kernel/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         timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
  68         ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
  69                                   timer->irq->irq,
  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                 return false;
 122
 123         cval = timer->cntv_cval;
 124         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 125
 126         return cval <= now;
 127 }
 128
 129 /**
 130  * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
 131  * @vcpu: The vcpu pointer
 132  *
 133  * Disarm any pending soft timers, since the world-switch code will write the
 134  * virtual timer state back to the physical CPU.
 135  */
 136 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 137 {
 138         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 139
 140         /*
 141          * We're about to run this vcpu again, so there is no need to
 142          * keep the background timer running, as we're about to
 143          * populate the CPU timer again.
 144          */
 145         timer_disarm(timer);
 146
 147         /*
 148          * If the timer expired while we were not scheduled, now is the time
 149          * to inject it.
 150          */
 151         if (kvm_timer_should_fire(vcpu))
 152                 kvm_timer_inject_irq(vcpu);
 153 }
 154
 155 /**
 156  * kvm_timer_sync_hwstate - sync timer state from cpu
 157  * @vcpu: The vcpu pointer
 158  *
 159  * Check if the virtual timer was armed and either schedule a corresponding
 160  * soft timer or inject directly if already expired.
 161  */
 162 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 163 {
 164         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 165         cycle_t cval, now;
 166         u64 ns;
 167
 168         BUG_ON(timer_is_armed(timer));
 169
 170         if (kvm_timer_should_fire(vcpu)) {
 171                 /*
 172                  * Timer has already expired while we were not
 173                  * looking. Inject the interrupt and carry on.
 174                  */
 175                 kvm_timer_inject_irq(vcpu);
 176                 return;
 177         }
 178
 179         cval = timer->cntv_cval;
 180         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 181
 182         ns = cyclecounter_cyc2ns(timecounter->cc, cval - now, timecounter->mask,
 183                                  &timecounter->frac);
 184         timer_arm(timer, ns);
 185 }
 186
 187 void kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 188                           const struct kvm_irq_level *irq)
 189 {
 190         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 191
 192         /*
 193          * The vcpu timer irq number cannot be determined in
 194          * kvm_timer_vcpu_init() because it is called much before
 195          * kvm_vcpu_set_target(). To handle this, we determine
 196          * vcpu timer irq number when the vcpu is reset.
 197          */
 198         timer->irq = irq;
 199 }
 200
 201 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 202 {
 203         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 204
 205         INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
 206         hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 207         timer->timer.function = kvm_timer_expire;
 208 }
 209
 210 static void kvm_timer_init_interrupt(void *info)
 211 {
 212         enable_percpu_irq(host_vtimer_irq, 0);
 213 }
 214
 215 int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
 216 {
 217         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 218
 219         switch (regid) {
 220         case KVM_REG_ARM_TIMER_CTL:
 221                 timer->cntv_ctl = value;
 222                 break;
 223         case KVM_REG_ARM_TIMER_CNT:
 224                 vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - value;
 225                 break;
 226         case KVM_REG_ARM_TIMER_CVAL:
 227                 timer->cntv_cval = value;
 228                 break;
 229         default:
 230                 return -1;
 231         }
 232         return 0;
 233 }
 234
 235 u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
 236 {
 237         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 238
 239         switch (regid) {
 240         case KVM_REG_ARM_TIMER_CTL:
 241                 return timer->cntv_ctl;
 242         case KVM_REG_ARM_TIMER_CNT:
 243                 return kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 244         case KVM_REG_ARM_TIMER_CVAL:
 245                 return timer->cntv_cval;
 246         }
 247         return (u64)-1;
 248 }
 249
 250 static int kvm_timer_cpu_notify(struct notifier_block *self,
 251                                 unsigned long action, void *cpu)
 252 {
 253         switch (action) {
 254         case CPU_STARTING:
 255         case CPU_STARTING_FROZEN:
 256                 kvm_timer_init_interrupt(NULL);
 257                 break;
 258         case CPU_DYING:
 259         case CPU_DYING_FROZEN:
 260                 disable_percpu_irq(host_vtimer_irq);
 261                 break;
 262         }
 263
 264         return NOTIFY_OK;
 265 }
 266
 267 static struct notifier_block kvm_timer_cpu_nb = {
 268         .notifier_call = kvm_timer_cpu_notify,
 269 };
 270
 271 static const struct of_device_id arch_timer_of_match[] = {
 272         { .compatible   = "arm,armv7-timer",    },
 273         { .compatible   = "arm,armv8-timer",    },
 274         {},
 275 };
 276
 277 int kvm_timer_hyp_init(void)
 278 {
 279         struct device_node *np;
 280         unsigned int ppi;
 281         int err;
 282
 283         timecounter = arch_timer_get_timecounter();
 284         if (!timecounter)
 285                 return -ENODEV;
 286
 287         np = of_find_matching_node(NULL, arch_timer_of_match);
 288         if (!np) {
 289                 kvm_err("kvm_arch_timer: can't find DT node\n");
 290                 return -ENODEV;
 291         }
 292
 293         ppi = irq_of_parse_and_map(np, 2);
 294         if (!ppi) {
 295                 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
 296                 err = -EINVAL;
 297                 goto out;
 298         }
 299
 300         err = request_percpu_irq(ppi, kvm_arch_timer_handler,
 301                                  "kvm guest timer", kvm_get_running_vcpus());
 302         if (err) {
 303                 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
 304                         ppi, err);
 305                 goto out;
 306         }
 307
 308         host_vtimer_irq = ppi;
 309
 310         err = __register_cpu_notifier(&kvm_timer_cpu_nb);
 311         if (err) {
 312                 kvm_err("Cannot register timer CPU notifier\n");
 313                 goto out_free;
 314         }
 315
 316         wqueue = create_singlethread_workqueue("kvm_arch_timer");
 317         if (!wqueue) {
 318                 err = -ENOMEM;
 319                 goto out_free;
 320         }
 321
 322         kvm_info("%s IRQ%d\n", np->name, ppi);
 323         on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 324
 325         goto out;
 326 out_free:
 327         free_percpu_irq(ppi, kvm_get_running_vcpus());
 328 out:
 329         of_node_put(np);
 330         return err;
 331 }
 332
 333 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 334 {
 335         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 336
 337         timer_disarm(timer);
 338 }
 339
 340 void kvm_timer_enable(struct kvm *kvm)
 341 {
 342         if (kvm->arch.timer.enabled)
 343                 return;
 344
 345         /*
 346          * There is a potential race here between VCPUs starting for the first
 347          * time, which may be enabling the timer multiple times.  That doesn't
 348          * hurt though, because we're just setting a variable to the same
 349          * variable that it already was.  The important thing is that all
 350          * VCPUs have the enabled variable set, before entering the guest, if
 351          * the arch timers are enabled.
 352          */
 353         if (timecounter && wqueue)
 354                 kvm->arch.timer.enabled = 1;
 355 }
 356
 357 void kvm_timer_init(struct kvm *kvm)
 358 {
 359         kvm->arch.timer.cntvoff = kvm_phys_timer_read();
 360 }