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[Xen-devel] Exposing MFN to Host (Dom 0)


A few months ago I extended a prototyping hypervisor called Bareflank to
include support for Intel Processor Trace (PT) and now I'm trying to
implement similar functionality in Xen for research. My goal is to
leverage the existing interfaces as much as possible to minimize the
number of direct modifications to the hypervisor code.

I plan to control PT entirely from the host by leveraging libVMI and
writing directly into PT's MSRs, but PT only uses physical addresses, so
the piece that I'm missing is a way for the host to translate a guest
physical address into a machine physical address (GFN => MFN).

Specifically, I need to be able to take the physical address in a
guest's CR3 register and translate it into the machine physical address
and I need a way for host to allocate new pages and get their MFNs so PT
has somewhere to write its trace data.

Carter Yagemann

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