Received-SPF: pass (google.com: domain of linux-kernel+bounces-74210-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Message-ID: <e77922a5-89d3-4036-8d98-9c3fbef4f39c@linux.intel.com>
Date: Wed, 21 Feb 2024 15:21:12 +0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Cc: baolu.lu@linux.intel.com, "iommu@lists.linux.dev"
 <iommu@lists.linux.dev>,
 "virtualization@lists.linux-foundation.org"
 <virtualization@lists.linux-foundation.org>,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/8] iommu: Add iopf domain attach/detach/replace
 interface
Content-Language: en-US
To: "Tian, Kevin" <kevin.tian@intel.com>, Jason Gunthorpe <jgg@ziepe.ca>,
 Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
 Robin Murphy <robin.murphy@arm.com>,
 Jean-Philippe Brucker <jean-philippe@linaro.org>,
 Nicolin Chen <nicolinc@nvidia.com>, "Liu, Yi L" <yi.l.liu@intel.com>,
 Jacob Pan <jacob.jun.pan@linux.intel.com>,
 Joel Granados <j.granados@samsung.com>
References: <20240122073903.24406-1-baolu.lu@linux.intel.com>
 <20240122073903.24406-2-baolu.lu@linux.intel.com>
 <BN9PR11MB527629BF9A0E27E36D3925B18C452@BN9PR11MB5276.namprd11.prod.outlook.com>
 <b0f5e418-8faa-45d1-b086-61f6c009c0cb@linux.intel.com>
 <BN9PR11MB5276151E34AC91883986A39D8C572@BN9PR11MB5276.namprd11.prod.outlook.com>
From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <BN9PR11MB5276151E34AC91883986A39D8C572@BN9PR11MB5276.namprd11.prod.outlook.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

On 2024/2/21 14:49, Tian, Kevin wrote:
>>>> +struct iopf_attach_cookie {
>>>> +	struct iommu_domain *domain;
>>>> +	struct device *dev;
>>>> +	unsigned int pasid;
>>>> +	refcount_t users;
>>>> +
>>>> +	void *private;
>>>> +	void (*release)(struct iopf_attach_cookie *cookie);
>>>> +};
>>> this cookie has nothing specific to iopf.
>>>
>>> it may makes more sense to build a generic iommu_attach_device_cookie()
>>> helper so the same object can be reused in future other usages too.
>>>
>>> within iommu core it can check domain iopf handler and this generic cookie
>>> to update iopf specific data e.g. the pasid_cookie xarray.
>> This means attaching an iopf-capable domain follows two steps:
>>
>> 1) Attaching the domain to the device.
>> 2) Setting up the iopf data, necessary for handling iopf data.
>>
>> This creates a time window during which the iopf is enabled, but the
>> software cannot handle it. Or not?
>>
> why two steps? in attach you can setup the iopf data when recognizing
> that the domain is iopf capable...

Oh, maybe I misunderstood. So your proposal is to make the new interface
generic, not for iopf only?

Best regards,
baolu