x86/irq: Let interrupt handlers set kvm_cpu_l1tf_flush_l1d

The last missing piece to having vmx_l1d_flush() take interrupts after
VMEXIT into account is to set the kvm_cpu_l1tf_flush_l1d per-cpu flag on
irq entry.

Issue calls to kvm_set_cpu_l1tf_flush_l1d() from entering_irq(),
ipi_entering_ack_irq(), smp_reschedule_interrupt() and
uv_bau_message_interrupt().
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicolai Stange <nstange@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/apic.h

@@ -10,6 +10,7 @@
 #include <asm/fixmap.h>
 #include <asm/mpspec.h>
 #include <asm/msr.h>
+#include <asm/hardirq.h>
 
 #define ARCH_APICTIMER_STOPS_ON_C3	1
 
@@ -514,6 +515,7 @@ extern void irq_exit(void);
 static inline void entering_irq(void)
 {
 	irq_enter();
+	kvm_set_cpu_l1tf_flush_l1d();
 }
 
 static inline void entering_ack_irq(void)
@@ -526,6 +528,7 @@ static inline void ipi_entering_ack_irq(void)
 {
 	irq_enter();
 	ack_APIC_irq();
+	kvm_set_cpu_l1tf_flush_l1d();
 }
 
 static inline void exiting_irq(void)

arch/x86/kernel/smp.c

@@ -261,6 +261,7 @@ __visible void __irq_entry smp_reschedule_interrupt(struct pt_regs *regs)
 {
 	ack_APIC_irq();
 	inc_irq_stat(irq_resched_count);
+	kvm_set_cpu_l1tf_flush_l1d();
 
 	if (trace_resched_ipi_enabled()) {
 		/*

arch/x86/platform/uv/tlb_uv.c

@@ -1285,6 +1285,7 @@ void uv_bau_message_interrupt(struct pt_regs *regs)
 	struct msg_desc msgdesc;
 
 	ack_APIC_irq();
+	kvm_set_cpu_l1tf_flush_l1d();
 	time_start = get_cycles();
 
 	bcp = &per_cpu(bau_control, smp_processor_id());