Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 966 insertions, 0 deletions

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
new file mode 100644
index 000000000..17cecc96f
--- /dev/null
+++ b/virt/kvm/arm/arch_timer.c
@@ -0,0 +1,966 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/cpu.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/uaccess.h>
+
+#include <clocksource/arm_arch_timer.h>
+#include <asm/arch_timer.h>
+#include <asm/kvm_hyp.h>
+
+#include <kvm/arm_vgic.h>
+#include <kvm/arm_arch_timer.h>
+
+#include "trace.h"
+
+static struct timecounter *timecounter;
+static unsigned int host_vtimer_irq;
+static u32 host_vtimer_irq_flags;
+
+static DEFINE_STATIC_KEY_FALSE(has_gic_active_state);
+
+static const struct kvm_irq_level default_ptimer_irq = {
+	.irq	= 30,
+	.level	= 1,
+};
+
+static const struct kvm_irq_level default_vtimer_irq = {
+	.irq	= 27,
+	.level	= 1,
+};
+
+static bool kvm_timer_irq_can_fire(struct arch_timer_context *timer_ctx);
+static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
+				 struct arch_timer_context *timer_ctx);
+static bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx);
+
+u64 kvm_phys_timer_read(void)
+{
+	return timecounter->cc->read(timecounter->cc);
+}
+
+static inline bool userspace_irqchip(struct kvm *kvm)
+{
+	return static_branch_unlikely(&userspace_irqchip_in_use) &&
+		unlikely(!irqchip_in_kernel(kvm));
+}
+
+static void soft_timer_start(struct hrtimer *hrt, u64 ns)
+{
+	hrtimer_start(hrt, ktime_add_ns(ktime_get(), ns),
+		      HRTIMER_MODE_ABS);
+}
+
+static void soft_timer_cancel(struct hrtimer *hrt, struct work_struct *work)
+{
+	hrtimer_cancel(hrt);
+	if (work)
+		cancel_work_sync(work);
+}
+
+static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
+{
+	struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
+	struct arch_timer_context *vtimer;
+
+	/*
+	 * We may see a timer interrupt after vcpu_put() has been called which
+	 * sets the CPU's vcpu pointer to NULL, because even though the timer
+	 * has been disabled in vtimer_save_state(), the hardware interrupt
+	 * signal may not have been retired from the interrupt controller yet.
+	 */
+	if (!vcpu)
+		return IRQ_HANDLED;
+
+	vtimer = vcpu_vtimer(vcpu);
+	if (kvm_timer_should_fire(vtimer))
+		kvm_timer_update_irq(vcpu, true, vtimer);
+
+	if (userspace_irqchip(vcpu->kvm) &&
+	    !static_branch_unlikely(&has_gic_active_state))
+		disable_percpu_irq(host_vtimer_irq);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Work function for handling the backup timer that we schedule when a vcpu is
+ * no longer running, but had a timer programmed to fire in the future.
+ */
+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);
+
+	/*
+	 * If the vcpu is blocked we want to wake it up so that it will see
+	 * the timer has expired when entering the guest.
+	 */
+	kvm_vcpu_wake_up(vcpu);
+}
+
+static u64 kvm_timer_compute_delta(struct arch_timer_context *timer_ctx)
+{
+	u64 cval, now;
+
+	cval = timer_ctx->cnt_cval;
+	now = kvm_phys_timer_read() - timer_ctx->cntvoff;
+
+	if (now < cval) {
+		u64 ns;
+
+		ns = cyclecounter_cyc2ns(timecounter->cc,
+					 cval - now,
+					 timecounter->mask,
+					 &timecounter->frac);
+		return ns;
+	}
+
+	return 0;
+}
+
+static bool kvm_timer_irq_can_fire(struct arch_timer_context *timer_ctx)
+{
+	return !(timer_ctx->cnt_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
+		(timer_ctx->cnt_ctl & ARCH_TIMER_CTRL_ENABLE);
+}
+
+/*
+ * Returns the earliest expiration time in ns among guest timers.
+ * Note that it will return 0 if none of timers can fire.
