[PATCH v2] KVM: x86: keep eoi exit bitmap accurate before loading it.

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

Guest may mask the IOAPIC entry before issue EOI. In such case,
EOI will not be intercepted by the hypervisor, since the corresponding
bit in eoi_exit_bitmap is not set after the masking of IOAPIC entry.

The solution here is to OR eoi_exit_bitmap with tmr to make sure that
all level-triggered interrupts have their bits in eoi_exit_bitmap set.

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 |   12 ++++++++++++
 arch/x86/kvm/lapic.h |    1 +
 arch/x86/kvm/x86.c   |    1 +
 virt/kvm/ioapic.c    |    7 ++++---
 4 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 8c1162d..0fcac3c 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -539,6 +539,18 @@ void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr)
 	}
 }
 
+void kvm_apic_update_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
+{
+	struct kvm_lapic *apic = vcpu->arch.apic;
+	u32 i;
+	u32 tmr;
+
+	for (i = 0; i < 8; i++) {
+		tmr = kvm_apic_get_reg(apic, APIC_TMR + 0x10 * i);
+		*((u32 *)eoi_exit_bitmap + i) |= tmr;
+	}
+}
+
 static void apic_update_ppr(struct kvm_lapic *apic)
 {
 	u32 tpr, isrv, ppr, old_ppr;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 6a11845..d2b96f2 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -55,6 +55,7 @@ void kvm_apic_set_version(struct kvm_vcpu *vcpu);
 
 void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr);
 void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
+void kvm_apic_update_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
 int kvm_apic_match_physical_addr(struct kvm_lapic *apic, u16 dest);
 int kvm_apic_match_logical_addr(struct kvm_lapic *apic, u8 mda);
 int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d401684..d23b558 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5992,6 +5992,7 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
 
 	kvm_ioapic_scan_entry(vcpu, eoi_exit_bitmap, tmr);
 	kvm_apic_update_tmr(vcpu, tmr);
+	kvm_apic_update_eoi_exitmap(vcpu, eoi_exit_bitmap);
 	kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
 }
 
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index e8ce34c..ed15936 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -254,9 +254,10 @@ void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap,
 	spin_lock(&ioapic->lock);
 	for (index = 0; index < IOAPIC_NUM_PINS; index++) {
 		e = &ioapic->redirtbl[index];
-		if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG ||
-		    kvm_irq_has_notifier(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index) ||
-		    index == RTC_GSI) {
+		if ((!e->fields.mask
+			&& e->fields.trig_mode == IOAPIC_LEVEL_TRIG)
+			|| kvm_irq_has_notifier(ioapic->kvm, KVM_IRQCHIP_IOAPIC,
+				index) || index == RTC_GSI) {
 			if (kvm_apic_match_dest(vcpu, NULL, 0,
 				e->fields.dest_id, e->fields.dest_mode)) {
 				__set_bit(e->fields.vector,
-- 
1.7.1