linux-kernel - Re: [PATCH 01/12] iommu/vt-d: Add cache tag assignment interface

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Message-ID: <ae40a717-5a16-4872-a4fd-69c792905a0e@linux.intel.com>
Date: Sun, 7 Apr 2024 12:35:01 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: "Tian, Kevin" <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Jason Gunthorpe <jgg@...pe.ca>
Cc: baolu.lu@...ux.intel.com, "Zhang, Tina" <tina.zhang@...el.com>,
 "Liu, Yi L" <yi.l.liu@...el.com>,
 "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/12] iommu/vt-d: Add cache tag assignment interface

On 4/6/24 8:55 PM, Baolu Lu wrote:
>>
>>> @@ -4607,10 +4623,11 @@ static void
>>> intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
>>>        */
>>>       if (domain->type == IOMMU_DOMAIN_SVA) {
>>>           intel_svm_remove_dev_pasid(dev, pasid);
>>> +        cache_tag_unassign_domain(dmar_domain,
>>> +                      FLPT_DEFAULT_DID, dev, pasid);
>>
>> is it correct to destroy the tag before teardown completes, e.g. iotlb 
>> still
>> needs to be flushed in intel_pasid_tear_down_entry()?
> 
> You are right. iotlb still needs to be there until the teardown
> completes. I will investigate this more later.

I reviewed this again. Cache tags are designed specifically for mapping
and unmapping paths. Therefore, there is no required order for attaching
and detaching paths.

Best regards,
baolu