+ */
+static u64 kvm_timer_earliest_exp(struct kvm_vcpu *vcpu)
+{
+	u64 min_virt = ULLONG_MAX, min_phys = ULLONG_MAX;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	if (kvm_timer_irq_can_fire(vtimer))
+		min_virt = kvm_timer_compute_delta(vtimer);
+
+	if (kvm_timer_irq_can_fire(ptimer))
+		min_phys = kvm_timer_compute_delta(ptimer);
+
+	/* If none of timers can fire, then return 0 */
+	if ((min_virt == ULLONG_MAX) && (min_phys == ULLONG_MAX))
+		return 0;
+
+	return min(min_virt, min_phys);
+}
+
+static enum hrtimer_restart kvm_bg_timer_expire(struct hrtimer *hrt)
+{
+	struct arch_timer_cpu *timer;
+	struct kvm_vcpu *vcpu;
+	u64 ns;
+
+	timer = container_of(hrt, struct arch_timer_cpu, bg_timer);
+	vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
+
+	/*
+	 * Check that the timer has really expired from the guest's
+	 * PoV (NTP on the host may have forced it to expire
+	 * early). If we should have slept longer, restart it.
+	 */
+	ns = kvm_timer_earliest_exp(vcpu);
+	if (unlikely(ns)) {
+		hrtimer_forward_now(hrt, ns_to_ktime(ns));
+		return HRTIMER_RESTART;
+	}
+
+	schedule_work(&timer->expired);
+	return HRTIMER_NORESTART;
+}
+
+static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt)
+{
+	struct arch_timer_context *ptimer;
+	struct arch_timer_cpu *timer;
+	struct kvm_vcpu *vcpu;
+	u64 ns;
+
+	timer = container_of(hrt, struct arch_timer_cpu, phys_timer);
+	vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
+	ptimer = vcpu_ptimer(vcpu);
+
+	/*
+	 * Check that the timer has really expired from the guest's
+	 * PoV (NTP on the host may have forced it to expire
+	 * early). If not ready, schedule for a later time.
+	 */
+	ns = kvm_timer_compute_delta(ptimer);
+	if (unlikely(ns)) {
+		hrtimer_forward_now(hrt, ns_to_ktime(ns));
+		return HRTIMER_RESTART;
+	}
+
+	kvm_timer_update_irq(vcpu, true, ptimer);
+	return HRTIMER_NORESTART;
+}
+
+static bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx)
+{
+	u64 cval, now;
+
+	if (timer_ctx->loaded) {
+		u32 cnt_ctl;
+
+		/* Only the virtual timer can be loaded so far */
+		cnt_ctl = read_sysreg_el0(cntv_ctl);
+		return  (cnt_ctl & ARCH_TIMER_CTRL_ENABLE) &&
+		        (cnt_ctl & ARCH_TIMER_CTRL_IT_STAT) &&
+		       !(cnt_ctl & ARCH_TIMER_CTRL_IT_MASK);
+	}
+
+	if (!kvm_timer_irq_can_fire(timer_ctx))
+		return false;
+
+	cval = timer_ctx->cnt_cval;
+	now = kvm_phys_timer_read() - timer_ctx->cntvoff;
+
+	return cval <= now;
+}
+
+bool kvm_timer_is_pending(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	if (kvm_timer_should_fire(vtimer))
+		return true;
+
+	return kvm_timer_should_fire(ptimer);
+}
+
+/*
+ * Reflect the timer output level into the kvm_run structure
+ */
+void kvm_timer_update_run(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+	struct kvm_sync_regs *regs = &vcpu->run->s.regs;
+
+	/* Populate the device bitmap with the timer states */
+	regs->device_irq_level &= ~(KVM_ARM_DEV_EL1_VTIMER |
+				    KVM_ARM_DEV_EL1_PTIMER);
+	if (kvm_timer_should_fire(vtimer))
+		regs->device_irq_level |= KVM_ARM_DEV_EL1_VTIMER;
+	if (kvm_timer_should_fire(ptimer))
+		regs->device_irq_level |= KVM_ARM_DEV_EL1_PTIMER;
+}
+
+static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
+				 struct arch_timer_context *timer_ctx)
+{
+	int ret;
+
+	timer_ctx->irq.level = new_level;
+	trace_kvm_timer_update_irq(vcpu->vcpu_id, timer_ctx->irq.irq,
+				   timer_ctx->irq.level);
+
+	if (!userspace_irqchip(vcpu->kvm)) {
+		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+					  timer_ctx->irq.irq,
+					  timer_ctx->irq.level,
+					  timer_ctx);
+		WARN_ON(ret);
+	}
+}
+
+/* Schedule the background timer for the emulated timer. */
+static void phys_timer_emulate(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	/*
+	 * If the timer can fire now, we don't need to have a soft timer
+	 * scheduled for the future.  If the timer cannot fire at all,
+	 * then we also don't need a soft timer.
