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Date:   Wed, 6 Oct 2021 07:11:05 -0700
From:   Josh Poimboeuf <jpoimboe@redhat.com>
To:     Borislav Petkov <bp@alien8.de>
Cc:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Juergen Gross <jgross@suse.com>, Deep Shah <sdeep@vmware.com>,
        VMware Inc <pv-drivers@vmware.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, Peter H Anvin <hpa@zytor.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 03/11] x86/cpufeatures: Add TDX Guest CPU feature
Message-ID: <20211006141105.offh3fqhyupzqs7v@treble>
References: <20211005025205.1784480-1-sathyanarayanan.kuppuswamy@linux.intel.com>
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 <20211006034218.ynamwigsvpgad7sr@treble>
 <f15d1b41-e4fb-0203-88f7-dbac3f4e5307@linux.intel.com>
 <20211006050309.ldn5myznmpurnomm@treble>
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On Wed, Oct 06, 2021 at 02:47:42PM +0200, Borislav Petkov wrote:
> On Tue, Oct 05, 2021 at 10:03:09PM -0700, Josh Poimboeuf wrote:
> > I'm not suggesting getting rid of the feature flag.  I'm suggesting
> > getting rid of the global variable.  Is there a reason you can't check
> > the feature flag instead of checking the global variable?
> 
> The reason is that cc_platform_has() is used too early, even before
> get_cpu_cap(). So you need to have TDX guest detected even before
> feature flags.

Ok.  At least it sounds like cc_platform_has() needs a comment stating
that caps can't be relied on, and why.

-- 
Josh