[PATCH v2] KVM: x86: sync old tmr with ioapic to update

[Wei Wang <wei.w.wang@intel.com>]

kvm_ioapic_scan_entry() needs to update tmr. The previous lapic tmr value
(old_tmr) needs to sync with ioapic to get an accurate updated tmr
value before the updating work.

Tested-by: Rongrong Liu <rongrongx.liu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 arch/x86/kvm/lapic.c |   19 +++++++++++++++++--
 arch/x86/kvm/x86.c   |    2 +-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 08e8a89..8c1162d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -518,10 +518,25 @@ static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu)
 void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
+	u32 irr;
+	u32 isr;
+	u32 old_tmr, new_tmr;
 	int i;
 
-	for (i = 0; i < 8; i++)
-		apic_set_reg(apic, APIC_TMR + 0x10 * i, tmr[i]);
+	/*
+	 * The updated tmr value comes from level-triggerd interrupts that
+	 * have already been delieverd to lapic and new coming ones which
+	 * are pending in ioapic. According to the x86 spec, tmr is valid
+	 * when irr or isr is set.
+	 */
+	for (i = 0; i < 8; i++) {
+		irr = kvm_apic_get_reg(apic, APIC_IRR + 0x10 * i);
+		isr = kvm_apic_get_reg(apic, APIC_ISR + 0x10 * i);
+		old_tmr = kvm_apic_get_reg(apic, APIC_TMR + 0x10 * i);
+		new_tmr = (~(irr | isr) & tmr[i])
+				| ((irr | isr) & old_tmr);
+		apic_set_reg(apic, APIC_TMR + 0x10 * i, new_tmr);
+	}
 }
 
 static void apic_update_ppr(struct kvm_lapic *apic)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5f5edb6..d401684 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5991,8 +5991,8 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
 	memset(tmr, 0, 32);
 
 	kvm_ioapic_scan_entry(vcpu, eoi_exit_bitmap, tmr);
-	kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
 	kvm_apic_update_tmr(vcpu, tmr);
+	kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
 }
 
 /*
-- 
1.7.1