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Date:   Fri, 23 Sep 2022 20:41:56 +0800
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Cc:     baolu.lu@linux.intel.com, 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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To:     Jason Gunthorpe <jgg@nvidia.com>
References: <20220906124458.46461-1-baolu.lu@linux.intel.com>
 <20220906124458.46461-8-baolu.lu@linux.intel.com>
 <YyyECCbmfsaDpDgJ@nvidia.com>
 <075278e0-77ce-2361-8ded-6cd6bb20216f@linux.intel.com>
 <Yy2jbsaXuoxgR+fj@nvidia.com>
From:   Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <Yy2jbsaXuoxgR+fj@nvidia.com>
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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.

> 
> The SVA iommu domain needs two new ops triggered by the notifier:
> 
>   - 'stop using the mm, subsitute a blocking domain' tied to release
>   - Cache invalidate a range, maybe this is just iotlb_sync_map()
> 
> And we could even think about the first as the core code literally
> attaching a dummy blocking domain and releasing the SVA domain. There
> is no reason we need to have every driver do this tricky bit of
> lifecycle management.

Yes. I have similar ideas. We can further discuss it with the real code
later.

Best regards,
baolu