timer->map))
 122                 return false;
 123
 124         cval = timer->cntv_cval;
 125         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 126
 127         return cval <= now;
 128 }
 129
 130 /**
 131  * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
 132  * @vcpu: The vcpu pointer
 133  *
 134  * Disarm any pending soft timers, since the world-switch code will write the
 135  * virtual timer state back to the physical CPU.
 136  */
 137 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 138 {
 139         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 140
 141         /*
 142          * We're about to run this vcpu again, so there is no need to
 143          * keep the background timer running, as we're about to
 144          * populate the CPU timer again.
 145          */
 146         timer_disarm(timer);
 147
 148         /*
 149          * If the timer expired while we were not scheduled, now is the time
 150          * to inject it.
 151          */
 152         if (kvm_timer_should_fire(vcpu))
 153                 kvm_timer_inject_irq(vcpu);
 154 }
 155
 156 /**
 157  * kvm_timer_sync_hwstate - sync timer state from cpu
 158  * @vcpu: The vcpu pointer
 159  *
 160  * Check if the virtual timer was armed and either schedule a corresponding
 161  * soft timer or inject directly if already expired.
 162  */
 163 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 164 {
 165         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 166         cycle_t cval, now;
 167         u64 ns;
 168
 169         BUG_ON(timer_is_armed(timer));
 170
 171         if (kvm_timer_should_fire(vcpu)) {
 172                 /*
 173                  * Timer has already expired while we were not
 174                  * looking. Inject the interrupt and carry on.
 175                  */
 176                 kvm_timer_inject_irq(vcpu);
 177                 return;
 178         }
 179
 180         cval = timer->cntv_cval;
 181         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 182
 183         ns = cyclecounter_cyc2ns(timecounter->cc, cval - now, timecounter->mask,
 184                                  &timecounter->frac);
 185         timer_arm(timer, ns);
 186 }
 187
 188 int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 189                          const struct kvm_irq_level *irq)
 190 {
 191         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 192         struct irq_phys_map *map;
 193
 194         /*
 195          * The vcpu timer irq number cannot be determined in
 196          * kvm_timer_vcpu_init() because it is called much before
 197          * kvm_vcpu_set_target(). To handle this, we determine
 198          * vcpu timer irq number when the vcpu is reset.
 199          */
 200         timer->irq = irq;
 201
 202         /*
 203          * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
 204          * and to 0 for ARMv7.  We provide an implementation that always
 205          * resets the timer to be disabled and unmasked and is compliant with
 206          * the ARMv7 architecture.
 207          */
 208         timer->cntv_ctl = 0;
 209
 210         /*
 211          * Tell the VGIC that the virtual interrupt is tied to a
 212          * physical interrupt. We do that once per VCPU.
 213          */
 214         map = kvm_vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq);
 215         if (WARN_ON(IS_ERR(map)))
 216                 return PTR_ERR(map);
 217
 218         timer->map = map;
 219         return 0;
 220 }
 221
 222 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 223 {
 224         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 225
 226         INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
 227         hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 228         timer->timer.function = kvm_timer_expire;
 229 }
 230
 231 static void kvm_timer_init_interrupt(void *info)
 232 {
 233         enable_percpu_irq(host_vtimer_irq, 0);
 234 }
 235
 236 int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
 237 {
 238         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 239
 240         switch (regid) {
 241         case KVM_REG_ARM_TIMER_CTL:
 242                 timer->cntv_ctl = value;
 243                 break;
 244         case KVM_REG_ARM_TIMER_CNT:
 245                 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
 246                 break;
 247         case KVM_REG_ARM_TIMER_CVAL:
