RE: [PATCH v5 06/15] iommu/vt-d: Support setting ioasid set to domain

Liu, Yi L
2020-07-20T08:11:24Z

Hi Eric,

> From: Auger Eric <eric.auger@redhat.com>
> Sent: Sunday, July 19, 2020 11:38 PM
>
> Yi,
>
> On 7/12/20 1:21 PM, Liu Yi L wrote:
> > From IOMMU p.o.v., PASIDs allocated and managed by external components
> > (e.g. VFIO) will be passed in for gpasid_bind/unbind operation. IOMMU
> > needs some knowledge to check the PASID ownership, hence add an
> > interface for those components to tell the PASID owner.
> >
> > In latest kernel design, PASID ownership is managed by IOASID set
> > where the PASID is allocated from. This patch adds support for setting
> > ioasid set ID to the domains used for nesting/vSVA. Subsequent SVA
> > operations on the PASID will be checked against its IOASID set for proper
> ownership.
> Subsequent SVA operations will check the PASID against its IOASID set for proper
> ownership.

got it.

> >
> > Cc: Kevin Tian <kevin.tian@intel.com>
> > CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Eric Auger <eric.auger@redhat.com>
> > Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > ---
> > v4 -> v5:
> > *) address comments from Eric Auger.
> > ---
> > drivers/iommu/intel/iommu.c | 22 ++++++++++++++++++++++
> > include/linux/intel-iommu.h | 4 ++++
> > include/linux/iommu.h | 1 +
> > 3 files changed, 27 insertions(+)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 72ae6a2..4d54198 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -1793,6 +1793,7 @@ static struct dmar_domain *alloc_domain(int flags)
> > if (first_level_by_default())
> > domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;
> > domain->has_iotlb_device = false;
> > + domain->ioasid_sid = INVALID_IOASID_SET;
> > INIT_LIST_HEAD(&domain->devices);
> >
> > return domain;
> > @@ -6039,6 +6040,27 @@ intel_iommu_domain_set_attr(struct iommu_domain
> *domain,
> > }
> > spin_unlock_irqrestore(&device_domain_lock, flags);
> > break;
> > + case DOMAIN_ATTR_IOASID_SID:
> > + {
> > + int sid = *(int *)data;
> > +
> > + if (!(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE)) {
> > + ret = -ENODEV;
> > + break;
> > + }
> > + spin_lock_irqsave(&device_domain_lock, flags);
> I think the lock should be taken before the DOMAIN_FLAG_NESTING_MODE check.
> Otherwise, the flags can be theretically changed inbetween the check and the test
> below?

I see. will correct it.

Thanks,
Yi Liu

> Thanks
>
> Eric
> > + if (dmar_domain->ioasid_sid != INVALID_IOASID_SET &&
> > + dmar_domain->ioasid_sid != sid) {
> > + pr_warn_ratelimited("multi ioasid_set (%d:%d) setting",
> > + dmar_domain->ioasid_sid, sid);
> > + ret = -EBUSY;
> > + spin_unlock_irqrestore(&device_domain_lock, flags);
> > + break;
> > + }
> > + dmar_domain->ioasid_sid = sid;
> > + spin_unlock_irqrestore(&device_domain_lock, flags);
> > + break;
> > + }
> > default:
> > ret = -EINVAL;
> > break;
> > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> > index 3f23c26..0d0ab32 100644
> > --- a/include/linux/intel-iommu.h
> > +++ b/include/linux/intel-iommu.h
> > @@ -549,6 +549,10 @@ struct dmar_domain {
> > 2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
> > u64 max_addr; /* maximum mapped address */
> >
> > + int ioasid_sid; /*
> > + * the ioasid set which tracks all
> > + * PASIDs used by the domain.
> > + */
> > int default_pasid; /*
> > * The default pasid used for non-SVM
> > * traffic on mediated devices.
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h index
> > 7ca9d48..e84a1d5 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -124,6 +124,7 @@ enum iommu_attr {
> > DOMAIN_ATTR_FSL_PAMUV1,
> > DOMAIN_ATTR_NESTING, /* two stages of translation */
> > DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
> > + DOMAIN_ATTR_IOASID_SID,
> > DOMAIN_ATTR_MAX,
> > };
> >
> >