[S390] kvm-s390: Fix host crash on misbehaving guests

commit 9ff4cfb3fc ([S390] kvm-390: Let
kernel exit SIE instruction on work) fixed a problem of commit
commit cd3b70f5d4 ([S390] virtualization
aware cpu measurement) but uncovered another one.

If a kvm guest accesses guest real memory that doesnt exist, the
page fault handler calls the sie hook, which then rewrites
the return psw from sie_inst to either sie_exit or sie_reenter.
On return, the page fault handler will then detect the wrong access
as a kernel fault causing a kernel oops in sie_reenter or sie_exit.

We have to add these two addresses to the exception  table to allow
graceful exits.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kvm/sie64a.S

@@ -93,4 +93,6 @@ sie_err:
 
 	.section __ex_table,"a"
 	.quad	sie_inst,sie_err
+	.quad	sie_exit,sie_err
+	.quad	sie_reenter,sie_err
 	.previous