RE: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper

Shameerali Kolothum Thodi
2023-03-16T19:57:43Z

> -----Original Message-----
> From: Nicolin Chen [mailto:nicolinc@nvidia.com]
> Sent: 16 March 2023 19:51
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> Eric Auger <eric.auger@redhat.com>
> Cc: Jason Gunthorpe <jgg@nvidia.com>; robin.murphy@arm.com;
> will@kernel.org; kevin.tian@intel.com; baolu.lu@linux.intel.com;
> joro@8bytes.org; jean-philippe@linaro.org;
> linux-arm-kernel@lists.infradead.org; iommu@lists.linux.dev;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain
> helper
>
> Hi Shameer/Eric,
>
> On Fri, Mar 10, 2023 at 04:30:03PM +0000, Shameerali Kolothum Thodi
> wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > > -----Original Message-----
> > > From: Jason Gunthorpe [mailto:jgg@nvidia.com]
> > > Sent: 10 March 2023 16:21
> > > To: Shameerali Kolothum Thodi
> <shameerali.kolothum.thodi@huawei.com>
> > > Cc: Eric Auger <eric.auger@redhat.com>; Nicolin Chen
> > > <nicolinc@nvidia.com>; robin.murphy@arm.com; will@kernel.org;
> > > kevin.tian@intel.com; baolu.lu@linux.intel.com; joro@8bytes.org;
> > > jean-philippe@linaro.org; linux-arm-kernel@lists.infradead.org;
> > > iommu@lists.linux.dev; linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH v1 01/14] iommu: Add
> iommu_get_unmanaged_domain
> > > helper
> > >
> > > On Fri, Mar 10, 2023 at 04:07:38PM +0000, Shameerali Kolothum Thodi
> > > wrote:
> > > > >
> > >
> https://lore.kernel.org/linux-arm-kernel/20220420164836.1181-5-shame
> > > er
> > > > > > ali.kolothum.thodi@huawei.com/
> > > > >
> > > > > So "boot configration" is more like "don't change the RIDs"? Ie
> > > > > don't
> > > enable
> > > > > SRIOV?
> > > >
> > > > Yes. Don't think it will work with SR-IOV if you can't guarantee
> > > > the RMR
> > > specified
> > > > SID.
> > >
> > > So I think we are probably good them because vSR-IOV is already not
> > > supported by qemu, so it impossible for a VM to change the PCI
> > > configuration in a way that would alter the RID to SID mapping?
> > >
> >
> > Provided we fix the issue mentioned by Eric. This was discussed here
> > previously,
> >
> > https://lore.kernel.org/linux-arm-kernel/bb3688c7-8f42-039e-e22f-65290
> > 78da97d@redhat.com/
>
> Have we fixed the issue? I saw Lorenzo replying in that thread:
> https://lore.kernel.org/linux-arm-kernel/Yi8nV8H4Jjlpadmk@lpieralisi/
>
> Or, what's remaining here regarding this topic? Is it a blocker?

[+Lorenzo]

Not sure it is fixed yet. Also, assuming we take RMR path, do we plan to support
DT base Guests at all?

Thanks,
Shameer