KVM: s390: CMMA tracking, ESSA emulation, migration mode

* Add a migration state bitmap to keep track of which pages have dirty
  CMMA information.
* Disable CMMA by default, so we can track if it's used or not. Enable
  it on first use like we do for storage keys (unless we are doing a
  migration).
* Creates a VM attribute to enter and leave migration mode.
* In migration mode, CMMA is disabled in the SIE block, so ESSA is
  always interpreted and emulated in software.
* Free the migration state on VM destroy.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 3dd2a1d..d6879a9 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -70,6 +70,7 @@ struct kvm_s390_io_adapter_req {
 #define KVM_S390_VM_TOD			1
 #define KVM_S390_VM_CRYPTO		2
 #define KVM_S390_VM_CPU_MODEL		3
+#define KVM_S390_VM_MIGRATION		4
 
 /* kvm attributes for mem_ctrl */
 #define KVM_S390_VM_MEM_ENABLE_CMMA	0
@@ -151,6 +152,11 @@ struct kvm_s390_vm_cpu_subfunc {
 #define KVM_S390_VM_CRYPTO_DISABLE_AES_KW	2
 #define KVM_S390_VM_CRYPTO_DISABLE_DEA_KW	3
 
+/* kvm attributes for migration mode */
+#define KVM_S390_VM_MIGRATION_STOP	0
+#define KVM_S390_VM_MIGRATION_START	1
+#define KVM_S390_VM_MIGRATION_STATUS	2
+
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {
 	/* general purpose regs for s390 */