+	 */
+	if (kvm_timer_should_fire(ptimer) || !kvm_timer_irq_can_fire(ptimer)) {
+		soft_timer_cancel(&timer->phys_timer, NULL);
+		return;
+	}
+
+	soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(ptimer));
+}
+
+/*
+ * Check if there was a change in the timer state, so that we should either
+ * raise or lower the line level to the GIC or schedule a background timer to
+ * emulate the physical timer.
+ */
+static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+	bool level;
+
+	if (unlikely(!timer->enabled))
+		return;
+
+	/*
+	 * The vtimer virtual interrupt is a 'mapped' interrupt, meaning part
+	 * of its lifecycle is offloaded to the hardware, and we therefore may
+	 * not have lowered the irq.level value before having to signal a new
+	 * interrupt, but have to signal an interrupt every time the level is
+	 * asserted.
+	 */
+	level = kvm_timer_should_fire(vtimer);
+	kvm_timer_update_irq(vcpu, level, vtimer);
+
+	phys_timer_emulate(vcpu);
+
+	if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
+		kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);
+}
+
+static void vtimer_save_state(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (!vtimer->loaded)
+		goto out;
+
+	if (timer->enabled) {
+		vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl);
+		vtimer->cnt_cval = read_sysreg_el0(cntv_cval);
+	}
+
+	/* Disable the virtual timer */
+	write_sysreg_el0(0, cntv_ctl);
+	isb();
+
+	vtimer->loaded = false;
+out:
+	local_irq_restore(flags);
+}
+
+/*
+ * Schedule the background timer before calling kvm_vcpu_block, so that this
+ * thread is removed from its waitqueue and made runnable when there's a timer
+ * interrupt to handle.
+ */
+void kvm_timer_schedule(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	vtimer_save_state(vcpu);
+
+	/*
+	 * No need to schedule a background timer if any guest timer has
+	 * already expired, because kvm_vcpu_block will return before putting
+	 * the thread to sleep.
+	 */
+	if (kvm_timer_should_fire(vtimer) || kvm_timer_should_fire(ptimer))
+		return;
+
+	/*
+	 * If both timers are not capable of raising interrupts (disabled or
+	 * masked), then there's no more work for us to do.
+	 */
+	if (!kvm_timer_irq_can_fire(vtimer) && !kvm_timer_irq_can_fire(ptimer))
+		return;
+
+	/*
+	 * The guest timers have not yet expired, schedule a background timer.
+	 * Set the earliest expiration time among the guest timers.
+	 */
+	soft_timer_start(&timer->bg_timer, kvm_timer_earliest_exp(vcpu));
+}
+
+static void vtimer_restore_state(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (vtimer->loaded)
+		goto out;
+
+	if (timer->enabled) {
+		write_sysreg_el0(vtimer->cnt_cval, cntv_cval);
+		isb();
+		write_sysreg_el0(vtimer->cnt_ctl, cntv_ctl);
+	}
+
+	vtimer->loaded = true;
+out:
+	local_irq_restore(flags);
+}
+
+void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	vtimer_restore_state(vcpu);
+
+	soft_timer_cancel(&timer->bg_timer, &timer->expired);
+}
+
+static void set_cntvoff(u64 cntvoff)
+{
+	u32 low = lower_32_bits(cntvoff);
+	u32 high = upper_32_bits(cntvoff);
+
+	/*
+	 * Since kvm_call_hyp doesn't fully support the ARM PCS especially on
+	 * 32-bit systems, but rather passes register by register shifted one
+	 * place (we put the function address in r0/x0), we cannot simply pass
+	 * a 64-bit value as an argument, but have to split the value in two
+	 * 32-bit halves.
