Re: Virtio on Xen with Rust

[Viresh Kumar <viresh.kumar@xxxxxxxxxx>]

On 28-04-22, 16:52, Oleksandr Tyshchenko wrote:
> Great work!

Thanks Oleksandr.

> I skimmed through your toolstack patches, awesome, you created a completely
> new virtual device "I2C".

I have also created GPIO now :)

What should I do about these patches ? Send them to xen list ? I can at least
send the stuff which doesn't depend on your series ?

> FYI, I have updated "Virtio support for toolstack on Arm" [1] since (to
> make it more generic), now V7 is available and I have a plan to push V8
> soon.

I will surely have a look, thanks.

> FYI, currently we are working on one feature to restrict memory access
> using Xen grant mappings based on xen-grant DMA-mapping layer for Linux [1].
> And there is a working PoC on Arm based on an updated virtio-disk. As for
> libraries, there is a new dependency on "xengnttab" library. In comparison
> with Xen foreign mappings model (xenforeignmemory),
> the Xen grant mappings model is a good fit into the Xen security model,
> this is a safe mechanism to share pages between guests.

Right, I was aware of this work but didn't dive into it yet. We will surely need
to do that eventually, lets see when I will be able to get to that. The current
focus is the get the solution a bit more robust (so it can be used with any
device) and upstream it to rust-vmm space on github.

> With Xen grant mappings, if I am not mistaken, it is going to be almost the
> same: mmap() then ioctl(). But the file will be "/dev/xen/gntdev".

Okay, the problem (for us) still exists then :)
 
> FYI, new branch "virtio_grant" besides supporting Xen grant mappings also
> supports virtio-mmio modern transport.

Somehow the timing of your emails have been spot on.

Last time, when you told me about the "dev" branch, I have already started to
reinvent the wheel and your branch really helped.

Now, it was just yesterday that I started looking into MMIO modern stuff as the
GPIO device needs it and you sent me working code to look how to do it as well.
You saved at least 1-2 days of my time :)

Thanks Oleksandr.

-- 
viresh