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

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Message-ID: <d5c4181f-4542-e8bc-adb6-35eb3d8f5b21@redhat.com>
Date:   Thu, 16 Apr 2020 12:46:07 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.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>
Subject: Re: [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support

Hi Jacob,

On 4/10/20 11:06 PM, Jacob Pan wrote:
> 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"
ok sorry
> 
>>> +				 * 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.
ok

Thanks

Eric
> 
> 
> Thanks,
> 
> Jacob
>