KVM: PPC: Book3S HV: Add 'online' register to ONE_REG interface

This adds a new KVM_REG_PPC_ONLINE register which userspace can set
to 0 or 1 via the GET/SET_ONE_REG interface to indicate whether it
considers the VCPU to be offline (0), that is, not currently running,
or online (1).  This will be used in a later patch to configure the
register which controls PURR and SPURR accumulation.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_host.h

@@ -772,6 +772,8 @@ struct kvm_vcpu_arch {
 	u64 busy_preempt;
 
 	u32 emul_inst;
+
+	u32 online;
 #endif
 
 #ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING

arch/powerpc/include/uapi/asm/kvm.h

@@ -633,6 +633,7 @@ struct kvm_ppc_cpu_char {
 #define KVM_REG_PPC_PSSCR	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xbd)
 
 #define KVM_REG_PPC_DEC_EXPIRY	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xbe)
+#define KVM_REG_PPC_ONLINE	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbf)
 
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs

arch/powerpc/kvm/book3s_hv.c

@@ -1526,6 +1526,9 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 		*val = get_reg_val(id, vcpu->arch.dec_expires +
 				   vcpu->arch.vcore->tb_offset);
 		break;
+	case KVM_REG_PPC_ONLINE:
+		*val = get_reg_val(id, vcpu->arch.online);
+		break;
 	default:
 		r = -EINVAL;
 		break;
@@ -1757,6 +1760,9 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 		vcpu->arch.dec_expires = set_reg_val(id, *val) -
 			vcpu->arch.vcore->tb_offset;
 		break;
+	case KVM_REG_PPC_ONLINE:
+		vcpu->arch.online = set_reg_val(id, *val);
+		break;
 	default:
 		r = -EINVAL;
 		break;