KVM: PPC: Book3S HV: Add NO_HASH flag to GET_SMMU_INFO ioctl result

This adds a KVM_PPC_NO_HASH flag to the flags field of the
kvm_ppc_smmu_info struct, and arranges for it to be set when
running as a nested hypervisor, as an unambiguous indication
to userspace that HPT guests are not supported.  Reporting the
KVM_CAP_PPC_MMU_HASH_V3 capability as false could be taken as
indicating only that the new HPT features in ISA V3.0 are not
supported, leaving it ambiguous whether pre-V3.0 HPT features
are supported.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

Documentation/virtual/kvm/api.txt

@@ -2270,6 +2270,10 @@ The supported flags are:
         The emulated MMU supports 1T segments in addition to the
         standard 256M ones.
 
+    - KVM_PPC_NO_HASH
+	This flag indicates that HPT guests are not supported by KVM,
+	thus all guests must use radix MMU mode.
+
 The "slb_size" field indicates how many SLB entries are supported
 
 The "sps" array contains 8 entries indicating the supported base