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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <281e1f13-811b-4897-b3d9-18d233af25f7@linux.microsoft.com>
Date:   Fri, 24 Nov 2023 11:00:39 +0100
From:   Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     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>,
        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>, 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: Re: [PATCH v1 3/3] x86/tdx: Provide stub tdx_accept_memory() for
 non-TDX configs

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.