 248                 timer->cntv_cval = value;
 249                 break;
 250         default:
 251                 return -1;
 252         }
 253         return 0;
 254 }
 255
 256 u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
 257 {
 258         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 259
 260         switch (regid) {
 261         case KVM_REG_ARM_TIMER_CTL:
 262                 return timer->cntv_ctl;
 263         case KVM_REG_ARM_TIMER_CNT:
 264                 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 265         case KVM_REG_ARM_TIMER_CVAL:
 266                 return timer->cntv_cval;
 267         }
 268         return (u64)-1;
 269 }
 270
 271 static int kvm_timer_cpu_notify(struct notifier_block *self,
 272                                 unsigned long action, void *cpu)
 273 {
 274         switch (action) {
 275         case CPU_STARTING:
 276         case CPU_STARTING_FROZEN:
 277                 kvm_timer_init_interrupt(NULL);
 278                 break;
 279         case CPU_DYING:
 280         case CPU_DYING_FROZEN:
 281                 disable_percpu_irq(host_vtimer_irq);
 282                 break;
 283         }
 284
 285         return NOTIFY_OK;
 286 }
 287
 288 static struct notifier_block kvm_timer_cpu_nb = {
 289         .notifier_call = kvm_timer_cpu_notify,
 290 };
 291
 292 static const struct of_device_id arch_timer_of_match[] = {
 293         { .compatible   = "arm,armv7-timer",    },
 294         { .compatible   = "arm,armv8-timer",    },
 295         {},
 296 };
 297
 298 int kvm_timer_hyp_init(void)
 299 {
 300         struct device_node *np;
 301         unsigned int ppi;
 302         int err;
 303
 304         timecounter = arch_timer_get_timecounter();
 305         if (!timecounter)
 306                 return -ENODEV;
 307
 308         np = of_find_matching_node(NULL, arch_timer_of_match);
 309         if (!np) {
 310                 kvm_err("kvm_arch_timer: can't find DT node\n");
 311                 return -ENODEV;
 312         }
 313
 314         ppi = irq_of_parse_and_map(np, 2);
 315         if (!ppi) {
 316                 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
 317                 err = -EINVAL;
 318                 goto out;
 319         }
 320
 321         err = request_percpu_irq(ppi, kvm_arch_timer_handler,
 322                                  "kvm guest timer", kvm_get_running_vcpus());
 323         if (err) {
 324                 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
 325                         ppi, err);
 326                 goto out;
 327         }
 328
 329         host_vtimer_irq = ppi;
 330
 331         err = __register_cpu_notifier(&kvm_timer_cpu_nb);
 332         if (err) {
 333                 kvm_err("Cannot register timer CPU notifier\n");
 334                 goto out_free;
 335         }
 336
 337         wqueue = create_singlethread_workqueue("kvm_arch_timer");
 338         if (!wqueue) {
 339                 err = -ENOMEM;
 340                 goto out_free;
 341         }
 342
 343         kvm_info("%s IRQ%d\n", np->name, ppi);
 344         on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 345
 346         goto out;
 347 out_free:
 348         free_percpu_irq(ppi, kvm_get_running_vcpus());
 349 out:
 350         of_node_put(np);
 351         return err;
 352 }
 353
 354 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 355 {
 356         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 357
 358         timer_disarm(timer);
 359         if (timer->map)
 360                 kvm_vgic_unmap_phys_irq(vcpu, timer->map);
 361 }
 362
 363 void kvm_timer_enable(struct kvm *kvm)
 364 {
 365         if (kvm->arch.timer.enabled)
 366                 return;
 367
 368         /*
 369          * There is a potential race here between VCPUs starting for the first
 370          * time, which may be enabling the timer multiple times.  That doesn't
 371          * hurt though, because we're just setting a variable to the same
 372          * variable that it already was.  The important thing is that all
 373          * VCPUs have the enabled variable set, before entering the guest, if
 374          * the arch timers are enabled.
 375          */
 376         if (timecounter && wqueue)
 377                 kvm->arch.timer.enabled = 1;
 378 }
 379
 380 void kvm_timer_init(struct kvm *kvm)
 381 {
 382         kvm->arch.timer.cntvoff = kvm_phys_timer_read();
 383 }