linux-kernel - Re: [PATCH v1 2/3] x86/coco: Disable TDX module calls when TD partitioning is active

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Message-ID: <20231123141318.rmskhl3scc2a6muw@box.shutemov.name>
Date:   Thu, 23 Nov 2023 17:13:18 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Jeremi Piotrowski <jpiotrowski@...ux.microsoft.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 2/3] x86/coco: Disable TDX module calls when TD
 partitioning is active

On Wed, Nov 22, 2023 at 06:01:05PM +0100, Jeremi Piotrowski wrote:
> Introduce CC_ATTR_TDX_MODULE_CALLS to allow code to check whether TDX module
> calls are available. When TD partitioning is enabled, a L1 TD VMM handles most
> TDX facilities and the kernel running as an L2 TD VM does not have access to
> TDX module calls. The kernel still has access to TDVMCALL(0) which is forwarded
> to the VMM for processing, which is the L1 TD VM in this case.

Sounds like a problem introduced by patch 1/3 :/

-- 
  Kiryl Shutsemau / Kirill A. Shutemov