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RE: [Xen-devel] TPR write optimization (even improves 2003 sp2)

To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] TPR write optimization (even improves 2003 sp2)
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Thu, 8 Jan 2009 20:17:59 +1100
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Thread-topic: [Xen-devel] TPR write optimization (even improves 2003 sp2)
> On 08/01/2009 09:09, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
wrote:
> 
> >> Using alloc_xenheap_page would be okay.
> >
> > Is it possible to map a page allocated with alloc_domheap_page into
the
> > domain? The semantics must be different as it didn't work the way I
> > expected it to...
> 
> OTOH I think Intel's FlexPriority depends on us using
> alloc_domheap_pages(),
> so we may have an issue both ways round here.

I was afraid of that - I guess that's where the vmx side of things uses
the regs_page.

> The other issue with giving
> the guest write access to the APIC page is whether Xen can deal with
> random
> crap being written over it. Might need to audit vlapic.c for that.

Are you concerned about an errant (or malicious) DomU crashing the
vlapic code (and therefore Xen)? That was something I hadn't thought
of...

James

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