KVM: s390: handle machine checks when guest is running

The low-level interrupt handler on s390 checks for _TIF_WORK_INT and
exits the guest context, if work is pending.
TIF_WORK_INT is defined as_TIF_SIGPENDING | _TIF_NEED_RESCHED |
 _TIF_MCCK_PENDING. Currently the sie loop checks for signals and
reschedule, but it does not check for machine checks. That means that
we exit the guest context if a machine check is pending, but we do not
handle the machine check.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/s390/kvm/kvm-s390.c

@@ -423,13 +423,18 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 	return -EINVAL; /* not implemented yet */
 }
 
+extern void s390_handle_mcck(void);
+
 static void __vcpu_run(struct kvm_vcpu *vcpu)
 {
 	memcpy(&vcpu->arch.sie_block->gg14, &vcpu->arch.guest_gprs[14], 16);
 
 	if (need_resched())
 		schedule();
 
+	if (test_thread_flag(TIF_MCCK_PENDING))
+		s390_handle_mcck();
+
 	vcpu->arch.sie_block->icptcode = 0;
 	local_irq_disable();
 	kvm_guest_enter();

drivers/s390/s390mach.c

@@ -207,6 +207,7 @@ s390_handle_mcck(void)
 		do_exit(SIGSEGV);
 	}
 }
+EXPORT_SYMBOL_GPL(s390_handle_mcck);
 
 /*
  * returns 0 if all registers could be validated