Re: [PATCH v4 3/6] iommu/vt-d: Implement domain ops for attach_dev_pasid

Jason Gunthorpe
2022-05-24T18:02:52Z

On Tue, May 24, 2022 at 09:12:35AM -0700, Jacob Pan wrote:
> Hi Jason,
>
> On Tue, 24 May 2022 10:51:35 -0300, Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> > On Wed, May 18, 2022 at 11:21:17AM -0700, Jacob Pan wrote:
> > > On VT-d platforms with scalable mode enabled, devices issue DMA requests
> > > with PASID need to attach PASIDs to given IOMMU domains. The attach
> > > operation involves the following:
> > > - Programming the PASID into the device's PASID table
> > > - Tracking device domain and the PASID relationship
> > > - Managing IOTLB and device TLB invalidations
> > >
> > > This patch add attach_dev_pasid functions to the default domain ops
> > > which is used by DMA and identity domain types. It could be extended to
> > > support other domain types whenever necessary.
> > >
> > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > drivers/iommu/intel/iommu.c | 72 +++++++++++++++++++++++++++++++++++--
> > > 1 file changed, 70 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > > index 1c2c92b657c7..75615c105fdf 100644
> > > +++ b/drivers/iommu/intel/iommu.c
> > > @@ -1556,12 +1556,18 @@ static void __iommu_flush_dev_iotlb(struct
> > > device_domain_info *info, u64 addr, unsigned int mask)
> > > {
> > > u16 sid, qdep;
> > > + ioasid_t pasid;
> > >
> > > if (!info || !info->ats_enabled)
> > > return;
> > >
> > > sid = info->bus << 8 | info->devfn;
> > > qdep = info->ats_qdep;
> > > + pasid = iommu_get_pasid_from_domain(info->dev,
> > > &info->domain->domain);
> >
> > No, a simgple domain can be attached to multiple pasids, all need to
> > be flushed.
> >
> Here is device TLB flush, why would I want to flush PASIDs other than my
> own device attached?

Again, a domain can be attached to multiple PASID's *on the same
device*

The idea that there is only one PASID per domain per device is not
right.

Jason