linux-kernel - Re: [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support

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Date:   Fri, 10 Apr 2020 14:06:04 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Auger Eric <eric.auger@...hat.com>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Yi L <yi.l.liu@...ux.intel.com>, jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support

Hi Eric,

Missed a few things in the last reply.

On Thu, 9 Apr 2020 09:41:32 +0200
Auger Eric <eric.auger@...hat.com> wrote:

> > +			intel_pasid_tear_down_entry(iommu, dev,
> > svm->pasid);  
> intel_svm_unbind_mm() calls intel_flush_svm_range_dev(svm, sdev, 0,
> -1, 0); Don't we need to flush the (DEV-)IOTLBs as well?
Right, pasid tear down should always include (DEV-)IOTLB flush, I
initially thought it is taken care of by intel_pasid_tear_down_entry().

> > +			/* TODO: Drain in flight PRQ for the PASID
> > since it
> > +			 * may get reused soon, we don't want to
> > +			 * confuse with its previous life.
> > +			 * intel_svm_drain_prq(dev, pasid);
> > +			 */
> > +			kfree_rcu(sdev, rcu);
> > +
> > +			if (list_empty(&svm->devs)) {
> > +				/*
> > +				 * We do not free the IOASID here
> > in that
> > +				 * IOMMU driver did not allocate
> > it.  
> s/in/as?
I meant to say "in that" as "for the reason that"

> > +				 * Unlike native SVM, IOASID for
> > guest use was
> > +				 * allocated prior to the bind
> > call.> +				 * In any case, if the free
> > call comes before
> > +				 * the unbind, IOMMU driver will
> > get notified
> > +				 * and perform cleanup.
> > +				 */
> > +				ioasid_set_data(pasid, NULL);
> > +				kfree(svm);
> > +			}  
> nit: you may use intel_svm_free_if_empty()
True, but I meant to insert ioasid_notifier under the list_empty
condition in the following ioasid patch.


Thanks,

Jacob