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 static void kvm_timer_inject_irq_work(struct work_struct *work)
  89 {
  90         struct kvm_vcpu *vcpu;
  91
  92         vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
  93         vcpu->arch.timer_cpu.armed = false;
  94         kvm_timer_inject_irq(vcpu);
  95 }
  96
  97 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
  98 {
  99         struct arch_timer_cpu *timer;
 100         timer = container_of(hrt, struct arch_timer_cpu, timer);
 101         queue_work(wqueue, &timer->expired);
 102         return HRTIMER_NORESTART;
 103 }
 104
 105 /**
 106  * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
 107  * @vcpu: The vcpu pointer
 108  *
 109  * Disarm any pending soft timers, since the world-switch code will write the
 110  * virtual timer state back to the physical CPU.
 111  */
 112 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 113 {
 114         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 115
 116         /*
 117          * We're about to run this vcpu again, so there is no need to
 118          * keep the background timer running, as we're about to
 119          * populate the CPU timer again.
 120          */
 121         timer_disarm(timer);
 122 }
 123
 124 /**
 125  * kvm_timer_sync_hwstate - sync timer state from cpu
 126  * @vcpu: The vcpu pointer
 127  *
 128  * Check if the virtual timer was armed and either schedule a corresponding
 129  * soft timer or inject directly if already expired.
 130  */
 131 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 132 {
 133         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 134         cycle_t cval, now;
 135         u64 ns;
 136
 137         if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) ||
 138                 !(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE))
 139                 return;
 140
 141         cval = timer->cntv_cval;
 142         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 143
 144         BUG_ON(timer_is_armed(timer));
 145
 146         if (cval <= now) {
 147                 /*
 148                  * Timer has already expired while we were not
 149                  * looking. Inject the interrupt and carry on.
 150                  */
 151                 kvm_timer_inject_irq(vcpu);
 152                 return;
 153         }
 154
 155         ns = cyclecounter_cyc2ns(timecounter->cc, cval - now);
 156         timer_arm(timer, ns);
 157 }
 158
 159 void kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 160                           const struct kvm_irq_level *irq)
 161 {
 162         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 163
 164         /*
 165          * The vcpu timer irq number cannot be determined in
 166          * kvm_timer_vcpu_init() because it is called much before
 167          * kvm_vcpu_set_target(). To handle this, we determine
 168          * vcpu timer irq number when the vcpu is reset.
 169          */
 170         timer->irq = irq;
 171 }
 172
 173 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 174 {
 175         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 176
 177         INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
 178         hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 179         timer->timer.function = kvm_timer_expire;
 180 }
 181
 182 static void kvm_timer_init_interrupt(void *info)
 183 {
 184         enable_percpu_irq(host_vtimer_irq, 0);
 185 }
 186
 187
 188 static int kvm_timer_cpu_notify(struct notifier_block *self,
 189                                 unsigned long action, void *cpu)
 190 {
 191         switch (action) {
 192         case CPU_STARTING:
 193         case CPU_STARTING_FROZEN:
 194                 kvm_timer_init_interrupt(NULL);
 195                 break;
 196         case CPU_DYING:
 197         case CPU_DYING_FROZEN:
 198                 disable_percpu_irq(host_vtimer_irq);
 199                 break;
 200         }
 201
 202         return NOTIFY_OK;
 203 }
 204
 205 static struct notifier_block kvm_timer_cpu_nb = {
 206         .notifier_call = kvm_timer_cpu_notify,
 207 };
 208
 209 static const struct of_device_id arch_timer_of_match[] = {
 210         { .compatible   = "arm,armv7-timer",    },
 211         { .compatible   = "arm,armv8-timer",    },
 212         {},
 213 };
 214
 215 int kvm_timer_hyp_init(void)
 216 {
 217         struct device_node *np;
 218         unsigned int ppi;
 219         int err;
 220
 221         timecounter = arch_timer_get_timecounter();
 222         if (!timecounter)
 223                 return -ENODEV;
 224
 225         np = of_find_matching_node(NULL, arch_timer_of_match);
 226         if (!np) {
 227                 kvm_err("kvm_arch_timer: can't find DT node\n");
 228                 return -ENODEV;
 229         }
 230
 231         ppi = irq_of_parse_and_map(np, 2);
 232         if (!ppi) {
 233                 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
 234                 err = -EINVAL;
 235                 goto out;
 236         }
 237
 238         err = request_percpu_irq(ppi, kvm_arch_timer_handler,
 239                                  "kvm guest timer", kvm_get_running_vcpus());
 240         if (err) {
 241                 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
 242                         ppi, err);
 243                 goto out;
 244         }
 245
 246         host_vtimer_irq = ppi;
 247
 248         err = register_cpu_notifier(&kvm_timer_cpu_nb);
 249         if (err) {
 250                 kvm_err("Cannot register timer CPU notifier\n");
 251                 goto out_free;
 252         }
 253
 254         wqueue = create_singlethread_workqueue("kvm_arch_timer");
 255         if (!wqueue) {
 256                 err = -ENOMEM;
 257                 goto out_free;
 258         }
 259
 260         kvm_info("%s IRQ%d\n", np->name, ppi);
 261         on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 262
 263         goto out;
 264 out_free:
 265         free_percpu_irq(ppi, kvm_get_running_vcpus());
 266 out:
 267         of_node_put(np);
 268         return err;
 269 }
 270
 271 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 272 {
 273         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 274
 275         timer_disarm(timer);
 276 }
 277
 278 void kvm_timer_enable(struct kvm *kvm)
 279 {
 280         if (kvm->arch.timer.enabled)
 281                 return;
 282
 283         /*
 284          * There is a potential race here between VCPUs starting for the first
 285          * time, which may be enabling the timer multiple times.  That doesn't
 286          * hurt though, because we're just setting a variable to the same
 287          * variable that it already was.  The important thing is that all
 288          * VCPUs have the enabled variable set, before entering the guest, if
 289          * the arch timers are enabled.
 290          */
 291         if (timecounter && wqueue)
 292                 kvm->arch.timer.enabled = 1;
 293 }
 294
 295 void kvm_timer_init(struct kvm *kvm)
 296 {
 297         kvm->arch.timer.cntvoff = kvm_phys_timer_read();
 298 }