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Message-ID: <281e1f13-811b-4897-b3d9-18d233af25f7@linux.microsoft.com>
Date:   Fri, 24 Nov 2023 11:00:39 +0100
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Subject: Re: [PATCH v1 3/3] x86/tdx: Provide stub tdx_accept_memory() for
 non-TDX configs
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     linux-kernel@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Michael Kelley <mhkelley58@gmail.com>,
        Nikolay Borisov <nik.borisov@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tom Lendacky <thomas.lendacky@amd.com>, x86@kernel.org,
        Dexuan Cui <decui@microsoft.com>, linux-hyperv@vger.kernel.org,
        stefan.bader@canonical.com, tim.gardner@canonical.com,
        roxana.nicolescu@canonical.com, cascardo@canonical.com,
        kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
        sashal@kernel.org, stable@vger.kernel.org
References: <20231122170106.270266-1-jpiotrowski@linux.microsoft.com>
 <20231122170106.270266-3-jpiotrowski@linux.microsoft.com>
 <20231123141113.l3kwputphhj3hxub@box.shutemov.name>
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From:   Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
In-Reply-To: <20231123141113.l3kwputphhj3hxub@box.shutemov.name>
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On 23/11/2023 15:11, Kirill A. Shutemov wrote:
> On Wed, Nov 22, 2023 at 06:01:06PM +0100, Jeremi Piotrowski wrote:
>> 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.
> 
> And who unsets it now?
> 

Who unsets what now? DISABLE_TDX_GUEST still works the same as before, but patch 2
changed the check in arch_accept_memory() to be more specific
(cc_platform_has(CC_ATTR_TDX_MODULE_CALLS)). The stub should have been there all
along for CONFIG_AMD_MEM_ENCRPYT=y && CONFIG_INTEL_TDX_GUEST=n configs, but it
happened to work without it.