+	 */
+	kvm_call_hyp(__kvm_timer_set_cntvoff, low, high);
+}
+
+static inline void set_vtimer_irq_phys_active(struct kvm_vcpu *vcpu, bool active)
+{
+	int r;
+	r = irq_set_irqchip_state(host_vtimer_irq, IRQCHIP_STATE_ACTIVE, active);
+	WARN_ON(r);
+}
+
+static void kvm_timer_vcpu_load_gic(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	bool phys_active;
+
+	if (irqchip_in_kernel(vcpu->kvm))
+		phys_active = kvm_vgic_map_is_active(vcpu, vtimer->irq.irq);
+	else
+		phys_active = vtimer->irq.level;
+	set_vtimer_irq_phys_active(vcpu, phys_active);
+}
+
+static void kvm_timer_vcpu_load_nogic(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+
+	/*
+	 * When using a userspace irqchip with the architected timers and a
+	 * host interrupt controller that doesn't support an active state, we
+	 * must still prevent continuously exiting from the guest, and
+	 * therefore mask the physical interrupt by disabling it on the host
+	 * interrupt controller when the virtual level is high, such that the
+	 * guest can make forward progress.  Once we detect the output level
+	 * being de-asserted, we unmask the interrupt again so that we exit
+	 * from the guest when the timer fires.
+	 */
+	if (vtimer->irq.level)
+		disable_percpu_irq(host_vtimer_irq);
+	else
+		enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
+}
+
+void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	if (unlikely(!timer->enabled))
+		return;
+
+	if (static_branch_likely(&has_gic_active_state))
+		kvm_timer_vcpu_load_gic(vcpu);
+	else
+		kvm_timer_vcpu_load_nogic(vcpu);
+
+	set_cntvoff(vtimer->cntvoff);
+
+	vtimer_restore_state(vcpu);
+
+	/* Set the background timer for the physical timer emulation. */
+	phys_timer_emulate(vcpu);
+
+	/* If the timer fired while we weren't running, inject it now */
+	if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
+		kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);
+}
+
+bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+	struct kvm_sync_regs *sregs = &vcpu->run->s.regs;
+	bool vlevel, plevel;
+
+	if (likely(irqchip_in_kernel(vcpu->kvm)))
+		return false;
+
+	vlevel = sregs->device_irq_level & KVM_ARM_DEV_EL1_VTIMER;
+	plevel = sregs->device_irq_level & KVM_ARM_DEV_EL1_PTIMER;
+
+	return kvm_timer_should_fire(vtimer) != vlevel ||
+	       kvm_timer_should_fire(ptimer) != plevel;
+}
+
+void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	if (unlikely(!timer->enabled))
+		return;
+
+	vtimer_save_state(vcpu);
+
+	/*
+	 * Cancel the physical timer emulation, because the only case where we
+	 * need it after a vcpu_put is in the context of a sleeping VCPU, and
+	 * in that case we already factor in the deadline for the physical
+	 * timer when scheduling the bg_timer.
+	 *
+	 * In any case, we re-schedule the hrtimer for the physical timer when
+	 * coming back to the VCPU thread in kvm_timer_vcpu_load().
+	 */
+	soft_timer_cancel(&timer->phys_timer, NULL);
+
+	/*
+	 * The kernel may decide to run userspace after calling vcpu_put, so
+	 * we reset cntvoff to 0 to ensure a consistent read between user
+	 * accesses to the virtual counter and kernel access to the physical
+	 * counter of non-VHE case. For VHE, the virtual counter uses a fixed
+	 * virtual offset of zero, so no need to zero CNTVOFF_EL2 register.
+	 */
+	if (!has_vhe())
+		set_cntvoff(0);
+}
+
+/*
+ * With a userspace irqchip we have to check if the guest de-asserted the
+ * timer and if so, unmask the timer irq signal on the host interrupt
+ * controller to ensure that we see future timer signals.
