Re: [PATCH v2 00/33] iommu: Move iommu_group setup to IOMMU core code

[Jerry Snitselaar]

On Tue Jun 02 20, Lu Baolu wrote:
> Hi Jerry,
>
> On 6/1/20 6:42 PM, Jerry Snitselaar wrote:
> > > Hi Joerg,
> > >
> > > With this patchset, I have an epyc system where if I boot with
> > > iommu=nopt and force a dump I will see some io page faults for a nic
> > > on the system. The vmcore is harvested and the system reboots. I
> > > haven't reproduced it on other systems yet, but without the patchset I
> > > don't see the io page faults during the kdump.
> > >
> > > Regards,
> > > Jerry
> >
> > I just hit an issue on a separate intel based system (kdump iommu=nopt),
> > where it panics in during intel_iommu_attach_device, in is_aux_domain,
> > due to device_domain_info being DEFER_DEVICE_DOMAIN_INFO. That doesn't
> > get set to a valid address until the domain_add_dev_info call.
> >
> > Is it as simple as the following?
>
> I guess you won't hit this issue if you use iommu/next branch of Joerg's
> tree. We've changed to use a generic helper to retrieve the valid per
> device iommu data or NULL (if there's no).
>
> Best regards,
> baolu

Yeah, that will solve the panic. 

> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index 29d3940847d3..f1bbeed46a4c 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -5053,8 +5053,8 @@ is_aux_domain(struct device *dev, struct 
> > iommu_domain *domain)
> > Â{
> > ÂÂÂÂÂÂÂ struct device_domain_info *info = dev->archdata.iommu;
> >
> > -ÂÂÂÂÂÂ return info && info->auxd_enabled &&
> > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ domain->type == IOMMU_DOMAIN_UNMANAGED;
> > +ÂÂÂÂÂÂ return info && info != DEFER_DEVICE_DOMAIN_INFO &&
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ info->auxd_enabled && domain->type == 
> > IOMMU_DOMAIN_UNMANAGED;
> > Â}
> >
> > Âstatic void auxiliary_link_device(struct dmar_domain *domain,
> >
> >
> > Regards,
> > Jerry
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