linux-kernel - Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest abstractionn

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Date:   Fri, 4 Jun 2021 15:13:50 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        Borislav Petkov <bp@...en8.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest
 abstractionn



On 6/4/21 3:01 PM, Tom Lendacky wrote:
>>   	 */
>> -	if (sme_active())
>> +	if (protected_guest_has(VM_HOST_MEM_ENCRYPT))
>>   		swiotlb = 1;
> I still feel this is confusing. SME is a host/bare-metal technology, so
> calling protected_guest_has() seems odd and using VM_HOST_MEM_ENCRYPT,
> where I assume VM is short for virtual machine, also seems odd.
> 
> How about just protected_os_has()? Then you could have
> - HOST_MEM_ENCRYPT  for host memory encryption
> - GUEST_MEM_ENCRYPT for guest memory encryption
> - MEM_ENCRYPT       for either host or guest memory encryption.
> 
> The first is analogous to sme_active(), the second to sev_active() and the
> third to mem_encrypt_active(). Just my opinion, though...
> 

I am not sure whether OS makes sense here. But I am fine with it if
it is maintainers choice.

Other option could be protected_boot_has()?

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer