Re: [Xen-devel] [PATCH] amd iommu: re-enable iommu msi if dom0 disabled it

[Wei Wang <wei.wang2@xxxxxxx>]

On 06/08/2012 03:31 PM, Andrew Cooper wrote:
> On 08/06/12 14:28, Wei Wang wrote:
> > Hi Jan,
> > I found that recent dom0 (e.g 3.4 pv_ops) disables iommu msi capability
> > for some reasons and iommu cannot generate any interrupts in this case.
> > Attached patch re-enables it in device assignment.
> Under which circumstances should dom0 able to play with the IOMMUs ?
> Surely the fact that dom0 can play with the IOMMUs is a bug in itself.
It looks like some generic msi/pci codes disable it, not the Linux iommu 
driver itself, which is only loaded on bare metal. AMD IOMMU expose 
interrupt capability as a normal msi block. So the general pci/msi layer 
of dom0 might touch it...
Thanks,
Wei


> > Thanks,
> > Wei
> >
> > --
> > Advanced Micro Devices GmbH
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> > Landkreis München Registergericht München,
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> > Alberto Bozzo


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