linux-kernel - [PATCH v1 3/3] x86/tdx: Provide stub tdx_accept

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Message-Id: <20231122170106.270266-3-jpiotrowski@linux.microsoft.com>
Date:   Wed, 22 Nov 2023 18:01:06 +0100
From:   Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
To:     linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Michael Kelley <mhkelley58@...il.com>,
        Nikolay Borisov <nik.borisov@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>, x86@...nel.org,
        Dexuan Cui <decui@...rosoft.com>
Cc:     Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>,
        linux-hyperv@...r.kernel.org, stefan.bader@...onical.com,
        tim.gardner@...onical.com, roxana.nicolescu@...onical.com,
        cascardo@...onical.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        wei.liu@...nel.org, sashal@...nel.org, stable@...r.kernel.org
Subject: [PATCH v1 3/3] x86/tdx: Provide stub tdx_accept_memory() for non-TDX configs

When CONFIG_INTEL_TDX_GUEST is not defined but CONFIG_UNACCEPTED_MEMORY=y is,
the kernel fails to link with an undefined reference to tdx_accept_memory from
arch_accept_memory. Provide a stub for tdx_accept_memory to fix the build for
that configuration.

CONFIG_UNACCEPTED_MEMORY is also selected by CONFIG_AMD_MEM_ENCRYPT, and there
are stubs for snp_accept_memory for when it is not defined. Previously this did
not result in an error when CONFIG_INTEL_TDX_GUEST was not defined because the
branch that references tdx_accept_memory() was being discarded due to
DISABLE_TDX_GUEST being set.

Cc: <stable@...r.kernel.org> # v6.5+
Fixes: 75d090fd167a ("x86/tdx: Add unaccepted memory support")
Signed-off-by: Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
---
 arch/x86/include/asm/shared/tdx.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 7513b3bb69b7..58cdbaac3d5b 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -91,7 +91,11 @@ struct tdx_module_output {
 u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
 		      struct tdx_module_output *out);
 
+#ifdef CONFIG_INTEL_TDX_GUEST
 bool tdx_accept_memory(phys_addr_t start, phys_addr_t end);
+#else
+static inline bool tdx_accept_memory(phys_addr_t start, phys_addr_t end) { return false; }
+#endif
 
 /*
  * The TDG.VP.VMCALL-Instruction-execution sub-functions are defined
-- 
2.39.2