A comment might serve future readers.

Signed-off-by: Davidlohr Bueso <[email protected]>
---
 arch/x86/kvm/lapic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 589dcc117086..fb8be28c7093 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1326,6 +1326,12 @@ static void apic_timer_expired(struct kvm_lapic *apic)
        atomic_inc(&apic->lapic_timer.pending);
        kvm_set_pending_timer(vcpu);
 
+       /*
+        * The above kvm_set_pending_timer implies a wmb
+        * which pairs with the swaiter side. Either way,
+        * the atomic_inc() is also serialized so using
+        * swait_active() is safe.
+        */
        if (swait_active(q))
                swake_up(q);
 
-- 
2.12.0

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