[PATCH] KVM: x86: fix lapic.timer_mode on restore

["Radim Krčmář" <rkrcmar@redhat.com>]

lapic.timer_mode was not properly initialized after migration, which
broke few useful things, like login, by making every sleep eternal.

Fix this by calling apic_update_lvtt in kvm_apic_post_state_restore.

There are other slowpaths that update lvtt, so this patch makes sure
something similar doesn't happen again by calling apic_update_lvtt
after every modification.

Cc: stable@vger.kernel.org
Fixes: f30ebc312ca9 ("KVM: x86: optimize some accesses to LVTT and SPIV")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 arch/x86/kvm/lapic.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index beeef05bb4d9..36e9de1b4127 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1103,6 +1103,17 @@ static void update_divide_count(struct kvm_lapic *apic)
 				   apic->divide_count);
 }
 
+static void apic_update_lvtt(struct kvm_lapic *apic)
+{
+	u32 timer_mode = kvm_apic_get_reg(apic, APIC_LVTT) &
+			apic->lapic_timer.timer_mode_mask;
+
+	if (apic->lapic_timer.timer_mode != timer_mode) {
+		apic->lapic_timer.timer_mode = timer_mode;
+		hrtimer_cancel(&apic->lapic_timer.timer);
+	}
+}
+
 static void apic_timer_expired(struct kvm_lapic *apic)
 {
 	struct kvm_vcpu *vcpu = apic->vcpu;
@@ -1311,6 +1322,7 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 				apic_set_reg(apic, APIC_LVTT + 0x10 * i,
 					     lvt_val | APIC_LVT_MASKED);
 			}
+			apic_update_lvtt(apic);
 			atomic_set(&apic->lapic_timer.pending, 0);
 
 		}
@@ -1343,20 +1355,13 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 
 		break;
 
-	case APIC_LVTT: {
-		u32 timer_mode = val & apic->lapic_timer.timer_mode_mask;
-
-		if (apic->lapic_timer.timer_mode != timer_mode) {
-			apic->lapic_timer.timer_mode = timer_mode;
-			hrtimer_cancel(&apic->lapic_timer.timer);
-		}
-
+	case APIC_LVTT:
 		if (!kvm_apic_sw_enabled(apic))
 			val |= APIC_LVT_MASKED;
 		val &= (apic_lvt_mask[0] | apic->lapic_timer.timer_mode_mask);
 		apic_set_reg(apic, APIC_LVTT, val);
+		apic_update_lvtt(apic);
 		break;
-	}
 
 	case APIC_TMICT:
 		if (apic_lvtt_tscdeadline(apic))
@@ -1588,7 +1593,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 	for (i = 0; i < APIC_LVT_NUM; i++)
 		apic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED);
-	apic->lapic_timer.timer_mode = 0;
+	apic_update_lvtt(apic);
 	if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_LINT0_REENABLED))
 		apic_set_reg(apic, APIC_LVT0,
 			     SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
@@ -1816,6 +1821,7 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
 
 	apic_update_ppr(apic);
 	hrtimer_cancel(&apic->lapic_timer.timer);
+	apic_update_lvtt(apic);
 	update_divide_count(apic);
 	start_apic_timer(apic);
 	apic->irr_pending = true;
-- 
2.4.2