linux-kernel - Re: [RFC v2 28/32] x86/tdx: Make pages shared in ioremap()

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Date:   Tue, 1 Jun 2021 14:16:27 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Raj Ashok <ashok.raj@...el.com>, linux-kernel@...r.kernel.org,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [RFC v2 28/32] x86/tdx: Make pages shared in ioremap()

Hi,

On 5/31/21 12:14 PM, Borislav Petkov wrote:
>> We can also use protected_guest_has(VM_VIRTIO_SECURE_FIX) or something
>> similar for this purpose. Andi, any comments?
> protected_guest_has() is enough for that - no need for two functions.
> 
>> IMHO, its better to use above generic config option in common header
>> file (linux/protected_guest.h). Any architecture that implements
>> protected guest feature can enable it. This will help is hide arch
>> specific config options in arch specific header file.
> You define empty function stubs for when the arch config option is not
> enabled. Everything else is unnecessary. When another architecture needs
> this, then another architecture will generalize it like it is usually
> done.

Please check the updated version in email titled "[RFC v2-fix-v2 1/1] x86:
Introduce generic protected guest abstraction".

We can continue the rest of the discussion in that email.

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer