linux-kernel - Re: [PATCH v2 2/5] iommu: Introduce mm_get

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Message-ID: <ZPDHwseKQ3IC8dT9@ziepe.ca>
Date:   Thu, 31 Aug 2023 14:02:58 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Baolu Lu <baolu.lu@...ux.intel.com>
Cc:     Tina Zhang <tina.zhang@...el.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Michael Shavit <mshavit@...gle.com>, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/5] iommu: Introduce mm_get_pasid() helper function

On Thu, Aug 31, 2023 at 01:14:20PM +0800, Baolu Lu wrote:
> On 2023/8/27 16:43, Tina Zhang wrote:
> > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> > index e95b339e9cdc0..e6377cff6a935 100644
> > --- a/drivers/iommu/intel/svm.c
> > +++ b/drivers/iommu/intel/svm.c
> > @@ -306,13 +306,13 @@ static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
> >   	unsigned long sflags;
> >   	int ret = 0;
> > -	svm = pasid_private_find(mm->pasid);
> > +	svm = pasid_private_find(mm_get_pasid(mm));
> >   	if (!svm) {
> >   		svm = kzalloc(sizeof(*svm), GFP_KERNEL);
> >   		if (!svm)
> >   			return -ENOMEM;
> > -		svm->pasid = mm->pasid;
> > +		svm->pasid = mm_get_pasid(mm);
> >   		svm->mm = mm;
> >   		INIT_LIST_HEAD_RCU(&svm->devs);
> > @@ -350,7 +350,7 @@ static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
> >   	/* Setup the pasid table: */
> >   	sflags = cpu_feature_enabled(X86_FEATURE_LA57) ? PASID_FLAG_FL5LP : 0;
> > -	ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, mm->pasid,
> > +	ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, mm_get_pasid(mm),
> >   					    FLPT_DEFAULT_DID, sflags);
> >   	if (ret)
> >   		goto free_sdev;
> > @@ -364,7 +364,7 @@ static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
> >   free_svm:
> >   	if (list_empty(&svm->devs)) {
> >   		mmu_notifier_unregister(&svm->notifier, mm);
> > -		pasid_private_remove(mm->pasid);
> > +		pasid_private_remove(mm_get_pasid(mm));
> >   		kfree(svm);
> >   	}
> 
> There is no need to use mm_get_pasid(mm) in the set_dev_pasid path. The
> pasid has already passed as a parameter. Perhaps, pass domain and pasid
> to intel_svm_bind_mm(), or simply merge intel_svm_bind_mm() to
> intel_svm_set_dev_pasid()?
> 
> Something like below?

Yes please! As a prep patch 'remove mm->pasid references from vt-d'

Jason