linux-kernel - Re: [v2][PATCH 2/2] x86/virt/tdx: Fix sparse warnings from using 0 for NULL

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Message-ID: <cea597f3-3a59-4775-b416-f95360d52b0f@intel.com>
Date: Tue, 4 Nov 2025 17:56:23 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Dave Hansen <dave.hansen@...ux.intel.com>, linux-kernel@...r.kernel.org
Cc: Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
 Ingo Molnar <mingo@...hat.com>, "Kirill A. Shutemov" <kas@...nel.org>,
 kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
 Rick Edgecombe <rick.p.edgecombe@...el.com>,
 Sean Christopherson <seanjc@...gle.com>, Thomas Gleixner
 <tglx@...utronix.de>, x86@...nel.org
Subject: Re: [v2][PATCH 2/2] x86/virt/tdx: Fix sparse warnings from using 0
 for NULL

On 11/4/2025 7:44 AM, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> Stop using 0 for NULL.
> 
> sparse moans:
> 
> 	... arch/x86/kvm/vmx/tdx.c:859:38: warning: Using plain integer as NULL pointer
> 
> for several TDX pointer initializations. While I love a good ptr=0
> now and then, it's good to have quiet sparse builds.
> 
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Fixes: a50f673f25e0 ("KVM: TDX: Do TDX specific vcpu initialization")
> Fixes: 8d032b683c29 ("KVM: TDX: create/destroy VM structure")
> Reviewed-by: Rick Edgecombe <rick.p.edgecombe@...el.com>

Reviewed-by: Xiaoyao Li <xiaoyao.li@...el.com>

> Cc: Xiaoyao Li <xiaoyao.li@...el.com>
> Cc: Sean Christopherson <seanjc@...gle.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: x86@...nel.org
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: "Kirill A. Shutemov" <kas@...nel.org>
> Cc: Rick Edgecombe <rick.p.edgecombe@...el.com>
> Cc: kvm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> ---
> 
>   b/arch/x86/kvm/vmx/tdx.c |    6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff -puN arch/x86/kvm/vmx/tdx.c~tdx-sparse-fix-1 arch/x86/kvm/vmx/tdx.c
> --- a/arch/x86/kvm/vmx/tdx.c~tdx-sparse-fix-1	2025-11-03 15:11:28.177643833 -0800
> +++ b/arch/x86/kvm/vmx/tdx.c	2025-11-03 15:11:28.185644508 -0800
> @@ -856,7 +856,7 @@ void tdx_vcpu_free(struct kvm_vcpu *vcpu
>   	}
>   	if (tdx->vp.tdvpr_page) {
>   		tdx_reclaim_control_page(tdx->vp.tdvpr_page);
> -		tdx->vp.tdvpr_page = 0;
> +		tdx->vp.tdvpr_page = NULL;
>   		tdx->vp.tdvpr_pa = 0;
>   	}
>   
> @@ -2642,7 +2642,7 @@ free_tdcs:
>   free_tdr:
>   	if (tdr_page)
>   		__free_page(tdr_page);
> -	kvm_tdx->td.tdr_page = 0;
> +	kvm_tdx->td.tdr_page = NULL;
>   
>   free_hkid:
>   	tdx_hkid_free(kvm_tdx);
> @@ -3016,7 +3016,7 @@ free_tdcx:
>   free_tdvpr:
>   	if (tdx->vp.tdvpr_page)
>   		__free_page(tdx->vp.tdvpr_page);
> -	tdx->vp.tdvpr_page = 0;
> +	tdx->vp.tdvpr_page = NULL;
>   	tdx->vp.tdvpr_pa = 0;
>   
>   	return ret;
> _