Re: [PATCH v3 04/12] Add "handle page fault" PV helper.

From: Gleb Natapov
Date: Mon Jan 18 2010 - 03:51:21 EST

On Mon, Jan 18, 2010 at 12:34:16AM -0800, H. Peter Anvin wrote:
> On 01/17/2010 06:44 AM, Gleb Natapov wrote:
> >On Thu, Jan 14, 2010 at 06:31:07PM +0100, Peter Zijlstra wrote:
> >>On Tue, 2010-01-05 at 16:12 +0200, Gleb Natapov wrote:
> >>>Allow paravirtualized guest to do special handling for some page faults.
> >>>
> >>>The patch adds one 'if' to do_page_fault() function. The call is patched
> >>>out when running on physical HW. I ran kernbech on the kernel with and
> >>>without that additional 'if' and result were rawly the same:
> >>
> >>So why not program a different handler address for the #PF/#GP faults
> >>and avoid the if all together?
> >I would gladly use fault vector reserved by x86 architecture, but I am
> >not sure Intel will be happy about it.
> >
> That's what it's there for... see Peter Z.'s response.
Do you mean I can use one of exception vectors reserved by Intel
(20-31)? What Peter Z says is that I can register my own handler for
#PF and avoid the 'if' in non PV case as far as I understand him.

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