+ */
+static void unmask_vtimer_irq_user(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+
+	if (!kvm_timer_should_fire(vtimer)) {
+		kvm_timer_update_irq(vcpu, false, vtimer);
+		if (static_branch_likely(&has_gic_active_state))
+			set_vtimer_irq_phys_active(vcpu, false);
+		else
+			enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
+	}
+}
+
+void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	if (unlikely(!timer->enabled))
+		return;
+
+	if (unlikely(!irqchip_in_kernel(vcpu->kvm)))
+		unmask_vtimer_irq_user(vcpu);
+}
+
+int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	/*
+	 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
+	 * and to 0 for ARMv7.  We provide an implementation that always
+	 * resets the timer to be disabled and unmasked and is compliant with
+	 * the ARMv7 architecture.
+	 */
+	vtimer->cnt_ctl = 0;
+	ptimer->cnt_ctl = 0;
+	kvm_timer_update_state(vcpu);
+
+	if (timer->enabled && irqchip_in_kernel(vcpu->kvm))
+		kvm_vgic_reset_mapped_irq(vcpu, vtimer->irq.irq);
+
+	return 0;
+}
+
+/* Make the updates of cntvoff for all vtimer contexts atomic */
+static void update_vtimer_cntvoff(struct kvm_vcpu *vcpu, u64 cntvoff)
+{
+	int i;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_vcpu *tmp;
+
+	mutex_lock(&kvm->lock);
+	kvm_for_each_vcpu(i, tmp, kvm)
+		vcpu_vtimer(tmp)->cntvoff = cntvoff;
+
+	/*
+	 * When called from the vcpu create path, the CPU being created is not
+	 * included in the loop above, so we just set it here as well.
+	 */
+	vcpu_vtimer(vcpu)->cntvoff = cntvoff;
+	mutex_unlock(&kvm->lock);
+}
+
+void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	/* Synchronize cntvoff across all vtimers of a VM. */
+	update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
+	vcpu_ptimer(vcpu)->cntvoff = 0;
+
+	INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
+	hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	timer->bg_timer.function = kvm_bg_timer_expire;
+
+	hrtimer_init(&timer->phys_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	timer->phys_timer.function = kvm_phys_timer_expire;
+
+	vtimer->irq.irq = default_vtimer_irq.irq;
+	ptimer->irq.irq = default_ptimer_irq.irq;
+}
+
+static void kvm_timer_init_interrupt(void *info)
+{
+	enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
+}
+
+int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
+{
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+	switch (regid) {
+	case KVM_REG_ARM_TIMER_CTL:
+		vtimer->cnt_ctl = value & ~ARCH_TIMER_CTRL_IT_STAT;
+		break;
+	case KVM_REG_ARM_TIMER_CNT:
+		update_vtimer_cntvoff(vcpu, kvm_phys_timer_read() - value);
+		break;
+	case KVM_REG_ARM_TIMER_CVAL:
+		vtimer->cnt_cval = value;
+		break;
+	case KVM_REG_ARM_PTIMER_CTL:
+		ptimer->cnt_ctl = value & ~ARCH_TIMER_CTRL_IT_STAT;
+		break;
+	case KVM_REG_ARM_PTIMER_CVAL:
+		ptimer->cnt_cval = value;
+		break;
+
+	default:
+		return -1;
+	}
+
+	kvm_timer_update_state(vcpu);
+	return 0;
+}
+
+static u64 read_timer_ctl(struct arch_timer_context *timer)
+{
+	/*
+	 * Set ISTATUS bit if it's expired.
+	 * Note that according to ARMv8 ARM Issue A.k, ISTATUS bit is
+	 * UNKNOWN when ENABLE bit is 0, so we chose to set ISTATUS bit
+	 * regardless of ENABLE bit for our implementation convenience.
