linux-kernel - Re: [PATCHv3 17/17] x86: Introduce CONFIG_X86_INTEL

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Message-ID: <20180618134100.iehlv2uw4n7ariro@black.fi.intel.com>
Date:   Mon, 18 Jun 2018 16:41:00 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv3 17/17] x86: Introduce CONFIG_X86_INTEL_MKTME

On Wed, Jun 13, 2018 at 06:46:34PM +0000, Dave Hansen wrote:
> On 06/12/2018 07:39 AM, Kirill A. Shutemov wrote:
> > Add new config option to enabled/disable Multi-Key Total Memory
> > Encryption support.
> > 
> > MKTME uses MEMORY_PHYSICAL_PADDING to reserve enough space in per-KeyID
> > direct mappings for memory hotplug.
> 
> Isn't it really *the* direct mapping primarily?  We make all of them
> larger, but the direct mapping is impacted too.  This makes it sound
> like it applies only to the MKTME mappings.

We only cares about the padding in two cases: MKTME and KALSR.
If none of them enabled padding doesn't have meaning. We have PAGE_OFFSET
at fixed address and size is also fixed.

-- 
 Kirill A. Shutemov