linux-kernel - Re: [patch] paravirt: isolate module ops

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Message-ID: <459EF537.6090301@vmware.com>
Date:	Fri, 05 Jan 2007 17:02:47 -0800
From:	Zachary Amsden <zach@...are.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	Arjan van de Ven <arjan@...radead.org>,
	Adrian Bunk <bunk@...sta.de>
Subject: Re: [patch] paravirt: isolate module ops

Ingo Molnar wrote:
> Subject: [patch] paravirt: isolate module ops
> From: Ingo Molnar <mingo@...e.hu>
>
> only export those operations to modules that have been available to them 
> historically: irq disable/enable, io-delay, udelay, etc.
>
> this isolates that functionality from other paravirtualization 
> functionality that modules have no business messing with.
>
> boot and build tested with CONFIG_PARAVIRT=y.
>   

I would suggest a slightly different carving.  For one, no TLB flushes.  
If you can't modify PTEs, why do you need to have TLB flushes?  And I 
would allow CR0 read / write for code which saves and restores FPU state 
- possibly even debug register access, although any code which touches 
DRs could be doing something sneaky.  I'm on the fence about that one.

Here is a partially tested patch against the -mm tree.  Let me know what 
you think of this slightly different approach.

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