Re: [PATCH v2 16/43] KVM: arm64: Support timers in realm RECs

Suzuki K Poulose
2024-04-18T09:30:42Z

On 12/04/2024 09:42, Steven Price wrote:
> 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.
>

minor nit: It may be worth mentioning this will be hooked in, when we
add the Realm exit handling.

Otherwise looks good to me.

Suzuki

> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> arch/arm64/kvm/arch_timer.c | 45 ++++++++++++++++++++++++++++++++----
> include/kvm/arm_arch_timer.h | 2 ++
> 2 files changed, 43 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
> index 879982b1cc73..0b2be34a9ba3 100644
> --- a/arch/arm64/kvm/arch_timer.c
> +++ b/arch/arm64/kvm/arch_timer.c
> @@ -162,6 +162,13 @@ static void timer_set_cval(struct arch_timer_context *ctxt, u64 cval)
>
> 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;
> + }
> +
> if (!ctxt->offset.vm_offset) {
> WARN(offset, "timer %ld\n", arch_timer_ctx_index(ctxt));
> return;
> @@ -460,6 +467,21 @@ 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_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_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)
> {
> @@ -831,6 +853,8 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
> if (unlikely(!timer->enabled))
> return;
>
> + kvm_timer_unblocking(vcpu);
> +
> get_timer_map(vcpu, &map);
>
> if (static_branch_likely(&has_gic_active_state)) {
> @@ -844,8 +868,6 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
> kvm_timer_vcpu_load_nogic(vcpu);
> }
>
> - kvm_timer_unblocking(vcpu);
> -
> timer_restore_state(map.direct_vtimer);
> if (map.direct_ptimer)
> timer_restore_state(map.direct_ptimer);
> @@ -988,7 +1010,9 @@ static void timer_context_init(struct kvm_vcpu *vcpu, int timerid)
>
> ctxt->vcpu = vcpu;
>
> - if (timerid == TIMER_VTIMER)
> + if (kvm_is_realm(vcpu->kvm))
> + ctxt->offset.vm_offset = NULL;
> + else if (timerid == TIMER_VTIMER)
> ctxt->offset.vm_offset = &kvm->arch.timer_data.voffset;
> else
> ctxt->offset.vm_offset = &kvm->arch.timer_data.poffset;
> @@ -1011,13 +1035,19 @@ static void timer_context_init(struct kvm_vcpu *vcpu, int timerid)
> void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
> {
> struct arch_timer_cpu *timer = vcpu_timer(vcpu);
> + u64 cntvoff;
>
> for (int i = 0; i < NR_KVM_TIMERS; i++)
> timer_context_init(vcpu, i);
>
> + if (kvm_is_realm(vcpu->kvm))
> + cntvoff = 0;
> + else
> + cntvoff = kvm_phys_timer_read();
> +
> /* Synchronize offsets across timers of a VM if not already provided */
> if (!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_vtimer(vcpu), cntvoff);
> timer_set_offset(vcpu_ptimer(vcpu), 0);
> }
>
> @@ -1525,6 +1555,13 @@ 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 c819c5d16613..d8ab297560d0 100644
> --- a/include/kvm/arm_arch_timer.h
> +++ b/include/kvm/arm_arch_timer.h
> @@ -112,6 +112,8 @@ 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);