linux-kernel - Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

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Message-ID: <20190813080416.GB16770@zn.tnic>
Date:   Tue, 13 Aug 2019 10:04:16 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Isaku Yamahata <isaku.yamahata@...il.com>
Cc:     "Kani, Toshi" <toshi.kani@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "fei1.li@...el.com" <fei1.li@...el.com>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR

On Tue, Aug 13, 2019 at 12:49:20AM -0700, Isaku Yamahata wrote:
> In addition to Xen, KVM+qemu can enable/disable MTRR, PAT independently.
> So user may want to disable MTRR to reduce attack surface.

No, no "user may want" etc vague formulations. Just because some virt
thing "can" do stuff doesn't mean we should change the kernel. What are
the clear benefits of your proposal, why should it go upstream and why
should it be exposed to everybody?

How is going to be used it and what would it bring?

Are there any downsides?

Thx.

-- 
Regards/Gruss,
    Boris.

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