linux-kernel - Re: [PATCH 0 of 4] mm+paravirt+xen: add pte read-modify-write abstraction

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Message-ID: <48409847.4000902@goop.org>
Date:	Sat, 31 May 2008 01:13:59 +0100
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Zachary Amsden <zach@...are.com>
CC:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	xen-devel <xen-devel@...ts.xensource.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Hugh Dickins <hugh@...itas.com>,
	kvm-devel <kvm-devel@...ts.sourceforge.net>,
	Virtualization Mailing List <virtualization@...ts.osdl.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 0 of 4] mm+paravirt+xen: add pte	read-modify-write	abstraction

Zachary Amsden wrote:
> We don't fault.  We write directly to the primary page tables, and clear
> the pte just like native.  We just issue all mprotect updates in the
> queue, and flush the queue when leaving lazy mmu mode.  You can't wait
> for the TLB flush, you must flush the updates before releasing the
> pagetable lock, or you could get misordered updates in an SMP system.
>   

How do you track which ptes need shadow updates?  Do you walk the entire 
pagetable on tlb flush?  Or just rebuild the shadow from scratch on demand?

    J
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