linux-kernel - Re: [RESEND RFC 2/2] X86: Use KVM CR pin MSRs

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Message-ID: <20191223120622.GC16710@zn.tnic>
Date:   Mon, 23 Dec 2019 13:06:22 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     John Andersen <john.s.andersen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Christopherson, Sean J" <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>
Subject: Re: [RESEND RFC 2/2] X86: Use KVM CR pin MSRs

On Sun, Dec 22, 2019 at 11:39:19PM -0800, Andy Lutomirski wrote:
> FWIW, I think that handling these details through Kconfig is the wrong
> choice.  Distribution kernels should enable this, and they're not
> going to turn off kexec.

Nope, the other way around is way likely.

> Arguably kexec should be made to work -- there is no fundamental
> reason that kexec should need to fiddle with CR0.WP, for example. But
> a boot option could also work as a short-term option.

The problem with short-term solutions is that they become immutable
once people start using them. So it better be done right from the very
beginning, before it gets exposed.

Thx.

-- 
Regards/Gruss,
    Boris.

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