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

Steven Price
2023-01-27T11:32:39Z

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@arm.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