From: Rusty Russell <rusty@rustcorp.com.au>
Subject: [ofa-general] Re: [kvm-devel] [PATCH][RFC] pte notifiers -- support
	for external page tables
Date: Thu, 06 Sep 2007 05:56:23 +1000
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To: Avi Kivity <avi@qumranet.com>
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On Wed, 2007-09-05 at 22:32 +0300, Avi Kivity wrote:
> [resend due to bad alias expansion resulting in some recipients
>  being bogus]
> 
> Some hardware and software systems maintain page tables outside the normal
> Linux page tables, which reference userspace memory.  This includes
> Infiniband, other RDMA-capable devices, and kvm (with a pending patch).

And lguest.  I can't tell until I've actually implemented it, but I
think it will seriously reduce the need for page pinning which is why
only root can currently launch guests.

My concern is locking: this is called with the page lock held, and I
guess we have to bump the guest out if it's currently running.

(Oh, and this means lguest needs to do a reverse mapping somehow, but
I'll come up with something).

Cheers,
Rusty.