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Date:   Mon, 25 Jul 2022 18:11:13 +0800
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Cc:     baolu.lu@linux.intel.com, Joerg Roedel <joro@8bytes.org>,
        Christoph Hellwig <hch@infradead.org>,
        "Raj, Ashok" <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        Vinod Koul <vkoul@kernel.org>,
        Eric Auger <eric.auger@redhat.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "Pan, Jacob jun" <jacob.jun.pan@intel.com>,
        Zhangfei Gao <zhangfei.gao@linaro.org>,
        "Zhu, Tony" <tony.zhu@intel.com>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>
Subject: Re: [PATCH v10 04/12] iommu: Add attach/detach_dev_pasid iommu
 interface
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To:     "Tian, Kevin" <kevin.tian@intel.com>,
        Jason Gunthorpe <jgg@nvidia.com>
References: <20220705050710.2887204-1-baolu.lu@linux.intel.com>
 <20220705050710.2887204-5-baolu.lu@linux.intel.com>
 <20220723141118.GD79279@nvidia.com>
 <5d353fe4-b642-992e-ef42-7d7f8b2edf7e@linux.intel.com>
 <BN9PR11MB527627410352E6DE921755898C959@BN9PR11MB5276.namprd11.prod.outlook.com>
From:   Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <BN9PR11MB527627410352E6DE921755898C959@BN9PR11MB5276.namprd11.prod.outlook.com>
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On 2022/7/25 15:46, Tian, Kevin wrote:
>> From: Baolu Lu <baolu.lu@linux.intel.com>
>> Sent: Sunday, July 24, 2022 5:14 PM
>>
>> On 2022/7/23 22:11, Jason Gunthorpe wrote:
>>>> +void iommu_detach_device_pasid(struct iommu_domain *domain,
>> struct device *dev,
>>>> +			       ioasid_t pasid)
>>>> +{
>>>> +	struct iommu_group *group = iommu_group_get(dev);
>>>> +
>>>> +	mutex_lock(&group->mutex);
>>>> +	domain->ops->block_dev_pasid(domain, dev, pasid);
>>> I still really this OP, it is nonsense to invoke 'block_dev_pasid' on
>>> a domain, it should be on the iommu ops and it should not take in a
>>> domain parameter. This is why I prefer we write it as
>>>
>>> domain->ops->set_dev_pasid(group->blocking_domain, dev, pasid);
>>>
>>
>> I originally plan to refactor this after both Intel and ARM SMMUv3
>> drivers have real blocking domain supports. After revisiting this, it
>> seems that the only difficulty is how to check whether a domain is a
>> blocking domain. I am going to use below checking code:
>>
>> +	/*
>> +	 * Detach the domain if a blocking domain is set. Check the
>> +	 * right domain type once the IOMMU driver supports a real
>> +	 * blocking domain.
>> +	 */
>> +	if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
>>
>> Does this work for you?
>>
> 
> Or you can call __iommu_group_alloc_blocking_domain() in the sva
> path and then just check whether the domain is equal to
> group->blocking_domain here.

Above check is in the IOMMU driver where group->blocking_domain is not
viable. I ever thought about have something like

struct iommu_domain *iommu_group_blocking_domain(struct iommu_group
*group)

to return group->blocking_domain. But it looks redundant.

Best regards,
baolu