[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH v2] intel_iommu: check misordered init when real

From: Marcel Apfelbaum
Subject: Re: [Qemu-devel] [PATCH v2] intel_iommu: check misordered init when realize
Date: Wed, 1 Mar 2017 11:29:47 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1

On 03/01/2017 11:18 AM, Peter Xu wrote:
On Wed, Mar 01, 2017 at 09:03:47AM +0200, Marcel Apfelbaum wrote:
On 03/01/2017 06:14 AM, Jason Wang wrote:


Hi Jason,

I am not saying we don't need to create the IOMMU before some other device,
I just don't think that the command line order should matter to user.

BTW, are you working on a way to limit the IOMMU scope to a specific set of 
If yes, this approach will also help you work.


Do you have any plan after 2.9 to re-arrange the init order thing a
bit? In general, maybe we need an ordering support for devices.

I don;t know when I'll start it, but yes, I am thinking about
taking this project. We need the ordering in order to be able
to have less "built-in" devices.

Besides that, I am thinking whether it would be wise that we just init
the IOMMUs during machine init just like before, but keep the
"-device" interface? After all, at least the root IOMMU device should
be with root complex, and it feels a little strange we just split the
init process apart (we delay the IOMMU init into device

Keeping the IOMMU creation as part of the Root Complex is problematic.
What happens if we want to limit the IOMMU scope to a subset of devices?
How will the command line look? Also we may want/need multiple iommu
devices per system. It will not happen tomorrow, but we don't want to loose
this possibility.

The device re-ordering is not 2.9 material of course, and we need your patch.
The only thing we can do better is to take out the "vfio-pci" in another header
file and and have it in a array of devices that should be checked
(in order to avoid polluting the IOMMU code with a not related device)

I can try and send a patch for it if you prefer.


Not sure whether above makes sense though. Thanks,

-- peterx

reply via email to

[Prev in Thread] Current Thread [Next in Thread]