From: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Tue, 16 Apr 2019 20:32:44 +0000 (-0700)
Subject: KVM: lapic: Busy wait for timer to expire when using hv_timer
X-Git-Tag: v4.19.45~10
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=38f114887ca48048a0da736607166a62d5813342;p=platform%2Fkernel%2Flinux-rpi.git

KVM: lapic: Busy wait for timer to expire when using hv_timer

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>
---

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index d2f5aa2..cba414d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1449,7 +1449,7 @@ static void apic_timer_expired(struct kvm_lapic *apic)
 	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;
 }