[PATCH v15 13/37] KVM: arm64: CCA: Support timers in realm RECs

[Steven Price <steven.price@arm.com>]

The RMM keeps track of the timer while the realm REC is running, but on
exit to the normal world KVM is responsible for handling the timers.

A later patch adds the support for propagating the timer values from the
exit data structure and calling kvm_realm_timers_update().

Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes since v14:
 * Special case in kvm_timer_vcpu_load()/kvm_timer_vcpu_put() the timer
   handling.
Changes since v12:
 * Adapt to upstream changes.
Changes since v11:
 * Drop the kvm_is_realm() check from timer_set_offset(). We already
   ensure that the offset is 0 when calling the function.
Changes since v10:
 * KVM_CAP_COUNTER_OFFSET is now already hidden by a previous patch.
Changes since v9:
 * No need to move the call to kvm_timer_unblocking() in
   kvm_timer_vcpu_load().
Changes since v7:
 * Hide KVM_CAP_COUNTER_OFFSET for realm guests.
---
 arch/arm64/kvm/arch_timer.c  | 38 +++++++++++++++++++++++++++++++++---
 include/kvm/arm_arch_timer.h |  2 ++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
index 4155fe89b58a..fdd68f1f5b7b 100644
--- a/arch/arm64/kvm/arch_timer.c
+++ b/arch/arm64/kvm/arch_timer.c
@@ -482,6 +482,20 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
 			    timer_ctx);
 }
 
+void kvm_realm_timers_update(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *arch_timer = &vcpu->arch.timer_cpu;
+	int i;
+
+	for (i = 0; i < NR_KVM_EL0_TIMERS; i++) {
+		struct arch_timer_context *timer = &arch_timer->timers[i];
+		bool status = timer_get_ctl(timer) & ARCH_TIMER_CTRL_IT_STAT;
+		bool level = kvm_timer_enabled(timer) && status;
+
+		kvm_timer_update_irq(vcpu, level, timer);
+	}
+}
+
 /* Only called for a fully emulated timer */
 static void timer_emulate(struct arch_timer_context *ctx)
 {
@@ -888,6 +902,11 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
 	if (unlikely(!timer->enabled))
 		return;
 
+	if (vcpu_is_rec(vcpu)) {
+		kvm_timer_unblocking(vcpu);
+		return;
+	}
+
 	get_timer_map(vcpu, &map);
 
 	if (static_branch_likely(&has_gic_active_state)) {
@@ -923,6 +942,12 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
 	if (unlikely(!timer->enabled))
 		return;
 
+	if (vcpu_is_rec(vcpu)) {
+		if (kvm_vcpu_is_blocking(vcpu))
+			kvm_timer_blocking(vcpu);
+		return;
+	}
+
 	get_timer_map(vcpu, &map);
 
 	timer_save_state(map.direct_vtimer);
@@ -1073,7 +1098,7 @@ static void timer_context_init(struct kvm_vcpu *vcpu, int timerid)
 
 	ctxt->timer_id = timerid;
 
-	if (!kvm_vm_is_protected(vcpu->kvm)) {
+	if (!kvm_vm_is_protected(vcpu->kvm) && !vcpu_is_rec(vcpu)) {
 		if (timerid == TIMER_VTIMER)
 			ctxt->offset.vm_offset = &kvm->arch.timer_data.voffset;
 		else
@@ -1104,7 +1129,7 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 		timer_context_init(vcpu, i);
 
 	/* Synchronize offsets across timers of a VM if not already provided */
-	if (!vcpu_is_protected(vcpu) &&
+	if (!vcpu_is_protected(vcpu) && !vcpu_is_rec(vcpu) &&
 	    !test_bit(KVM_ARCH_FLAG_VM_COUNTER_OFFSET, &vcpu->kvm->arch.flags)) {
 		timer_set_offset(vcpu_vtimer(vcpu), kvm_phys_timer_read());
 		timer_set_offset(vcpu_ptimer(vcpu), 0);
@@ -1600,6 +1625,13 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 	}
 
+	/*
+	 * We don't use mapped IRQs for Realms because the RMI doesn't allow
+	 * us setting the LR.HW bit in the VGIC.
+	 */
+	if (vcpu_is_rec(vcpu))
+		return 0;
+
 	get_timer_map(vcpu, &map);
 
 	ops = vgic_is_v5(vcpu->kvm) ? &arch_timer_irq_ops_vgic_v5 :
@@ -1729,7 +1761,7 @@ int kvm_vm_ioctl_set_counter_offset(struct kvm *kvm,
 	if (offset->reserved)
 		return -EINVAL;
 
-	if (kvm_vm_is_protected(kvm))
+	if (kvm_vm_is_protected(kvm) || kvm_is_realm(kvm))
 		return -EINVAL;
 
 	mutex_lock(&kvm->lock);
diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index 15a4f97f8105..31e48d5dbc31 100644
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -108,6 +108,8 @@ int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
 int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
 int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
 
+void kvm_realm_timers_update(struct kvm_vcpu *vcpu);
+
 u64 kvm_phys_timer_read(void);
 
 void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu);
-- 
2.43.0