linux-kernel - [PATCH 1/2] x86/virt/tdx: Remove __user annotation from kernel pointer

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Message-Id: <20251029194831.6819B2E7@davehans-spike.ostc.intel.com>
Date: Wed, 29 Oct 2025 12:48:31 -0700
From: Dave Hansen <dave.hansen@...ux.intel.com>
To: linux-kernel@...r.kernel.org
Cc: Dave Hansen <dave.hansen@...ux.intel.com>, 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, Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH 1/2] x86/virt/tdx: Remove __user annotation from kernel pointer

From: Dave Hansen <dave.hansen@...ux.intel.com>

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'.

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>
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 |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -puN arch/x86/kvm/vmx/tdx.c~tdx-sparse-fix-3 arch/x86/kvm/vmx/tdx.c
--- a/arch/x86/kvm/vmx/tdx.c~tdx-sparse-fix-3	2025-10-29 12:10:10.375383704 -0700
+++ b/arch/x86/kvm/vmx/tdx.c	2025-10-29 12:10:10.379384154 -0700
@@ -3054,7 +3054,8 @@ static int tdx_vcpu_get_cpuid_leaf(struc

 static int tdx_vcpu_get_cpuid(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *cmd)
 {
-	struct kvm_cpuid2 __user *output, *td_cpuid;
+	struct kvm_cpuid2 __user *output;
+	struct kvm_cpuid2 *td_cpuid;
 	int r = 0, i = 0, leaf;
 	u32 level;

_