+	 */
+	if (!kvm_timer_compute_delta(timer))
+		return timer->cnt_ctl | ARCH_TIMER_CTRL_IT_STAT;
+	else
+		return timer->cnt_ctl;
+}
+
+u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
+{
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+
+	switch (regid) {
+	case KVM_REG_ARM_TIMER_CTL:
+		return read_timer_ctl(vtimer);
+	case KVM_REG_ARM_TIMER_CNT:
+		return kvm_phys_timer_read() - vtimer->cntvoff;
+	case KVM_REG_ARM_TIMER_CVAL:
+		return vtimer->cnt_cval;
+	case KVM_REG_ARM_PTIMER_CTL:
+		return read_timer_ctl(ptimer);
+	case KVM_REG_ARM_PTIMER_CVAL:
+		return ptimer->cnt_cval;
+	case KVM_REG_ARM_PTIMER_CNT:
+		return kvm_phys_timer_read();
+	}
+	return (u64)-1;
+}
+
+static int kvm_timer_starting_cpu(unsigned int cpu)
+{
+	kvm_timer_init_interrupt(NULL);
+	return 0;
+}
+
+static int kvm_timer_dying_cpu(unsigned int cpu)
+{
+	disable_percpu_irq(host_vtimer_irq);
+	return 0;
+}
+
+int kvm_timer_hyp_init(bool has_gic)
+{
+	struct arch_timer_kvm_info *info;
+	int err;
+
+	info = arch_timer_get_kvm_info();
+	timecounter = &info->timecounter;
+
+	if (!timecounter->cc) {
+		kvm_err("kvm_arch_timer: uninitialized timecounter\n");
+		return -ENODEV;
+	}
+
+	if (info->virtual_irq <= 0) {
+		kvm_err("kvm_arch_timer: invalid virtual timer IRQ: %d\n",
+			info->virtual_irq);
+		return -ENODEV;
+	}
+	host_vtimer_irq = info->virtual_irq;
+
+	host_vtimer_irq_flags = irq_get_trigger_type(host_vtimer_irq);
+	if (host_vtimer_irq_flags != IRQF_TRIGGER_HIGH &&
+	    host_vtimer_irq_flags != IRQF_TRIGGER_LOW) {
+		kvm_err("Invalid trigger for IRQ%d, assuming level low\n",
+			host_vtimer_irq);
+		host_vtimer_irq_flags = IRQF_TRIGGER_LOW;
+	}
+
+	err = request_percpu_irq(host_vtimer_irq, 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",
+			host_vtimer_irq, err);
+		return err;
+	}
+
+	if (has_gic) {
+		err = irq_set_vcpu_affinity(host_vtimer_irq,
+					    kvm_get_running_vcpus());
+		if (err) {
+			kvm_err("kvm_arch_timer: error setting vcpu affinity\n");
+			goto out_free_irq;
+		}
+
+		static_branch_enable(&has_gic_active_state);
+	}
+
+	kvm_debug("virtual timer IRQ%d\n", host_vtimer_irq);
+
+	cpuhp_setup_state(CPUHP_AP_KVM_ARM_TIMER_STARTING,
+			  "kvm/arm/timer:starting", kvm_timer_starting_cpu,
+			  kvm_timer_dying_cpu);
+	return 0;
+out_free_irq:
+	free_percpu_irq(host_vtimer_irq, kvm_get_running_vcpus());
+	return err;
+}
+
+void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+
+	soft_timer_cancel(&timer->bg_timer, &timer->expired);
+	soft_timer_cancel(&timer->phys_timer, NULL);
+	kvm_vgic_unmap_phys_irq(vcpu, vtimer->irq.irq);
+}
+
+static bool timer_irqs_are_valid(struct kvm_vcpu *vcpu)
+{
+	int vtimer_irq, ptimer_irq;
+	int i, ret;
+
+	vtimer_irq = vcpu_vtimer(vcpu)->irq.irq;
+	ret = kvm_vgic_set_owner(vcpu, vtimer_irq, vcpu_vtimer(vcpu));
+	if (ret)
+		return false;
+
+	ptimer_irq = vcpu_ptimer(vcpu)->irq.irq;
+	ret = kvm_vgic_set_owner(vcpu, ptimer_irq, vcpu_ptimer(vcpu));
+	if (ret)
+		return false;
+
+	kvm_for_each_vcpu(i, vcpu, vcpu->kvm) {
+		if (vcpu_vtimer(vcpu)->irq.irq != vtimer_irq ||
+		    vcpu_ptimer(vcpu)->irq.irq != ptimer_irq)
+			return false;
+	}
+
+	return true;
+}
+
+bool kvm_arch_timer_get_input_level(int vintid)
+{
+	struct kvm_vcpu *vcpu = kvm_arm_get_running_vcpu();
