KVM: X86: Filter out the broadcast dest for IPI fastpath

Except destination shorthand, a destination value 0xffffffff is used to
broadcast interrupts, let's also filter out this for single target IPI
fastpath.
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1585815626-28370-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -59,9 +59,6 @@
 #define MAX_APIC_VECTOR			256
 #define APIC_VECTORS_PER_REG		32
 
-#define APIC_BROADCAST			0xFF
-#define X2APIC_BROADCAST		0xFFFFFFFFul
-
 static bool lapic_timer_advance_dynamic __read_mostly;
 #define LAPIC_TIMER_ADVANCE_ADJUST_MIN	100	/* clock cycles */
 #define LAPIC_TIMER_ADVANCE_ADJUST_MAX	10000	/* clock cycles */

arch/x86/kvm/lapic.h

@@ -17,6 +17,9 @@
 #define APIC_BUS_CYCLE_NS       1
 #define APIC_BUS_FREQUENCY      (1000000000ULL / APIC_BUS_CYCLE_NS)
 
+#define APIC_BROADCAST			0xFF
+#define X2APIC_BROADCAST		0xFFFFFFFFul
+
 enum lapic_mode {
 	LAPIC_MODE_DISABLED = 0,
 	LAPIC_MODE_INVALID = X2APIC_ENABLE,

arch/x86/kvm/x86.c

@@ -1586,7 +1586,8 @@ static int handle_fastpath_set_x2apic_icr_irqoff(struct kvm_vcpu *vcpu, u64 data
 
 	if (((data & APIC_SHORT_MASK) == APIC_DEST_NOSHORT) &&
 		((data & APIC_DEST_MASK) == APIC_DEST_PHYSICAL) &&
-		((data & APIC_MODE_MASK) == APIC_DM_FIXED)) {
+		((data & APIC_MODE_MASK) == APIC_DM_FIXED) &&
+		((u32)(data >> 32) != X2APIC_BROADCAST)) {
 
 		data &= ~(1 << 12);
 		kvm_apic_send_ipi(vcpu->arch.apic, (u32)data, (u32)(data >> 32));