[PATCH v2 08/36] KVM: arm64: Introduce kvm_call_hyp_nvhe_res()

[Jonathan Cameron]

On Fri, 19 Dec 2025 15:52:38 +0000
Sascha Bischoff <Sascha.Bischoff at arm.com> wrote:

> There are times when it is desirable to have more than one return
> value for a hyp call. Split out kvm_call_hyp_nvhe_res from
> kvm_call_hyp_nvhe such that it is possible to directly provide struct
> arm_smccc_res from the calling code. Thereby, additional return values
> can be stored in res.a2, etc.
> 
> Suggested-by: Marc Zyngier <maz at kernel.org>
> Signed-off-by: Sascha Bischoff <sascha.bischoff at arm.com>
One question inline, mostly because I'm curious rather than a suggestion
to change anything

Reviewed-by: Jonathan Cameron <jonathan.cameron at huawei.com>

> ---
>  arch/arm64/include/asm/kvm_host.h | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index b552a1e03848c..971b153b0a3fa 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -1208,14 +1208,19 @@ void kvm_arm_resume_guest(struct kvm *kvm);
>  #define vcpu_has_run_once(vcpu)	(!!READ_ONCE((vcpu)->pid))
>  
>  #ifndef __KVM_NVHE_HYPERVISOR__
> -#define kvm_call_hyp_nvhe(f, ...)						\
> +#define kvm_call_hyp_nvhe_res(res, f, ...)				\
>  	({								\
> -		struct arm_smccc_res res;				\
> -									\
> +		struct arm_smccc_res *__res = res;			\

What's the purpose of the local variable? Type sanity check?
Feels like typecheck() would make the intent clearer.
Meh. Not used anywhere in arch/arm64 so maybe not.



>  		arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(f),		\
> -				  ##__VA_ARGS__, &res);			\
> -		WARN_ON(res.a0 != SMCCC_RET_SUCCESS);			\
> +				  ##__VA_ARGS__, __res);		\
> +		WARN_ON(__res->a0 != SMCCC_RET_SUCCESS);		\
> +	})
> +
> +#define kvm_call_hyp_nvhe(f, ...)					\
> +	({								\
> +		struct arm_smccc_res res;				\
>  									\
> +		kvm_call_hyp_nvhe_res(&res, f, ##__VA_ARGS__);		\
>  		res.a1;							\
>  	})
>