linux-kernel - Re: [PATCH 1/2] iommu/vt-d: Use rbtree to track iommu probed devices

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Message-ID: <942dd645-7475-4c43-99c6-304601fb09eb@linux.intel.com>
Date: Mon, 19 Feb 2024 12:04:56 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Ethan Zhao <haifeng.zhao@...ux.intel.com>, Joerg Roedel
 <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Jason Gunthorpe <jgg@...pe.ca>,
 Kevin Tian <kevin.tian@...el.com>
Cc: baolu.lu@...ux.intel.com, Huang Jiaqing <jiaqing.huang@...el.com>,
 iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] iommu/vt-d: Use rbtree to track iommu probed devices

On 2024/2/19 10:45, Ethan Zhao wrote:
>> @@ -4264,25 +4313,34 @@ static struct iommu_device 
>> *intel_iommu_probe_device(struct device *dev)
>>       }
>>       dev_iommu_priv_set(dev, info);
>> +    ret = device_rbtree_insert(iommu, info);
>> +    if (ret)
>> +        goto free;
>>       if (sm_supported(iommu) && !dev_is_real_dma_subdevice(dev)) {
>>           ret = intel_pasid_alloc_table(dev);
>>           if (ret) {
>>               dev_err(dev, "PASID table allocation failed\n");
>> -            kfree(info);
>> -            return ERR_PTR(ret);
>> +            goto clear_rbtree;
>>           }
>>       }
>>       intel_iommu_debugfs_create_dev(info);
>>       return &iommu->iommu;
>> +clear_rbtree:
>> +    device_rbtree_remove(info);
>> +free:
>> +    kfree(info);
>> +
>> +    return ERR_PTR(ret);
>>   }
>>   static void intel_iommu_release_device(struct device *dev)
>>   {
>>       struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +    device_rbtree_remove(info);
> 
> Perhpas too early here to remove dev from the rbtree, if it is wanted in
> devTLB invalidation steps in intel_pasid_tear_down_entry().

Perhaps the caller of device_rbtree_find() should not depend on the
order in the release_device callback. For the device TLB invalidation
timed-out case, probably it could be checked in this way:

     struct device *dev = device_rbtree_find(iommu, ite_sid);
     if (!dev || !pci_device_is_present(to_pci_dev(dev)))
         return -ETIMEDOUT;

Best regards,
baolu