KVM: PPC: Book3S HV P9: Move vcpu register save/restore into functions

This should be no functional difference but makes the caller easier
to read.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-29-npiggin@gmail.com

arch/powerpc/kvm/book3s_hv.c

@@ -4108,6 +4108,44 @@ static void store_spr_state(struct kvm_vcpu *vcpu)
 	vcpu->arch.ctrl = mfspr(SPRN_CTRLF);
 }
 
+/* Returns true if current MSR and/or guest MSR may have changed */
+static bool load_vcpu_state(struct kvm_vcpu *vcpu,
+			   struct p9_host_os_sprs *host_os_sprs)
+{
+	bool ret = false;
+
+	if (cpu_has_feature(CPU_FTR_TM) ||
+	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) {
+		kvmppc_restore_tm_hv(vcpu, vcpu->arch.shregs.msr, true);
+		ret = true;
+	}
+
+	load_spr_state(vcpu, host_os_sprs);
+
+	load_fp_state(&vcpu->arch.fp);
+#ifdef CONFIG_ALTIVEC
+	load_vr_state(&vcpu->arch.vr);
+#endif
+	mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
+
+	return ret;
+}
+
+static void store_vcpu_state(struct kvm_vcpu *vcpu)
+{
+	store_spr_state(vcpu);
+
+	store_fp_state(&vcpu->arch.fp);
+#ifdef CONFIG_ALTIVEC
+	store_vr_state(&vcpu->arch.vr);
+#endif
+	vcpu->arch.vrsave = mfspr(SPRN_VRSAVE);
+
+	if (cpu_has_feature(CPU_FTR_TM) ||
+	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
+		kvmppc_save_tm_hv(vcpu, vcpu->arch.shregs.msr, true);
+}
+
 static void save_p9_host_os_sprs(struct p9_host_os_sprs *host_os_sprs)
 {
 	host_os_sprs->dscr = mfspr(SPRN_DSCR);
@@ -4216,19 +4254,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
 
 	vcpu_vpa_increment_dispatch(vcpu);
 
-	if (cpu_has_feature(CPU_FTR_TM) ||
-	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) {
-		kvmppc_restore_tm_hv(vcpu, vcpu->arch.shregs.msr, true);
-		msr = mfmsr(); /* TM restore can update msr */
-	}
-
-	load_spr_state(vcpu, &host_os_sprs);
-
-	load_fp_state(&vcpu->arch.fp);
-#ifdef CONFIG_ALTIVEC
-	load_vr_state(&vcpu->arch.vr);
-#endif
-	mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
+	if (unlikely(load_vcpu_state(vcpu, &host_os_sprs)))
+		msr = mfmsr(); /* MSR may have been updated */
 
 	switch_pmu_to_guest(vcpu, &host_os_sprs);
 
@@ -4332,17 +4359,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
 
 	switch_pmu_to_host(vcpu, &host_os_sprs);
 
-	store_spr_state(vcpu);
-
-	store_fp_state(&vcpu->arch.fp);
-#ifdef CONFIG_ALTIVEC
-	store_vr_state(&vcpu->arch.vr);
-#endif
-	vcpu->arch.vrsave = mfspr(SPRN_VRSAVE);
-
-	if (cpu_has_feature(CPU_FTR_TM) ||
-	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
-		kvmppc_save_tm_hv(vcpu, vcpu->arch.shregs.msr, true);
+	store_vcpu_state(vcpu);
 
 	vcpu_vpa_increment_dispatch(vcpu);