KVM: PPC: Don't always report hash MMU capability for P9 < DD2.2

These machines don't support running both MMU types at the same time,
so remove the KVM_CAP_PPC_MMU_HASH_V3 capability when the host is
using Radix MMU.

[paulus@ozlabs.org - added defensive check on
 kvmppc_hv_ops->hash_v3_possible]
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_ppc.h

@@ -315,6 +315,7 @@ struct kvmppc_ops {
 	int (*enable_svm)(struct kvm *kvm);
 	int (*svm_off)(struct kvm *kvm);
 	int (*enable_dawr1)(struct kvm *kvm);
+	bool (*hash_v3_possible)(void);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;

arch/powerpc/kvm/book3s_hv.c

@@ -5625,6 +5625,15 @@ static int kvmhv_enable_dawr1(struct kvm *kvm)
 	return 0;
 }
 
+static bool kvmppc_hash_v3_possible(void)
+{
+	if (radix_enabled() && no_mixing_hpt_and_radix)
+		return false;
+
+	return cpu_has_feature(CPU_FTR_ARCH_300) &&
+		cpu_has_feature(CPU_FTR_HVMODE);
+}
+
 static struct kvmppc_ops kvm_ops_hv = {
 	.get_sregs = kvm_arch_vcpu_ioctl_get_sregs_hv,
 	.set_sregs = kvm_arch_vcpu_ioctl_set_sregs_hv,
@@ -5669,6 +5678,7 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.enable_svm = kvmhv_enable_svm,
 	.svm_off = kvmhv_svm_off,
 	.enable_dawr1 = kvmhv_enable_dawr1,
+	.hash_v3_possible = kvmppc_hash_v3_possible,
 };
 
 static int kvm_init_subcore_bitmap(void)

arch/powerpc/kvm/powerpc.c

@@ -611,8 +611,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = !!(hv_enabled && radix_enabled());
 		break;
 	case KVM_CAP_PPC_MMU_HASH_V3:
-		r = !!(hv_enabled && cpu_has_feature(CPU_FTR_ARCH_300) &&
-		       cpu_has_feature(CPU_FTR_HVMODE));
+		r = !!(hv_enabled && kvmppc_hv_ops->hash_v3_possible &&
+		       kvmppc_hv_ops->hash_v3_possible());
 		break;
 	case KVM_CAP_PPC_NESTED_HV:
 		r = !!(hv_enabled && kvmppc_hv_ops->enable_nested &&