linux-kernel - Re: [v2][PATCH 1/2] x86/virt/tdx: Remove _

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Message-ID: <aQoqRqb-vN5GxT-x@google.com>
Date: Tue, 4 Nov 2025 08:31:02 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Xiaoyao Li <xiaoyao.li@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>, linux-kernel@...r.kernel.org, 
	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>, Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org
Subject: Re: [v2][PATCH 1/2] x86/virt/tdx: Remove __user annotation from
 kernel pointer

On Tue, Nov 04, 2025, Xiaoyao Li wrote:
> On 11/4/2025 7:44 AM, Dave Hansen wrote:
> > 
> > From: Dave Hansen <dave.hansen@...ux.intel.com>
> > 
> > Separate __user pointer variable declaration from kernel one.
> > 
> > There are two 'kvm_cpuid2' pointers involved here. There's an "input"
> > side: 'td_cpuid' which is a normal kernel pointer and an 'output'
> > side. The output here is userspace and there is an attempt at properly
> > annotating the variable with __user:
> > 
> > 	struct kvm_cpuid2 __user *output, *td_cpuid;
> > 
> > But, alas, this is wrong. The __user in the definition applies to both
> > 'output' and 'td_cpuid'. Sparse notices the address space mismatch and
> > will complain about it.
> > 
> > Fix it up by completely separating the two definitions so that it is
> > obviously correct without even having to know what the C syntax rules
> > even are.
> > 
> > Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> > Fixes: 488808e682e7 ("KVM: x86: Introduce KVM_TDX_GET_CPUID")
> > Reviewed-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> 
> the prefix of the shortlog is still "x86/virt/tdx". I think Sean will change
> it to "KVM: TDX:", if it gets routed through KVM tree.

Ya, I'll fixup when applying.