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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: David Vrabel <david.vrabel@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Pavel Emelyanov <xemul@parallels.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Xen-devel@lists.xen.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Jan Beulich <jbeulich@suse.com>
Subject: Re: Regression: x86/mm: new _PTE_SWP_SOFT_DIRTY bit conflicts with existing use
Date: Wed, 21 Aug 2013 18:12:23 +0400	[thread overview]
Message-ID: <20130821141223.GS18673@moon> (raw)
In-Reply-To: <5214C524.1050900@citrix.com>

On Wed, Aug 21, 2013 at 02:48:20PM +0100, David Vrabel wrote:
> All,
> 
> 179ef71c (mm: save soft-dirty bits on swapped pages) introduces a new
> PTE bit on x86 _PTE_SWP_SOFT_DIRTY which has the same value as _PTE_PSE
> and _PTE_PAT.
> 
> With a Xen PV guest, the use of the _PTE_PAT will result in the page
> having unexpected cachability which will introduce a range of subtle
> performance and correctness issues.  Xen programs the entry 4 in the PAT
> table with WC so a page that was previously WB will end up as WC.
> 

David, could you please explain, Xen keeps and analyze _PTE_PAT bit
for ptes which are not present?

  parent reply	other threads:[~2013-08-21 14:12 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-21 13:48 Regression: x86/mm: new _PTE_SWP_SOFT_DIRTY bit conflicts with existing use David Vrabel
2013-08-21 13:53 ` konrad wilk
2013-08-21 13:53 ` konrad wilk
2013-08-21 14:11 ` H. Peter Anvin
2013-08-21 14:19   ` Cyrill Gorcunov
2013-08-21 14:19   ` Cyrill Gorcunov
2013-08-21 14:22     ` H. Peter Anvin
2013-08-21 14:29       ` Cyrill Gorcunov
2013-08-21 14:29       ` Cyrill Gorcunov
2013-08-21 14:22     ` H. Peter Anvin
2013-08-21 16:30     ` Linus Torvalds
2013-08-21 16:30     ` Linus Torvalds
2013-08-21 16:42       ` Cyrill Gorcunov
2013-08-21 16:42       ` Cyrill Gorcunov
2013-08-21 23:05       ` Cyrill Gorcunov
2013-08-21 23:05       ` Cyrill Gorcunov
2013-08-21 23:42         ` Andi Kleen
2013-08-21 23:42         ` Andi Kleen
2013-08-22  5:49           ` Cyrill Gorcunov
2013-08-22  6:37             ` Minchan Kim
2013-08-22  6:37             ` Minchan Kim
2013-08-22 13:12               ` Cyrill Gorcunov
2013-08-22 13:12               ` Cyrill Gorcunov
2013-08-22  5:49           ` Cyrill Gorcunov
2013-08-27 22:04       ` Benjamin Herrenschmidt
2013-08-27 22:04       ` Benjamin Herrenschmidt
2013-08-21 14:11 ` H. Peter Anvin
2013-08-21 14:12 ` Cyrill Gorcunov [this message]
2013-08-21 14:22   ` H. Peter Anvin
2013-08-21 14:22   ` H. Peter Anvin
2013-08-21 14:53   ` Jan Beulich
2013-08-21 14:58     ` H. Peter Anvin
2013-08-21 14:58     ` H. Peter Anvin
2013-08-21 15:42     ` Cyrill Gorcunov
2013-08-21 16:03       ` Jan Beulich
2013-08-21 16:03       ` Jan Beulich
2013-08-21 16:19         ` Cyrill Gorcunov
2013-08-21 16:56           ` David Vrabel
2013-08-21 17:25             ` Cyrill Gorcunov
2013-08-21 18:17               ` Cyrill Gorcunov
2013-08-21 18:50                 ` H. Peter Anvin
2013-08-21 19:03                   ` Cyrill Gorcunov
2013-08-21 19:07                     ` Andy Lutomirski
2013-08-21 19:20                       ` Cyrill Gorcunov
2013-08-21 19:20                       ` Cyrill Gorcunov
2013-08-21 19:21                       ` Pavel Emelyanov
2013-08-21 19:21                       ` Pavel Emelyanov
2013-08-21 19:07                     ` Andy Lutomirski
2013-08-21 23:04                     ` Linus Torvalds
2013-08-21 23:04                     ` Linus Torvalds
2013-08-22  0:51                       ` Dave Jones
2013-08-22  0:51                       ` Dave Jones
2013-08-22  5:44                         ` Cyrill Gorcunov
2013-08-22  5:44                         ` Cyrill Gorcunov
2013-08-22  6:41                         ` Pavel Emelyanov
2013-08-22  6:41                         ` Pavel Emelyanov
2013-08-22  7:47                       ` Jan Beulich
2013-08-22  7:47                       ` Jan Beulich
2013-08-22  9:32                       ` David Vrabel
2013-08-22  9:32                       ` David Vrabel
2013-08-22 10:16                         ` Pavel Emelyanov
2013-08-22 10:16                         ` Pavel Emelyanov
2013-08-21 19:03                   ` Cyrill Gorcunov
2013-08-21 18:50                 ` H. Peter Anvin
2013-08-21 18:17               ` Cyrill Gorcunov
2013-08-21 17:25             ` Cyrill Gorcunov
2013-08-21 16:56           ` David Vrabel
2013-08-22  6:56           ` Jan Beulich
2013-08-22  7:03             ` Cyrill Gorcunov
2013-08-22  7:27               ` Jan Beulich
2013-08-22  7:27               ` Jan Beulich
2013-08-22 11:27                 ` Cyrill Gorcunov
2013-08-22 11:27                 ` Cyrill Gorcunov
2013-08-22 11:33                   ` Jan Beulich
2013-08-22 11:33                   ` Jan Beulich
2013-08-22 12:18                     ` Pavel Emelyanov
2013-08-22 12:18                     ` Pavel Emelyanov
2013-08-22  7:03             ` Cyrill Gorcunov
2013-08-22  6:56           ` Jan Beulich
2013-08-21 16:19         ` Cyrill Gorcunov
2013-08-21 15:42     ` Cyrill Gorcunov
2013-08-21 14:53   ` Jan Beulich
2013-08-21 14:12 ` Cyrill Gorcunov
2013-08-21 17:28 ` Andy Lutomirski
2013-08-21 17:28 ` Andy Lutomirski
2013-08-22  7:54   ` Jan Beulich
2013-08-22  9:06     ` Stefan Bader
2013-08-22  7:54   ` Jan Beulich
  -- strict thread matches above, loose matches on Subject: below --
2013-08-21 13:48 David Vrabel

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