Hi, Xuerui,
On Wed, Feb 14, 2024 at 6:16 PM WANG Xuerui <kernel@xen0n.name> wrote:
>
> From: WANG Xuerui <git@xen0n.name>
>
> All the checks currently done in kvm_check_cpucfg can be realized with
> early returns, so just do that to avoid extra cognitive burden related
> to the return value handling.
>
> The default branch is unreachable because of the earlier validation by
> _kvm_get_cpucfg_mask, so mark it as such too to make things clearer.
>
> Signed-off-by: WANG Xuerui <git@xen0n.name>
> ---
> arch/loongarch/kvm/vcpu.c | 23 +++++++++++------------
> 1 file changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
> index e973500611b4..9e108ffaba30 100644
> --- a/arch/loongarch/kvm/vcpu.c
> +++ b/arch/loongarch/kvm/vcpu.c
> @@ -339,24 +339,23 @@ static int kvm_check_cpucfg(int id, u64 val)
> /* CPUCFG2 features checking */
> if (val & ~mask)
> /* The unsupported features should not be set */
> - ret = -EINVAL;
> - else if (!(val & CPUCFG2_LLFTP))
> + return -EINVAL;
> + if (!(val & CPUCFG2_LLFTP))
> /* The LLFTP must be set, as guest must has a constant timer */
> - ret = -EINVAL;
> - else if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
> + return -EINVAL;
> + if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
> /* Single and double float point must both be set when enable FP */
> - ret = -EINVAL;
> - else if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
> + return -EINVAL;
> + if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
> /* FP should be set when enable LSX */
> - ret = -EINVAL;
> - else if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
> + return -EINVAL;
> + if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
> /* LSX, FP should be set when enable LASX, and FP has been checked before. */
> - ret = -EINVAL;
> - break;
> + return -EINVAL;
> + return 0;
> default:
> - break;
> + unreachable();
Maybe BUG() is better than unreachable()?
Huacai
> }
> - return ret;
> }
>
> static int kvm_get_one_reg(struct kvm_vcpu *vcpu,
> --
> 2.43.0
>