RE: [PATCH v4 06/15] iommu/vt-d: Support setting ioasid set to domain

[Liu, Yi L]

Hi Eric,

> From: Auger Eric <eric.auger@xxxxxxxxxx>
> Sent: Monday, July 6, 2020 10:52 PM
> 
> Hi Yi,
> 
> On 7/4/20 1:26 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.
> >
> > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > Cc: Eric Auger <eric.auger@xxxxxxxxxx>
> > Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> > Cc: Joerg Roedel <joro@xxxxxxxxxx>
> > Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/iommu/intel/iommu.c | 16 ++++++++++++++++
> >  include/linux/intel-iommu.h |  4 ++++
> >  include/linux/iommu.h       |  1 +
> >  3 files changed, 21 insertions(+)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 62ebe01..89d708d 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 +6040,21 @@ intel_iommu_domain_set_attr(struct iommu_domain
> *domain,
> >  		}
> >  		spin_unlock_irqrestore(&device_domain_lock, flags);
> >  		break;
> > +	case DOMAIN_ATTR_IOASID_SID:
> no need to take the device_domain_lock?

oh, yes. thanks for spotting it.

> > +		if (!(dmar_domain->flags & DOMAIN_FLAG_NESTING_MODE)) {
> > +			ret = -ENODEV;
> > +			break;
> > +		}
> > +		if ((dmar_domain->ioasid_sid != INVALID_IOASID_SET) &&
> > +		    (dmar_domain->ioasid_sid != (*(int *) data))) {
> storing *(int *) data) in a local variable would increase the
> readability of the code I think.

will do it. :-)

Regards,
Yi Liu

> > +			pr_warn_ratelimited("multi ioasid_set (%d:%d) setting",
> > +					    dmar_domain->ioasid_sid,
> > +					    (*(int *) data));
> > +			ret = -EBUSY;
> > +			break;
> > +		}
> > +		dmar_domain->ioasid_sid = *(int *) data;
> > +		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 2567c33..21d32be 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,
> >  };
> >
> >
> Thanks
> 
> Eric