KVM: PPC: Introduce KVM_CAP_PPC_HTM

Introduce a new KVM capability, KVM_CAP_PPC_HTM, that can be queried to
determine if a PowerPC KVM guest should use HTM (Hardware Transactional
Memory).

This will be used by QEMU to populate the pa-features bits in the
guest's device tree.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/powerpc/kvm/powerpc.c

@@ -588,6 +588,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = 1;
 		break;
 #endif
+	case KVM_CAP_PPC_HTM:
+		r = cpu_has_feature(CPU_FTR_TM_COMP) &&
+		    is_kvmppc_hv_enabled(kvm);
+		break;
 	default:
 		r = 0;
 		break;

include/uapi/linux/kvm.h

@@ -869,6 +869,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_X2APIC_API 129
 #define KVM_CAP_S390_USER_INSTR0 130
 #define KVM_CAP_MSI_DEVID 131
+#define KVM_CAP_PPC_HTM 132
 
 #ifdef KVM_CAP_IRQ_ROUTING