Re: [PATCH 12/22] KVM: arm64: Create helper for stage-1 descriptor updates

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Unused variable `new_desc` left behind after refactoring.
--

commit a77df785da34afbda05fb0cd124ac7baeff877cd
Author: Oliver Upton <oupton@kernel.org>

KVM: arm64: Create helper for stage-1 descriptor updates

This commit prepares for FEAT_HAFT support by creating a descriptor update
helper to be used for both leaf and table descriptors.

> diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
> index 816d23e7752df..0218176107b52 100644
> --- a/arch/arm64/kvm/at.c
> +++ b/arch/arm64/kvm/at.c

[ ... ]

> @@ -617,25 +641,9 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
>  
>  	compute_s1_permissions(vcpu, wi, wr);
>  
> -	if (wi->ha)
> -		new_desc |= PTE_AF;
> -
> -	if (new_desc != ws.desc) {
> -		if (wi->s2 && !ws.s2_trans.writable) {
> -			fail_s1_walk(wr, ESR_ELx_FSC_PERM_L(ws.level), true);
> -			return -EPERM;
> -		}
> -
> -		ret = kvm_swap_s1_desc(vcpu, ws.desc_pa, ws.desc, new_desc, wi);
> -		if (ret == -EAGAIN)
> -			return ret;
> -		if (ret) {
> -			fail_s1_walk(wr, ESR_ELx_FSC_SEA_TTW(ws.level), false);
> -			return ret;
> -		}
> -
> -		ws.desc = new_desc;
> -	}
> +	ret = handle_desc_update(vcpu, wi, &ws, wr, access);
> +	if (ret)
> +		return ret;

[Severity: Low]
Does this leave new_desc unused in walk_s1?

Looking at walk_s1, it appears new_desc is still declared at the top of the 
function and assigned later on, but is no longer read after this change:

walk_s1() {
        u64 va_top, va_bottom, baddr, new_desc, va;
        ...
        new_desc = ws.desc;
        ...
}

Will leaving the declaration and assignment trigger an unused-but-set-variable
compiler warning?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260623184201.1518871-1-oupton@kernel.org?part=12