linux-kernel - Re: [PATCH v4 0/8] Implement generic cc_platform

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Date:   Tue, 28 Sep 2021 14:01:57 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>, Baoquan He <bhe@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Dave Young <dyoung@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Joerg Roedel <joro@...tes.org>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Will Deacon <will@...nel.org>,
        Christoph Hellwig <hch@...radead.org>, x86@...nel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        iommu@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        kexec@...ts.infradead.org
Subject: Re: [PATCH v4 0/8] Implement generic cc_platform_has() helper
 function



On 9/28/21 1:58 PM, Borislav Petkov wrote:
> On Tue, Sep 28, 2021 at 01:48:46PM -0700, Kuppuswamy, Sathyanarayanan wrote:
>> Just read it. If you want to use cpuid_has_tdx_guest() directly in
>> cc_platform_has(), then you want to rename intel_cc_platform_has() to
>> tdx_cc_platform_has()?
> 
> Why?
> 
> You simply do:
> 
> 	if (cpuid_has_tdx_guest())
> 		intel_cc_platform_has(...);
> 
> and lemme paste from that mail: " ...you should use
> cpuid_has_tdx_guest() instead but cache its result so that you don't
> call CPUID each time the kernel executes cc_platform_has()."
> 
> Makes sense?

Yes. But, since the check is related to TDX, I just want to confirm whether
you are fine with naming the function as intel_*().

Since this patch is going to have dependency on TDX code, I will include
this patch in TDX patch set.

> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer