[Trusty][SRU][PATCH 1/2] KVM: x86: reset RVI upon system reset

[Seyeong Kim]

From: Wei Wang <wei.w.wang at intel.com>

BugLink: http://bugs.launchpad.net/bugs/1660519

A bug was reported as follows: when running Windows 7 32-bit guests on qemu-kvm,
sometimes the guests run into blue screen during reboot. The problem was that a
guest's RVI was not cleared when it rebooted. This patch has fixed the problem.

Signed-off-by: Wei Wang <wei.w.wang at intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang at intel.com>
Tested-by: Rongrong Liu <rongrongx.liu at intel.com>, Da Chun <ngugc at qq.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(cherry picked from commit 4114c27d450bef228be9c7b0c40a888e18a3a636)
Signed-off-by: Seyeong Kim <seyeong.kim at canonical.com>
---
 arch/x86/kvm/lapic.c |  3 +++
 arch/x86/kvm/vmx.c   | 25 ++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 701fd95..b805ae4 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1692,6 +1692,9 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
 	apic->isr_count = kvm_apic_vid_enabled(vcpu->kvm) ?
 				1 : count_vectors(apic->regs + APIC_ISR);
 	apic->highest_isr_cache = -1;
+	if (kvm_x86_ops->hwapic_irr_update)
+		kvm_x86_ops->hwapic_irr_update(vcpu,
+				apic_find_highest_irr(apic));
 	kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic));
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	kvm_rtc_eoi_tracking_restore_one(vcpu);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 2b45251..6658c0b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6919,6 +6919,9 @@ static void vmx_set_rvi(int vector)
 	u16 status;
 	u8 old;
 
+	if (vector == -1)
+		vector = 0;
+
 	status = vmcs_read16(GUEST_INTR_STATUS);
 	old = (u8)status & 0xff;
 	if ((u8)vector != old) {
@@ -6930,10 +6933,30 @@ static void vmx_set_rvi(int vector)
 
 static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
 {
+	if (!is_guest_mode(vcpu)) {
+		vmx_set_rvi(max_irr);
+		return;
+	}
+
 	if (max_irr == -1)
 		return;
 
-	vmx_set_rvi(max_irr);
+	/*
+	 * In guest mode.  If a vmexit is needed, vmx_check_nested_events
+	 * handles it.
+	 */
+	if (nested_exit_on_intr(vcpu))
+		return;
+
+	/*
+	 * Else, fall back to pre-APICv interrupt injection since L2
+	 * is run without virtual interrupt delivery.
+	 */
+	if (!kvm_event_needs_reinjection(vcpu) &&
+	    vmx_interrupt_allowed(vcpu)) {
+		kvm_queue_interrupt(vcpu, max_irr, false);
+		vmx_inject_irq(vcpu);
+	}
 }
 
 static void vmx_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
-- 
2.7.4