[Xen-devel] [PATCH V2 0/2] Introspection optimization helpers

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

Hello,

This series adds two minor patches. The first one allows finer-grained
control over the emulation behaviour of REP instructions. Previously,
once vm_event-based emulation was enabled, no optimizations were allowed.
However, this has a performance impact on the monitored guest, so I've
added a new libxc function to enable / disable this at will at any point.

The second patch addresses an older issue: in my initial series a few
years back, there was a (longish) patch that computed the length of the
current instruction, and advanced the instruction pointer past it if
it was required by the vm_event reply. However, integrating that code
has not been trivial, and so the second patch in this series simply
allows a vm_event reply to say that the instruction pointer should be
set to whatever value it sends back to the hypervisor. This way, the
computation of the instruction length is left to the userspace
application.

This new version addresses the comments received for V1: the first
patch retires xc_domain_emulate_each_rep() in favour of
xc_monitor_emulate_each_rep(), and the second patch now follows
Tamas' suggestion to replace SET_EIP with SET_REGISTERS and allow
any vm_event reply to set the guest registers (though this currently
only applies to EIP).

[PATCH V2 1/2] xen, libxc: Fine grained control of REP emulation
[PATCH V2 2/2] xen: Introduce VM_EVENT_FLAG_SET_REGISTERS


Thanks,
Razvan

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