Re: [PATCH v16 21/45] KVM: arm64: CCA: Handle realm enter/exit

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Steven Price <steven.price@arm.com> writes:

> +	switch (rec->run->exit.exit_reason) {
> +	case RMI_EXIT_SYNC:
> +		/*
> +		 * HPFAR_EL2_NS is hijacked to indicate a valid HPFAR value,
> +		 * see __get_fault_info()
> +		 */
> +		vcpu->arch.fault.hpfar_el2 = rec->run->exit.hpfar | HPFAR_EL2_NS;
> +		rec_exit_sync(vcpu);
> +		return ARM_EXCEPTION_TRAP;
> +	case RMI_EXIT_IRQ:
> +	case RMI_EXIT_FIQ:
> +		return ARM_EXCEPTION_IRQ;
> +	case RMI_EXIT_SERROR:
> +		return ARM_EXCEPTION_EL1_SERROR;
> +	case RMI_EXIT_PSCI:
> +		rec_exit_hvc(vcpu);
> +		kvm_make_request(KVM_REQ_RMI, vcpu);
> +		return ARM_EXCEPTION_TRAP;
> +	case RMI_EXIT_RIPAS_CHANGE:
> +		rec_exit_hvc(vcpu);
> +		return ARM_EXCEPTION_TRAP;
> +	}

Should we handle RMI_EXIT_RIPAS_CHANGE differently? Currently, the call path is:

kvm_rec_exit()
-> RMI_EXIT_RIPAS_CHANGE
-> handle_hvc()
-> kvm_rec_handle_hvc()
-> kvm_prepare_memory_fault_exit()

Could we instead treat RMI_EXIT_RIPAS_CHANGE as a special case and avoid
redirecting it through handle_hvc()? The completion part of the RIPAS
change could still be handled by kvm_rec_handle_request().


-bool kvm_rec_handle_hvc(struct kvm_vcpu *vcpu, int *ret)
+static int rec_exit_ripas_change(struct kvm_vcpu *vcpu)
 {
-	struct realm_rec *rec;
+	struct realm_rec *rec = &vcpu->arch.rec;
 	struct realm *realm;
 	unsigned long base;
 	unsigned long ripas;
 	unsigned long top;
 
-	if (!vcpu_is_rec(vcpu))
-		return false;
-
-	rec = &vcpu->arch.rec;
-	if (rec->run->exit.exit_reason != RMI_EXIT_RIPAS_CHANGE)
-		return false;
-
 	realm = &vcpu->kvm->arch.realm;
 	base = rec->run->exit.ripas_base;
 	top = rec->run->exit.ripas_top;
@@ -89,8 +83,7 @@ bool kvm_rec_handle_hvc(struct kvm_vcpu *vcpu, int *ret)
 			 base, top, ripas);
 		/* Set RMI_REJECT bit */
 		rec->run->enter.flags = REC_ENTER_FLAG_RIPAS_RESPONSE;
-		*ret = -EINVAL;
-		return true;
+		return -EINVAL;
 	}
 
 	/* Exit to VMM, the actual RIPAS change is done on next entry */
@@ -102,8 +95,7 @@ bool kvm_rec_handle_hvc(struct kvm_vcpu *vcpu, int *ret)
 	 * KVM_EXIT_MEMORY_FAULT requires a return code of -EFAULT, see the
 	 * API documentation
 	 */
-	*ret = -EFAULT;
-	return true;
+	return -EFAULT;
 }
 
 int kvm_rec_exit(struct kvm_vcpu *vcpu, int rec_run_ret)
@@ -169,8 +161,7 @@ int kvm_rec_exit(struct kvm_vcpu *vcpu, int rec_run_ret)
 		kvm_make_request(KVM_REQ_RMI, vcpu);
 		return ARM_EXCEPTION_TRAP;
 	case RMI_EXIT_RIPAS_CHANGE:
-		rec_exit_hvc(vcpu);
-		return ARM_EXCEPTION_TRAP;
+		return rec_exit_ripas_change(vcpu);
 	}
 
 	return rec_exit_fatal(vcpu, "Unsupported Realm exit reason",

-aneesh