Re: [Qemu-devel] [PATCH] intel_iommu: fix VTD_SID_TO_BUS

[Knut Omang]

On Mon, 2014-10-20 at 17:23 +0300, Michael S. Tsirkin wrote:
> WRT intel_iommu, it does not yet seem to be as fully functional as I
> hoped.  People also discussed the best way to handle virtio versus iommu
> (it bypasses it ATM).
> I'd like to suggest we hide the iommu from the command line
> help for 2.2, this way people don't activate it mistakenly.
> 
> Let's make it more complete and then enable for 2.3.
> 
> Thoughts?

Note that you have to explicitly enable iommu support in the guest
(intel_iommu=on on the boot command line in the Linux case) for it to
have any effect apart from being visible in the DMAR table and logging
so it should not really do any harm.

>From my perspective the feature works well and I have been running a few
virtual machines with div.network workload stable using the additional 4
patches referred to in this post (Jan's two for interrupt remapping and
two bug fixes and enhancements from me for running behind bridges) :

https://lists.nongnu.org/archive/html/qemu-devel/2014-08/msg02986.html

Latest version here:

https://github.com/knuto/qemu/tree/sriov_patches_v2

Give me a hint and I can rebase and post the two iommu patches, I
believe Jan wanted to do some more work on the interrupt remapping
first.

Knut