XFS, stable kernels, and -rc releases

Posted Dec 4, 2020 17:00 UTC (Fri) by sashal (✭ supporter ✭, #81842)
In reply to: XFS, stable kernels, and -rc releases by pbonzini
Parent article: XFS, stable kernels, and -rc releases

So I'm curious, I got pinged last month asking me to add a patch that seemed to be able to cause a host hang (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/...) which also had a CVE id attached to it.

Why didn't it have a stable tag? Or not sent to us from the KVM maintainers?

XFS, stable kernels, and -rc releases

Posted Dec 4, 2020 17:17 UTC (Fri) by pbonzini (subscriber, #60935) [Link] (4 responses)

- Because it cannot happen with SR-IOV devices; passthrough of non-SR-IOV devices is simply not used in circumstances where a host hang can have security consequences, while hobbyists that do use it (e.g. for gaming) tend to stay on bleeding edge kernels.

- It has an easy workaround in userspace.

So I considered it as a minor bug even though it has a CVE id attached.

XFS, stable kernels, and -rc releases

Posted Dec 4, 2020 17:55 UTC (Fri) by sashal (✭ supporter ✭, #81842) [Link] (3 responses)

I think that your assumptions around who does GPU passthrough are a bit off :)

XFS, stable kernels, and -rc releases

Posted Dec 4, 2020 18:54 UTC (Fri) by pbonzini (subscriber, #60935) [Link] (2 responses)

Mediated pass-through aka vGPU is very different from PCI pass-through that you do for gaming.

XFS, stable kernels, and -rc releases

Posted Dec 4, 2020 20:39 UTC (Fri) by zdzichu (subscriber, #17118) [Link] (1 responses)

And which one do you do for cryptocurrencies mining and machine learning?

XFS, stable kernels, and -rc releases

Posted Dec 4, 2020 22:06 UTC (Fri) by pbonzini (subscriber, #60935) [Link]

For Tesla you do mediated pass-through. Consumer hardware only does PCI pass-through (as far as I know that's just driver-enforced market segmentation, but still).