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

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Message-ID: <alpine.DEB.2.21.1807191436300.1602@nanos.tec.linutronix.de>
Date:   Thu, 19 Jul 2018 14:37:35 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
cc:     Dave Hansen <dave.hansen@...el.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "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, 19 Jul 2018, Kirill A. Shutemov wrote:
> On Wed, Jul 18, 2018 at 04:19:10PM -0700, Dave Hansen wrote:
> > >  	} else {
> > >  		/*
> > >  		 * Reset __PHYSICAL_MASK.
> > > @@ -591,6 +592,9 @@ static void detect_tme(struct cpuinfo_x86 *c)
> > >  		 * between CPUs.
> > >  		 */
> > >  		physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
> > > +		mktme_keyid_mask = 0;
> > > +		mktme_keyid_shift = 0;
> > > +		mktme_nr_keyids = 0;
> > >  	}
> > 
> > Should be unnecessary.  These are zeroed by the compiler.
> 
> No. detect_tme() called for each CPU in the system.

And then the variables are cleared out while other CPUs can access them?
How is that supposed to work?

Thanks,

	tglx