Re: [Xen-devel] Adding new custom devices to Xen via QEMU

[Wei Liu <wei.liu2@xxxxxxxxxx>]

Hello

On Thu, Sep 29, 2016 at 09:35:21AM -0400, Jason Dickens wrote:
> Hello,
> 
> My name is Jason Dickens and I'm a Research Scientist here at GrammaTech.
> Some of our research involves securing hypervisors and we have needed to add
> to and/or modify Xen. I have been successful in modifying the source for
> various purposes, but my question now is about devices. We have a custom
> device model implemented in QEMU which works great with QEMU (on Intel)
> standalone and with KVM, however, we now want access to it in Xen using the
> same modified QEMU build.
> The only problem I seem to be having is getting Xen to send the MMIO R/W's
> to QEMU. The device is being realized, but guest access to the physical
> address range I expect to reference the device seem to go no place. I see in
> the source calls such as "register_io_handler" that other devices use to
> effect the EPT mapping. Is this what I need?
> My main question is whether or not it is truly necessary to change Xen
> itself in order to introduce new devices in Xen using QEMU, or is there just
> a configuration setting? And what is the simplest way to have a range of

It is most likely achievable by just configuring your PCI device (?) in
QEMU (provided it has a reasonable BAR size or whatnot). Check out
various device model options in xl.cfg manpage, especially
device_model_args= option allows you to add arbitrary options to QEMU.

Wei.

> physical addresses access a custom QEMU device?
> 
> Thanks,
> Jason
> 
> 
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