[Rust-VMM] [Stratos-dev] Xen Rust VirtIO demos work breakdown for Project Stratos

Alex Bennée alex.bennee at linaro.org
Fri Apr 15 09:23:20 UTC 2022

Oleksandr Tyshchenko <olekstysh at gmail.com> writes:

> Hello all.
> [Sorry for the possible format issues]
> I have an update regarding (valid) concern which has been also raised in current thread which is the virtio backend's ability (when using
> Xen foreign mapping) to map any guest pages without guest "agreement" on that.
> There is a PoC (with virtio-mmio on Arm) which is based on Juergen Gross’  work to reuse secure Xen grant mapping for the virtio
> communications.
> All details are at:
> https://lore.kernel.org/xen-devel/1649963973-22879-1-git-send-email-olekstysh@gmail.com/
> https://lore.kernel.org/xen-devel/1649964960-24864-1-git-send-email-olekstysh@gmail.com/

Thanks for that. I shall try and find some time to have a look at it.

Did you see Viresh's post about getting our rust-vmm vhost-user backends
working on Xen?

One thing that came up during that work was how guest pages are mapped
into the dom0 domain where Xen needs to use kernel allocated pages via
privcmd rather than then normal shared mmap that is used on KVM. As I
understand it this is to avoid the situation where dom0 may invalidate a
user PTE causing issues for the hypervisor itself. At some point we
would like to fix that wrinkle so we can remove the (minor) hack in
rust-vmm's mmap code to be truly hypervisor agnostic. 

Anyway I hope you and your team are safe and well.

Alex Bennée

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