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Subject: Re: [RFC v1 03/26] x86/cpufeatures: Add is_tdx_guest() interface
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>
Cc:     Andi Kleen <ak@linux.intel.com>,
        Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Raj Ashok <ashok.raj@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        linux-kernel@vger.kernel.org,
        Sean Christopherson <sean.j.christopherson@intel.com>
References: <cover.1612563142.git.sathyanarayanan.kuppuswamy@linux.intel.com>
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From:   Dave Hansen <dave.hansen@intel.com>
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Message-ID: <3aee61d5-9cc2-2c3c-00ea-f3ec7d5f7e04@intel.com>
Date:   Thu, 1 Apr 2021 14:19:03 -0700
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On 4/1/21 2:15 PM, Kuppuswamy, Sathyanarayanan wrote:
> On 4/1/21 2:08 PM, Dave Hansen wrote:
>> On 2/5/21 3:38 PM, Kuppuswamy Sathyanarayanan wrote:
>>> +bool is_tdx_guest(void)
>>> +{
>>> +    return static_cpu_has(X86_FEATURE_TDX_GUEST);
>>> +}
>>
>> Why do you need is_tdx_guest() as opposed to calling
>> cpu_feature_enabled(X86_FEATURE_TDX_GUEST) everywhere?
> 
> is_tdx_guest() is also implemented/used in compressed
> code (which uses native_cpuid calls). I don't think
> we can use cpu_feature_enabled(X86_FEATURE_TDX_GUEST) in
> compressed code right? Also is_tdx_guest() looks easy
> to read and use.

OK, but how many of the is_tdx_guest() uses are in the compressed code?
 Why has its use spread beyond that?