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

[Steven Price <steven.price@arm.com>]

On 04/08/2026 09:57, Aneesh Kumar K.V wrote:
> 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().

Yes that seems like it's slightly neater.

Thanks,
Steve

> 
> -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