From: Sean Christopherson sean.j.christopherson@intel.com
commit ee66e453db13d4837a0dcf9d43efa7a88603161b upstream.
...now that VMX's preemption timer, i.e. the hv_timer, also adjusts its programmed time based on lapic_timer_advance_ns. Without the delay, a guest can see a timer interrupt arrive before the requested time when KVM is using the hv_timer to emulate the guest's interrupt.
Fixes: c5ce8235cffa0 ("KVM: VMX: Optimize tscdeadline timer latency") Cc: stable@vger.kernel.org Cc: Wanpeng Li wanpengli@tencent.com Reviewed-by: Liran Alon liran.alon@oracle.com Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/lapic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1453,7 +1453,7 @@ static void apic_timer_expired(struct kv if (swait_active(q)) swake_up_one(q);
- if (apic_lvtt_tscdeadline(apic)) + if (apic_lvtt_tscdeadline(apic) || ktimer->hv_timer_in_use) ktimer->expired_tscdeadline = ktimer->tscdeadline; }