linux-kernel - Re: [PATCH RESEND] KVM: TDX: Use struct_size and simplify tdx_get

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Message-Id: <79605B58-CBB6-460D-8B72-F648F962E1BA@linux.dev>
Date: Wed, 12 Nov 2025 22:22:02 +0100
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc: "seanjc@...gle.com" <seanjc@...gle.com>,
 "x86@...nel.org" <x86@...nel.org>,
 "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
 "bp@...en8.de" <bp@...en8.de>,
 "mingo@...hat.com" <mingo@...hat.com>,
 "tglx@...utronix.de" <tglx@...utronix.de>,
 "hpa@...or.com" <hpa@...or.com>,
 "pbonzini@...hat.com" <pbonzini@...hat.com>,
 "kas@...nel.org" <kas@...nel.org>,
 "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
 "linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] KVM: TDX: Use struct_size and simplify
 tdx_get_capabilities

On 12. Nov 2025, at 20:59, Edgecombe, Rick P wrote:
> It looks like you are conducting a treewide pattern matching cleanup?

Just a few instances here and there, but not really treewide.

> In the handling of get_user(nr_user_entries, &user_caps->cpuid.nent), the old
> code forced -EFAULT, this patch doesn't. But it leaves the copy_to_user()'s to
> still force EFAULT. Why?

get_user() already returns -EFAULT and the error can just be forwarded,
whereas copy_to_user() returns the number of bytes that could not be
copied and we must return -EFAULT manually.

> Tested-by: Rick Edgecombe <rick.p.edgecombe@...el.com> (really the TDX CI)

Thanks,
Thorsten