arm/arm64: KVM: Fix ordering of timer/GIC on guest entry

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@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9ce5cf02ed17..1141d21b7e3c 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -523,8 +523,8 @@ 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);
 
                 preempt_disable();
                 local_irq_disable();
@@ -540,8 +540,8 @@ 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();
                         preempt_enable();
-                        kvm_timer_sync_hwstate(vcpu);
                         kvm_vgic_sync_hwstate(vcpu);
+                        kvm_timer_sync_hwstate(vcpu);
                         continue;
                 }
 
@@ -587,9 +587,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
                 trace_kvm_exit(kvm_vcpu_trap_get_class(vcpu), *vcpu_pc(vcpu));
                 preempt_enable();
 
-
-                kvm_timer_sync_hwstate(vcpu);
                 kvm_vgic_sync_hwstate(vcpu);
+                kvm_timer_sync_hwstate(vcpu);
 
                 ret = handle_exit(vcpu, run, ret);
         }