Re: [Xen-devel] [PATCH] Calculate correct instruction length for data-fault VM exits on VT-x systems

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 29 Apr 2006, at 15:54, Leendert van Doorn wrote:

> The state is already partially exposed to qemu-dm through the shared
> global I/O data page (include/public/hvm/ioreq.h). This is easy to
> extend so that a context switch doesn't involve copying device state.
> This is also the place where we should store the vmx_assist_context
> information that is required by the emulator.
Xen-emulated devices could have their state fetched on demand -- it 
ought to be rare that qemu-dm ends up emulating an access to such a 
device. Or have qemu call down into Xen to emulate those accesses. 
Having a device model duplicated in both Xen and qemu, and 
synchronising between the two, sounds a bit sketchy.
SSE state is another consideration, but maybe that's not too expensive 
to save/restore/copy on every qemu-dm transition.
 -- Keir


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