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[Xen-devel] Walking guest page tables...

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Walking guest page tables...
From: Matthew Donovan <matthew@xxxxxxxxxxxxxx>
Date: Tue, 22 Jul 2008 10:23:17 -0400
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I'm working on a security application and we want to be able to specify
guest memory addresses to monitor.  When those addresses (or address range)
get written, a notification is sent to the user application in dom0.
Currently, we're doing this by mapping pages and polling but that's sort of
ugly.

In general, I believe all I have to do is walk the guest's page tables and
mark the pages of interest as read-only.  Then, when the guest attempts to
write to the page, we can check the address in the page fault handler and if
it an address we care about, notify the user and pass the write operation
along.

Is it possible to walk an HVM guest's page tables?  Can someone point me to
code that does it?

I read that the dirty page logging that occurs during live migration starts
by making all the pages readonly but when I trace the code for
paging_log_dirty_enable(), it doesn't look like that's happening.

Thanks
-matthew

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