linux-kernel - [RFC PATCH 12/28] KVM: arm64: Support timers in realm RECs

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Message-Id: <20230127112932.38045-13-steven.price@arm.com>
Date:   Fri, 27 Jan 2023 11:29:16 +0000
From:   Steven Price <steven.price@....com>
To:     kvm@...r.kernel.org, kvmarm@...ts.linux.dev
Cc:     Steven Price <steven.price@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
        James Morse <james.morse@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Joey Gouly <joey.gouly@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev
Subject: [RFC PATCH 12/28] KVM: arm64: Support timers in realm RECs

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.

Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/kvm/arch_timer.c  | 53 ++++++++++++++++++++++++++++++++----
 include/kvm/arm_arch_timer.h |  2 ++
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
index bb24a76b4224..d4af9ee58550 100644
--- a/arch/arm64/kvm/arch_timer.c
+++ b/arch/arm64/kvm/arch_timer.c
@@ -130,6 +130,11 @@ static void timer_set_offset(struct arch_timer_context *ctxt, u64 offset)
 {
 	struct kvm_vcpu *vcpu = ctxt->vcpu;
 
+	if (kvm_is_realm(vcpu->kvm)) {
+		WARN_ON(offset);
+		return;
+	}
+
 	switch(arch_timer_ctx_index(ctxt)) {
 	case TIMER_VTIMER:
 		__vcpu_sys_reg(vcpu, CNTVOFF_EL2) = offset;
@@ -411,6 +416,21 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
 	}
 }
 
+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_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_irq_can_fire(timer) && status;
+
+		if (level != timer->irq.level)
+			kvm_timer_update_irq(vcpu, level, timer);
+	}
+}
+
 /* Only called for a fully emulated timer */
 static void timer_emulate(struct arch_timer_context *ctx)
 {
@@ -621,6 +641,11 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
 	if (unlikely(!timer->enabled))
 		return;
 
+	kvm_timer_unblocking(vcpu);
+
+	if (vcpu_is_rec(vcpu))
+		return;
+
 	get_timer_map(vcpu, &map);
 
 	if (static_branch_likely(&has_gic_active_state)) {
@@ -633,8 +658,6 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
 
 	set_cntvoff(timer_get_offset(map.direct_vtimer));
 
-	kvm_timer_unblocking(vcpu);
-
 	timer_restore_state(map.direct_vtimer);
 	if (map.direct_ptimer)
 		timer_restore_state(map.direct_ptimer);
@@ -668,6 +691,9 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
 	if (unlikely(!timer->enabled))
 		return;
 
+	if (vcpu_is_rec(vcpu))
+		goto out;
+
 	get_timer_map(vcpu, &map);
 
 	timer_save_state(map.direct_vtimer);
@@ -686,9 +712,6 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
 	if (map.emul_ptimer)
 		soft_timer_cancel(&map.emul_ptimer->hrtimer);
 
-	if (kvm_vcpu_is_blocking(vcpu))
-		kvm_timer_blocking(vcpu);
-
 	/*
 	 * The kernel may decide to run userspace after calling vcpu_put, so
 	 * we reset cntvoff to 0 to ensure a consistent read between user
@@ -697,6 +720,11 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
 	 * virtual offset of zero, so no need to zero CNTVOFF_EL2 register.
 	 */
 	set_cntvoff(0);
+
+out:
+	if (kvm_vcpu_is_blocking(vcpu))
+		kvm_timer_blocking(vcpu);
+
 }
 
 /*
@@ -785,12 +813,18 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
 	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
 	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
 	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+	u64 cntvoff;
 
 	vtimer->vcpu = vcpu;
 	ptimer->vcpu = vcpu;
 
+	if (kvm_is_realm(vcpu->kvm))
+		cntvoff = 0;
+	else
+		cntvoff = kvm_phys_timer_read();
+
 	/* Synchronize cntvoff across all vtimers of a VM. */
-	update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
+	update_vtimer_cntvoff(vcpu, cntvoff);
 	timer_set_offset(ptimer, 0);
 
 	hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
@@ -1265,6 +1299,13 @@ 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);
 
 	ret = kvm_vgic_map_phys_irq(vcpu,
diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index cd6d8f260eab..158280e15a33 100644
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -76,6 +76,8 @@ 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);
-- 
2.34.1