On 15.04.22 12:07, Alex Bennée wrote:
Hello Alex
Oleksandr Tyshchenko olekstysh@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-olekstys... https://lore.kernel.org/xen-devel/1649964960-24864-1-git-send-email-olekstys...
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!