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         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
  65
  66         timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
  67         kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
  68                             timer->irq->irq,
  69                             timer->irq->level);
  70 }
  71
  72 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
  73 {
  74         struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
  75
  76         /*
  77          * We disable the timer in the world switch and let it be
  78          * handled by kvm_timer_sync_hwstate(). Getting a timer
  79          * interrupt at this point is a sure sign of some major
  80          * breakage.
  81          */
  82         pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
  83         return IRQ_HANDLED;
  84 }
  85
  86 static void kvm_timer_inject_irq_work(struct work_struct *work)
  87 {
  88         struct kvm_vcpu *vcpu;
  89
  90         vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
  91         vcpu->arch.timer_cpu.armed = false;
  92         kvm_timer_inject_irq(vcpu);
  93 }
  94
  95 static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
  96 {
  97         struct arch_timer_cpu *timer;
  98         timer = container_of(hrt, struct arch_timer_cpu, timer);
  99         queue_work(wqueue, &timer->expired);
 100         return HRTIMER_NORESTART;
 101 }
 102
 103 /**
 104  * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
 105  * @vcpu: The vcpu pointer
 106  *
 107  * Disarm any pending soft timers, since the world-switch code will write the
 108  * virtual timer state back to the physical CPU.
 109  */
 110 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 111 {
 112         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 113
 114         /*
 115          * We're about to run this vcpu again, so there is no need to
 116          * keep the background timer running, as we're about to
 117          * populate the CPU timer again.
 118          */
 119         timer_disarm(timer);
 120 }
 121
 122 /**
 123  * kvm_timer_sync_hwstate - sync timer state from cpu
 124  * @vcpu: The vcpu pointer
 125  *
 126  * Check if the virtual timer was armed and either schedule a corresponding
 127  * soft timer or inject directly if already expired.
 128  */
 129 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 130 {
 131         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 132         cycle_t cval, now;
 133         u64 ns;
 134
 135         if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) ||
 136                 !(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE))
 137                 return;
 138
 139         cval = timer->cntv_cval;
 140         now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
 141
 142         BUG_ON(timer_is_armed(timer));
 143
 144         if (cval <= now) {
 145                 /*
 146                  * Timer has already expired while we were not
 147                  * looking. Inject the interrupt and carry on.
 148                  */
 149                 kvm_timer_inject_irq(vcpu);
 150                 return;
 151         }
 152
 153         ns = cyclecounter_cyc2ns(timecounter->cc, cval - now);
 154         timer_arm(timer, ns);
 155 }
 156
 157 void kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 158                           const struct kvm_irq_level *irq)
 159 {
 160         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 161
 162         /*
 163          * The vcpu timer irq number cannot be determined in
 164          * kvm_timer_vcpu_init() because it is called much before
 165          * kvm_vcpu_set_target(). To handle this, we determine
 166          * vcpu timer irq number when the vcpu is reset.
 167          */
 168         timer->irq = irq;
 169 }
 170
 171 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 172 {
 173         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 174
 175         INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
 176         hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 177         timer->timer.function = kvm_timer_expire;
 178 }
 179
 180 static void kvm_timer_init_interrupt(void *info)
 181 {
 182         enable_percpu_irq(host_vtimer_irq, 0);
 183 }
 184
 185
 186 static int kvm_timer_cpu_notify(struct notifier_block *self,
 187                                 unsigned long action, void *cpu)
 188 {
 189         switch (action) {
 190         case CPU_STARTING:
 191         case CPU_STARTING_FROZEN:
 192                 kvm_timer_init_interrupt(NULL);
 193                 break;
 194         case CPU_DYING:
 195         case CPU_DYING_FROZEN:
 196                 disable_percpu_irq(host_vtimer_irq);
 197                 break;
 198         }
 199
 200         return NOTIFY_OK;
 201 }
 202
 203 static struct notifier_block kvm_timer_cpu_nb = {
 204         .notifier_call = kvm_timer_cpu_notify,
 205 };
 206
 207 static const struct of_device_id arch_timer_of_match[] = {
 208         { .compatible   = "arm,armv7-timer",    },
 209         { .compatible   = "arm,armv8-timer",    },
 210         {},
 211 };
 212
 213 int kvm_timer_hyp_init(void)
 214 {
 215         struct device_node *np;
 216         unsigned int ppi;
 217         int err;
 218
 219         timecounter = arch_timer_get_timecounter();
 220         if (!timecounter)
 221                 return -ENODEV;
 222
 223         np = of_find_matching_node(NULL, arch_timer_of_match);
 224         if (!np) {
 225                 kvm_err("kvm_arch_timer: can't find DT node\n");
 226                 return -ENODEV;
 227         }
 228
 229         ppi = irq_of_parse_and_map(np, 2);
 230         if (!ppi) {
 231                 kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
 232                 err = -EINVAL;
 233                 goto out;
 234         }
 235
 236         err = request_percpu_irq(ppi, kvm_arch_timer_handler,
 237                                  "kvm guest timer", kvm_get_running_vcpus());
 238         if (err) {
 239                 kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
 240                         ppi, err);
 241                 goto out;
 242         }
 243
 244         host_vtimer_irq = ppi;
 245
 246         err = register_cpu_notifier(&kvm_timer_cpu_nb);
 247         if (err) {
 248                 kvm_err("Cannot register timer CPU notifier\n");
 249                 goto out_free;
 250         }
 251
 252         wqueue = create_singlethread_workqueue("kvm_arch_timer");
 253         if (!wqueue) {
 254                 err = -ENOMEM;
 255                 goto out_free;
 256         }
 257
 258         kvm_info("%s IRQ%d\n", np->name, ppi);
 259         on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 260
 261         goto out;
 262 out_free:
 263         free_percpu_irq(ppi, kvm_get_running_vcpus());
 264 out:
 265         of_node_put(np);
 266         return err;
 267 }
 268
 269 void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 270 {
 271         struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 272
 273         timer_disarm(timer);
 274 }
 275
 276 int kvm_timer_init(struct kvm *kvm)
 277 {
 278         if (timecounter && wqueue) {
 279                 kvm->arch.timer.cntvoff = kvm_phys_timer_read();
 280                 kvm->arch.timer.enabled = 1;
 281         }
 282
 283         return 0;
 284 }