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

[Oleksandr <olekstysh@xxxxxxxxx>]

On 15.04.22 12:07, Alex Bennée wrote:


Hello Alex

> Oleksandr Tyshchenko <olekstysh@xxxxxxxxx> 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@xxxxxxxxx/
> > https://lore.kernel.org/xen-devel/1649964960-24864-1-git-send-email-olekstysh@xxxxxxxxx/
> 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?
Great work! I see the email in my mailbox, but didn't analyze it yet. I 
will definitely take a look at it.

> 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.
Thank you!


>
--
Regards,

Oleksandr Tyshchenko