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Date:   Fri, 6 May 2022 13:36:37 +0800
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Subject: Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID
 allocation and free it on mm exit
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To:     Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc:     Fenghua Yu <fenghua.yu@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Ashok Raj <ashok.raj@intel.com>,
        Ravi V Shankar <ravi.v.shankar@intel.com>,
        Peter Zijlstra <peterz@infradead.org>, robin.murphy@arm.com,
        Dave Hansen <dave.hansen@linux.intel.com>,
        x86 <x86@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        iommu <iommu@lists.linux-foundation.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>, zhangfei.gao@linaro.org,
        Thomas Gleixner <tglx@linutronix.de>, will@kernel.org
References: <YmbO/l5IwfBCHrl8@myrica>
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From:   Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <YnDeoGjv/dZnu+YQ@myrica>
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On 2022/5/3 15:49, Jean-Philippe Brucker wrote:
> On Sat, Apr 30, 2022 at 03:33:17PM +0800, Baolu Lu wrote:
>> Jean, another quick question about the iommu_sva_bind_device()
>>
>> /**
>>   * iommu_sva_bind_device() - Bind a process address space to a device
>>   * @dev: the device
>>   * @mm: the mm to bind, caller must hold a reference to it
>>   * @drvdata: opaque data pointer to pass to bind callback
>>
>> This interface requires the caller to take a reference to mm. Which
>> reference should it take, mm->mm_count or mm->mm_users? It's better to
>> make it explicit in this comment.
> 
> Agreed, it's mm_users as required by mmu_notifier_register()

Thanks! I will add this in my refactoring patch.

Best regards,
baolu