+	struct arch_timer_context *timer;
+
+	if (vintid == vcpu_vtimer(vcpu)->irq.irq)
+		timer = vcpu_vtimer(vcpu);
+	else
+		BUG(); /* We only map the vtimer so far */
+
+	return kvm_timer_should_fire(timer);
+}
+
+int kvm_timer_enable(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	int ret;
+
+	if (timer->enabled)
+		return 0;
+
+	/* Without a VGIC we do not map virtual IRQs to physical IRQs */
+	if (!irqchip_in_kernel(vcpu->kvm))
+		goto no_vgic;
+
+	if (!vgic_initialized(vcpu->kvm))
+		return -ENODEV;
+
+	if (!timer_irqs_are_valid(vcpu)) {
+		kvm_debug("incorrectly configured timer irqs\n");
+		return -EINVAL;
+	}
+
+	ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq,
+				    kvm_arch_timer_get_input_level);
+	if (ret)
+		return ret;
+
+no_vgic:
+	timer->enabled = 1;
+	return 0;
+}
+
+/*
+ * On VHE system, we only need to configure trap on physical timer and counter
+ * accesses in EL0 and EL1 once, not for every world switch.
+ * The host kernel runs at EL2 with HCR_EL2.TGE == 1,
+ * and this makes those bits have no effect for the host kernel execution.
+ */
+void kvm_timer_init_vhe(void)
+{
+	/* When HCR_EL2.E2H ==1, EL1PCEN and EL1PCTEN are shifted by 10 */
+	u32 cnthctl_shift = 10;
+	u64 val;
+
+	/*
+	 * Disallow physical timer access for the guest.
+	 * Physical counter access is allowed.
+	 */
+	val = read_sysreg(cnthctl_el2);
+	val &= ~(CNTHCTL_EL1PCEN << cnthctl_shift);
+	val |= (CNTHCTL_EL1PCTEN << cnthctl_shift);
+	write_sysreg(val, cnthctl_el2);
+}
+
+static void set_timer_irqs(struct kvm *kvm, int vtimer_irq, int ptimer_irq)
+{
+	struct kvm_vcpu *vcpu;
+	int i;
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		vcpu_vtimer(vcpu)->irq.irq = vtimer_irq;
+		vcpu_ptimer(vcpu)->irq.irq = ptimer_irq;
+	}
+}
+
+int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
+{
+	int __user *uaddr = (int __user *)(long)attr->addr;
+	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
+	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+	int irq;
+
+	if (!irqchip_in_kernel(vcpu->kvm))
+		return -EINVAL;
+
+	if (get_user(irq, uaddr))
+		return -EFAULT;
+
+	if (!(irq_is_ppi(irq)))
+		return -EINVAL;
+
+	if (vcpu->arch.timer_cpu.enabled)
+		return -EBUSY;
+
+	switch (attr->attr) {
+	case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
+		set_timer_irqs(vcpu->kvm, irq, ptimer->irq.irq);
+		break;
+	case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
+		set_timer_irqs(vcpu->kvm, vtimer->irq.irq, irq);
+		break;
+	default:
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
+{
+	int __user *uaddr = (int __user *)(long)attr->addr;
+	struct arch_timer_context *timer;
+	int irq;
+
+	switch (attr->attr) {
+	case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
+		timer = vcpu_vtimer(vcpu);
+		break;
+	case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
+		timer = vcpu_ptimer(vcpu);
+		break;
+	default:
+		return -ENXIO;
+	}
+
+	irq = timer->irq.irq;
+	return put_user(irq, uaddr);
+}
+
+int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
+{
+	switch (attr->attr) {
+	case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
+	case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
+		return 0;
+	}
+
+	return -ENXIO;
+}