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Re: [Xen-devel] [RFC] scf: SCF device tree and configuration documentation

On 04/05/17 11:03, Andrii Anisov wrote:
Dear All,

Hi Andrii,

During the topic implementation I faced a nasty issue with a DomU vgic
Originally I planned that the partial device tree for DomU is being
passed to the
hypervisor from libxl__arch_domain_create, but it is too late to set
vgic configuration
at this time. The DomU’s vgic is configured from
libxl_arch_domain_prepare_config, and
now it seems it is a proper place to send device_tree to a hypervisor as
a part of

I am not going to comment on the binding itself, but the idea of sending a device_tree to the hypervisor as part of configuration.

As you may have seen in the description of the option "device_tree", it is complex to verify the partial device tree because of the libfdt design. So without fully auditing libfdt and fixing the holes, this suggestion would be a vector attack to the hypervisor.

Whilst I do agree that this could be an interface between the user and the toolstack, we shall look into introducing a series of DOMCTL for the toolstack <-> hypervisor. What would be the issue to do that?


Provided that I need the device tree blob even later,
during device
tree creation for domU (in libxl_prepare_dtb) I would like to have it
read from a file
once and keep it during guest domain creation process.

My problem is that domain creation functions stack mainly operates with
auto generated
structures. For my current understanding it means that I have to
introduce another
libxl type (f.e. File) which will read device tree file and operate with
a binary blob.

Understanding the complexity of such a change I would like to hear
comments about the
SCF configuration concept and feasibility of passing device tree blob
from toolstack
to hypervisor as a part of domain configuration.

*Andrii Anisov*

Julien Grall

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