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SubjectRe: [PATCH v5 8/8] iommu/vt-d: Misc macro clean up for SVM
On Mon, 02 Dec 2019 12:10:45 -0800
Joe Perches <joe@perches.com> wrote:

> On Mon, 2019-12-02 at 11:58 -0800, Jacob Pan wrote:
> > Use combined macros for_each_svm_dev() to simplify SVM device
> > iteration and error checking.
> []
> > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> []
> > @@ -427,40 +430,36 @@ int intel_svm_unbind_mm(struct device *dev,
> > int pasid)
> []
> > + for_each_svm_dev(sdev, svm, dev) {
> > + ret = 0;
> > + sdev->users--;
> > + if (!sdev->users) {
>
> This might be better by reducing indentation here too
>
> if (sdev->users)
> break;
>
> > + list_del_rcu(&sdev->list);
>
> to reduce indentation 1 level below this
Sounds good but perhaps we can do this in a separate patch.

>
> > + /* Flush the PASID cache and IOTLB for
> > this device.
> > + * Note that we do depend on the hardware
> > *not* using
> > + * the PASID any more. Just as we depend
> > on other
> > + * devices never using PASIDs that they
> > have no right
> > + * to use. We have a *shared* PASID table,
> > because it's
> > + * large and has to be physically
> > contiguous. So it's
> > + * hard to be as defensive as we might
> > like. */
> > + intel_pasid_tear_down_entry(iommu, dev,
> > svm->pasid);
> > + intel_flush_svm_range_dev(svm, sdev, 0,
> > -1, 0);
> > + kfree_rcu(sdev, rcu);
> > +
> > + if (list_empty(&svm->devs)) {
> > + ioasid_free(svm->pasid);
> > + if (svm->mm)
> > +
> > mmu_notifier_unregister(&svm->notifier, svm->mm);
> > + list_del(&svm->list);
> > + /* We mandate that no page faults
> > may be outstanding
> > + * for the PASID when
> > intel_svm_unbind_mm() is called.
> > + * If that is not obeyed, subtle
> > errors will happen.
> > + * Let's make them less subtle...
> > */
> > + memset(svm, 0x6b, sizeof(*svm));
> > + kfree(svm);
> > }
> > - break;
> > }
> > + break;
> > }
> > out:
> > mutex_unlock(&pasid_mutex);
>

[Jacob Pan]

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