linux-kernel - Re: [PATCHv5 08/19] x86/mm: Introduce variables to store number, shift and mask of KeyIDs

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Message-ID: <20180720123453.sqz6w5ihaw7gvnoo@kshutemo-mobl1>
Date:   Fri, 20 Jul 2018 15:34:53 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        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: [PATCHv5 08/19] x86/mm: Introduce variables to store number,
 shift and mask of KeyIDs

On Thu, Jul 19, 2018 at 07:23:27AM -0700, Dave Hansen wrote:
> On 07/19/2018 03:21 AM, Kirill A. Shutemov wrote:
> > On Wed, Jul 18, 2018 at 04:19:10PM -0700, Dave Hansen wrote:
> >> On 07/17/2018 04:20 AM, Kirill A. Shutemov wrote:
> >>> mktme_nr_keyids holds number of KeyIDs available for MKTME, excluding
> >>> KeyID zero which used by TME. MKTME KeyIDs start from 1.
> >>>
> >>> mktme_keyid_shift holds shift of KeyID within physical address.
> >> I know what all these words mean, but the combination of them makes no
> >> sense to me.  I still don't know what the variable does after reading this.
> >>
> >> Is this the lowest bit in the physical address which is used for the
> >> KeyID?  How many bits you must shift up a KeyID to get to the location
> >> at which it can be masked into the physical address?
> > Right.
> > 
> > I'm not sure what is not clear from the description. It look fine to me.
> 
> Well, OK, I guess I can write a better one for you.
> 
> "Position in the PTE of the lowest bit of the KeyID"
> 
> It's also a name that could use some love (now that I know what it
> does).  mktme_keyid_pte_shift would be much better.  Or
> mktme_keyid_low_pte_bit.

Okay, thanks.

-- 
 Kirill A. Shutemov