linux-kernel - Re: [PATCH v3 4/6] arm64/kvm: Avoid invalid physical addresses to signal owner updates

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Message-ID: <Z1rJ_dMJJzGOmjNs@google.com>
Date: Thu, 12 Dec 2024 11:33:17 +0000
From: Quentin Perret <qperret@...gle.com>
To: Ard Biesheuvel <ardb+git@...gle.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Ard Biesheuvel <ardb@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Ryan Roberts <ryan.roberts@....com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v3 4/6] arm64/kvm: Avoid invalid physical addresses to
 signal owner updates

On Thursday 12 Dec 2024 at 09:18:46 (+0100), Ard Biesheuvel wrote:
> @@ -908,6 +892,9 @@ static bool stage2_leaf_mapping_allowed(const struct kvm_pgtable_visit_ctx *ctx,
>  	if (data->force_pte && ctx->level < KVM_PGTABLE_LAST_LEVEL)
>  		return false;
>  
> +	if (data->annotation && ctx->level == KVM_PGTABLE_LAST_LEVEL)
> +		return true;
> +

I don't think it's a problem, but what's the rationale for checking
ctx->level here? The data->force_pte logic should already do this for us
and be somewhat orthogonal to data->annotation, no?

Either way, the patch looks good to me

  Reviewed-by: Quentin Perret <qperret@...gle.com>

Cheers,
Quentin

>  	return kvm_block_mapping_supported(ctx, phys);
>  }