linux-kernel - Re: [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature

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Message-ID: <20211014002506.2rqkgzrvy5ki2rcw@treble>
Date:   Wed, 13 Oct 2021 17:25:06 -0700
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Borislav Petkov <bp@...en8.de>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Juergen Gross <jgross@...e.com>, Deep Shah <sdeep@...are.com>,
        VMware Inc <pv-drivers@...are.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Peter H Anvin <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature

On Thu, Oct 14, 2021 at 01:19:23AM +0200, Thomas Gleixner wrote:
> I'm amazed that it's so hard to see that this
> 
>     use()
>     init()
> 
> pattern is broken to begin with.
> 
> So why are you arguing about the placement of this variable in the first
> place instead of actually looking at the code, wondering about the
> obscenity and then asking about the call ordering?
> 
> In case that I might miss something important here due to my lack of CS
> education, please let me know.

I agree that's better.

I'd suggested doing setup_force_cpu_cap(X86_FEATURE_TDX_GUEST) early,
and then just check that instead of needing this new static variable.  I
think Boris said that's not possible because of some ordering reasons
which are eluding me (and I didn't have time to investigate).

-- 
Josh