[PATCH 01/10] arm/arm64: KVM: Fix ordering of timer/GIC on guest entry
Alex Bennée
alex.bennee at linaro.org
Tue Jun 9 04:29:35 PDT 2015
Marc Zyngier <marc.zyngier at arm.com> writes:
> As we now inject the timer interrupt when we're about to enter
> the guest, it makes a lot more sense to make sure this happens
> before the vgic code queues the pending interrupts.
>
> Otherwise, we get the interrupt on the following exit, which is
> not great for latency (and leads to all kind of bizarre issues
> when using with active interrupts at the HW level).
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
> arch/arm/kvm/arm.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index d9631ec..46db690 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -529,9 +529,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> if (vcpu->arch.pause)
> vcpu_pause(vcpu);
>
> - kvm_vgic_flush_hwstate(vcpu);
> kvm_timer_flush_hwstate(vcpu);
>
> + kvm_vgic_flush_hwstate(vcpu);
> +
> local_irq_disable();
>
> /*
> @@ -544,8 +545,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>
> if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) {
> local_irq_enable();
> - kvm_timer_sync_hwstate(vcpu);
> kvm_vgic_sync_hwstate(vcpu);
> + kvm_timer_sync_hwstate(vcpu);
> continue;
> }
>
> @@ -577,9 +578,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> * Back from guest
> *************************************************************/
>
> - kvm_timer_sync_hwstate(vcpu);
> kvm_vgic_sync_hwstate(vcpu);
>
> + kvm_timer_sync_hwstate(vcpu);
> +
> ret = handle_exit(vcpu, run, ret);
> }
Reviewed-by: Alex Bennée <alex.bennee at linaro.org>
--
Alex Bennée
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