Re: [PATCH 12/13] KVM: PPC: Book3S HV: Move radix MMU switching together in the P9 path

Excerpts from Fabiano Rosas's message of February 25, 2021 6:36 am:

Nicholas Piggin [off-list ref] writes:

quoted

Switching the MMU from radix<->radix mode is tricky particularly as the
MMU can remain enabled and requires a certain sequence of SPR updates.
Move these together into their own functions.

This also includes the radix TLB check / flush because it's tied in to
MMU switching due to tlbiel getting LPID from LPIDR.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---

<snip>

quoted

@@ -4117,7 +4138,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
 {
 	struct kvm_run *run = vcpu->run;
 	int trap, r, pcpu;
-	int srcu_idx, lpid;
+	int srcu_idx;
 	struct kvmppc_vcore *vc;
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_nested_guest *nested = vcpu->arch.nested;

@@ -4191,13 +4212,6 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
 	vc->vcore_state = VCORE_RUNNING;
 	trace_kvmppc_run_core(vc, 0);

-	if (cpu_has_feature(CPU_FTR_HVMODE)) {
-		lpid = nested ? nested->shadow_lpid : kvm->arch.lpid;
-		mtspr(SPRN_LPID, lpid);
-		isync();
-		kvmppc_check_need_tlb_flush(kvm, pcpu, nested);
-	}
-

What about the counterpart to this^ down below?

	if (cpu_has_feature(CPU_FTR_HVMODE)) {
		mtspr(SPRN_LPID, kvm->arch.host_lpid);
		isync();
	}

Good catch, you're right that can be removed too.

Thanks,
Nick