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Re: [Xen-devel] Identifying pagetype in they hypervisor

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Identifying pagetype in they hypervisor
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Mon, 25 Aug 2008 02:10:43 +0100
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I'm looking at the latest code but I would think the same code applies.

Maybe you could try mfn_to_page() to get the struct page_info * and then poke 
about in that for the current type?  In order to make this useful you'd 
probably have to do a get_page or similar to avoid races with other CPUs.


On Monday 25 August 2008 01:47:19 Mike Sun wrote:
> Hi --
> I'm working off of a bit older branch, 3.1.0, but hopefully the
> question is still relevant.
> In the suspend/restore code in 'tools/libxc/xc_domain_save.c', as part
> of the saved record, a list of pfn_types are saved prior to the actual
> pages themselves.  These pfn_types are pfns with a type bits
> associated with them that are accessed with the XEN_DOMCTL_PFINFO_XTAB
> bitmask.
> I'm doing some copy-on-write work, and when I intercept writes in the
> hypervisor, I need to copy both the actual page, and the type
> associated with the page (so that it could later be properly written
> out to the save record).  I've modified the shadow page table code to
> handle write faults associated with CoW and am able to get the mfn of
> the faulting page and perform the copy; I cannot seem to find where
> given the mfn, I can find the page type associated with it.  Could
> anybody help point me to the right place or direction?
> Much thanks,
> Mike
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