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
kvm_phys_timer_read(void)35 static cycle_t kvm_phys_timer_read(void)
36 {
37 return timecounter->cc->read(timecounter->cc);
38 }
39
timer_is_armed(struct arch_timer_cpu * timer)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 */
timer_arm(struct arch_timer_cpu * timer,u64 ns)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
timer_disarm(struct arch_timer_cpu * timer)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
kvm_timer_inject_irq(struct kvm_vcpu * vcpu)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
kvm_arch_timer_handler(int irq,void * dev_id)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 */
kvm_timer_inject_irq_work(struct work_struct * work)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
kvm_timer_expire(struct hrtimer * hrt)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
kvm_timer_should_fire(struct kvm_vcpu * vcpu)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 */
kvm_timer_flush_hwstate(struct kvm_vcpu * vcpu)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 */
kvm_timer_sync_hwstate(struct kvm_vcpu * vcpu)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
kvm_timer_vcpu_reset(struct kvm_vcpu * vcpu,const struct kvm_irq_level * irq)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
kvm_timer_vcpu_init(struct kvm_vcpu * vcpu)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
kvm_timer_init_interrupt(void * info)210 static void kvm_timer_init_interrupt(void *info)
211 {
212 enable_percpu_irq(host_vtimer_irq, 0);
213 }
214
kvm_arm_timer_set_reg(struct kvm_vcpu * vcpu,u64 regid,u64 value)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
kvm_arm_timer_get_reg(struct kvm_vcpu * vcpu,u64 regid)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
kvm_timer_cpu_notify(struct notifier_block * self,unsigned long action,void * cpu)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
kvm_timer_hyp_init(void)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
kvm_timer_vcpu_terminate(struct kvm_vcpu * vcpu)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
kvm_timer_enable(struct kvm * kvm)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
kvm_timer_init(struct kvm * kvm)357 void kvm_timer_init(struct kvm *kvm)
358 {
359 kvm->arch.timer.cntvoff = kvm_phys_timer_read();
360 }
361