RE: [PATCH v6 06/15] iommu/vt-d: Support setting ioasid set to domain

["Liu, Yi L" <yi.l.liu@intel.com>]

Hi Eric,

> From: Auger Eric <eric.auger@redhat.com>
> Sent: Thursday, August 13, 2020 11:07 PM
> 
> Hi Yi,
> 
> On 7/28/20 8:27 AM, 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 will check the PASID against its IOASID set for proper ownership.
> >
> > 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>
> > ---
> > v5 -> v6:
> > *) address comments against v5 from Eric Auger.
> >
> > v4 -> v5:
> > *) address comments from Eric Auger.
> > ---
> >  drivers/iommu/intel/iommu.c | 23 +++++++++++++++++++++++
> > include/linux/intel-iommu.h |  4 ++++
> >  include/linux/iommu.h       |  1 +
> >  3 files changed, 28 insertions(+)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index ed4b71c..b2fe54e 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;
> > @@ -6040,6 +6041,28 @@ 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;
> 
> > +
> > +		spin_lock_irqsave(&device_domain_lock, flags);
> > +		if (!(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE)) {
> > +			ret = -ENODEV;
> > +			spin_unlock_irqrestore(&device_domain_lock, flags);
> > +			break;
> > +		}
> > +		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;
> nit: Adding a small helper
> int__set_ioasid_sid(struct dmar_domain *dmar_domain, int sid_id)
> 
> may simplify the lock handling

ok. will do.

> 
> > +	}
> >  	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
> id of the ioasid set?

should be ioasid_set. however, ioasid_alloc_set() returns sid in Jacob's
series. but, I heard from Jacob, he will remove ioasid_sid, and return
ioasid_set. so I will modify it once his patch is sent out.

https://lore.kernel.org/linux-iommu/1585158931-1825-4-git-send-email-jacob.jun.pan@linux.intel.com/

> > +					 * 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
> > 4a02c9e..b1ff702 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,
> >  };
> >
> >
> Besides
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

thanks :-)

Regards,
Yi Liu

> 
> Eric

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