KVM: s390: provide the prefix register via kvm_run

Add the prefix register to the synced register field in kvm_run.
While we need the prefix register most of the time read-only, this
patch also adds handling for guest dirtying of the prefix register.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/s390/include/asm/kvm.h b/arch/s390/include/asm/kvm.h
index 325560a..9fc328c 100644
--- a/arch/s390/include/asm/kvm.h
+++ b/arch/s390/include/asm/kvm.h
@@ -41,7 +41,9 @@
 struct kvm_guest_debug_arch {
 };
 
+#define KVM_SYNC_PREFIX (1UL << 0)
 /* definition of registers in kvm_run */
 struct kvm_sync_regs {
+	__u64 prefix;	/* prefix register */
 };
 #endif