linux-kernel - Re: [PATCH v2 2/8] x86/mtrr: support setting MTRR state for software defined MTRRs

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Message-ID: <6f561386-9bc4-a3bf-656d-db27a2275413@suse.com>
Date:   Tue, 14 Feb 2023 08:04:47 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        lists@...dbynature.de, mikelley@...rosoft.com,
        torvalds@...ux-foundation.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 2/8] x86/mtrr: support setting MTRR state for software
 defined MTRRs

On 13.02.23 19:53, Borislav Petkov wrote:
> On Mon, Feb 13, 2023 at 04:44:09PM +0100, Juergen Gross wrote:
>> Okay, and it has MTRRs enabled (as Hyper-V SEV-SNP guests), so I shouldn't
>> test that, I guess (or we should disable the feature before calling the
>> overwrite function).
> 
> I think we should handle TDX the same way - as if the MTRRs are
> read-only there. So you can check X86_FEATURE_TDX_GUEST in addition.

Okay, if you really want to dictate the allowed use cases (this seems to be
a layering violation), but you are the maintainer of that code.


Juergen


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