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Date:   Fri, 23 Sep 2022 10:07:21 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Baolu Lu <baolu.lu@linux.intel.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Christoph Hellwig <hch@infradead.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Vinod Koul <vkoul@kernel.org>,
        Eric Auger <eric.auger@redhat.com>,
        Liu Yi L <yi.l.liu@intel.com>,
        Jacob jun Pan <jacob.jun.pan@intel.com>,
        Zhangfei Gao <zhangfei.gao@linaro.org>,
        Zhu Tony <tony.zhu@intel.com>, iommu@lists.linux.dev,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v13 07/13] iommu/vt-d: Add SVA domain support
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On Fri, Sep 23, 2022 at 08:41:56PM +0800, Baolu Lu wrote:
> On 2022/9/23 20:15, Jason Gunthorpe wrote:
> > On Fri, Sep 23, 2022 at 10:21:51AM +0800, Baolu Lu wrote:
> > 
> > > At the beginning of this project, I wanted to consolidate the mm
> > > notifications into the core. However, ARM SMMUv3 and Intel handle the mm
> > > notifications a little differently. Then I decided to do this work
> > > separately from the current series.
> > 
> > It doesn't look really different..
> 
> They are essentially the same, but slightly different. For example, arm
> smmuv3 provides .free_notifier, and I don't think it could be merged to
> the release callback.

free_notifier allows to use mmu_notifier_put() instead of
mmu_notifier_unregister() which avoids a synchronize_rcu() penalty on
teardown. Intel should copy the same design.

Jason