On Sat, Nov 10, 2012 at 03:46:19PM +0000, Christoffer Dall wrote:

Endianness?

 };

 struct arch_timer_cpu {
+#ifdef CONFIG_KVM_ARM_TIMER
+       /* Registers: control register, timer value */
+       u32                             cntv_ctl;       /* Saved/restored */
+       union {
+               cycle_t                 cntv_cval;
+               struct {
+                       u32             low;            /* Saved/restored */
+                       u32             high;           /* Saved/restored */
+               } cntv_cval32;
+       };

Similarly.

This should be parameterised by the vCPU type.

Maybe kvm/arch_timer.c since it seems to be specific to that device and
matches the naming for the main driver under kernel/? If we get new virtual
timer devices in the future, I guess this would need to be split up so the
arch-timer-specific bits are separate from generic hrtimer and kvm code.

This is ARCH_TIMER_CTRL_IT_MASK right? We should make that definition
available if it is needed here.

+       kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+                           vcpu->arch.timer_cpu.irq->irq,
+                           vcpu->arch.timer_cpu.irq->level);
+}
+
+static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
+{
+       struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
+
+       /*
+        * We disable the timer in the world switch and let it be
+        * handled by kvm_timer_sync_from_cpu(). Getting a timer
+        * interrupt at this point is a sure sign of some major
+        * breakage.
+        */
+       pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
+       return IRQ_HANDLED;

IRQ_NONE?

+}
+
+static void kvm_timer_inject_irq_work(struct work_struct *work)
+{
+       struct kvm_vcpu *vcpu;
+
+       vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
+       vcpu->arch.timer_cpu.armed = false;
+       kvm_timer_inject_irq(vcpu);
+}
+
+static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
+{
+       struct arch_timer_cpu *timer;
+       timer = container_of(hrt, struct arch_timer_cpu, timer);
+       queue_work(wqueue, &timer->expired);
+       return HRTIMER_NORESTART;
+}
+
+void kvm_timer_sync_to_cpu(struct kvm_vcpu *vcpu)
+{
+       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+       /*
+        * We're about to run this vcpu again, so there is no need to
+        * keep the background timer running, as we're about to
+        * populate the CPU timer again.
+        */
+       if (timer->armed) {
+               hrtimer_cancel(&timer->timer);
+               cancel_work_sync(&timer->expired);
+               timer->armed = false;
+       }
+}

I think some helper functions like timer_is_armed, timer_arm and
timer_disarm would make this more readable (resisting arm_timer, which
confuses things more!).

+
+void kvm_timer_sync_from_cpu(struct kvm_vcpu *vcpu)
+{
+       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+       cycle_t cval, now;
+       u64 ns;
+
+       /* Check if the timer is enabled and unmasked first */
+       if ((timer->cntv_ctl & 3) != 1)
+               return;

Again, we should create/use ARCH_TIMER #defines for this hardware bits.

+       cval = timer->cntv_cval;
+       now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;

We probably want to add an isb() *before* the mrrc in
arch_timer_counter_read if you want to do things like this, because the
counter can be speculated in advance.

+       BUG_ON(timer->armed);
+
+       if (cval <= now) {
+               /*
+                * Timer has already expired while we were not
+                * looking. Inject the interrupt and carry on.
+                */
+               kvm_timer_inject_irq(vcpu);
+               return;
+       }

Does this buy you much? You still have to cope with the timer expiring here
anyway.

+       timer->armed = true;
+       ns = cyclecounter_cyc2ns(timecounter->cc, cval - now);
+       hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
+                     HRTIMER_MODE_ABS);
+}
+
+void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
+{
+       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+       INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
+       hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+       timer->timer.function = kvm_timer_expire;
+}
+
+static void kvm_timer_init_interrupt(void *info)
+{
+       unsigned int *irqp = info;
+
+       enable_percpu_irq(*irqp, 0);

IRQ_TYPE_NONE

+}
+
+
+static const struct of_device_id arch_timer_of_match[] = {
+       { .compatible   = "arm,armv7-timer",    },
+       {},
+};
+
+int kvm_timer_hyp_init(void)
+{
+       struct device_node *np;
+       unsigned int ppi;
+       int err;
+
+       timecounter = arch_timer_get_timecounter();
+       if (!timecounter)
+               return -ENODEV;
+
+       np = of_find_matching_node(NULL, arch_timer_of_match);
+       if (!np) {
+               kvm_err("kvm_arch_timer: can't find DT node\n");
+               return -ENODEV;
+       }
+
+       ppi = irq_of_parse_and_map(np, 2);
+       if (!ppi) {
+               kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
+               return -EINVAL;
+       }
+
+       err = request_percpu_irq(ppi, kvm_arch_timer_handler,
+                                "kvm guest timer", kvm_get_running_vcpus());
+       if (err) {
+               kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
+                       ppi, err);
+               return err;
+       }
+
+       wqueue = create_singlethread_workqueue("kvm_arch_timer");
+       if (!wqueue) {
+               free_percpu_irq(ppi, kvm_get_running_vcpus());
+               return -ENOMEM;
+       }
+
+       kvm_info("%s IRQ%d\n", np->name, ppi);
+       on_each_cpu(kvm_timer_init_interrupt, &ppi, 1);

on_each_cpu currently just returns 0, but you could use that as your return
value for good measure anyway.

+       return 0;
+}
+
+void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
+{
+       struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+       hrtimer_cancel(&timer->timer);
+       cancel_work_sync(&timer->expired);
+}
+
+int kvm_timer_init(struct kvm *kvm)
+{
+       if (timecounter && wqueue) {
+               kvm->arch.timer.cntvoff = kvm_phys_timer_read();

Shouldn't this be initialised to 0 and then updated on world switch?

Will