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Subject: Re: [RFC PATCH] iommu/vt-d: Fix IOMMU field not populated on device
 hot re-plug
To:     Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
References: <20190822142922.31526-1-janusz.krzysztofik@linux.intel.com>
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From:   Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <52fbfac9-c879-4b45-dd74-fafe62c2432b@linux.intel.com>
Date:   Tue, 3 Sep 2019 09:29:40 +0800
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Hi Janusz,

On 9/2/19 4:37 PM, Janusz Krzysztofik wrote:
>> I am not saying that keeping data is not acceptable. I just want to
>> check whether there are any other solutions.
> Then reverting 458b7c8e0dde and applying this patch still resolves the issue
> for me.  No errors appear when mappings are unmapped on device close after the
> device has been removed, and domain info preserved on device removal is
> successfully reused on device re-plug.

This patch doesn't look good to me although I agree that keeping data is
acceptable. It updates dev->archdata.iommu, but leaves the hardware
context/pasid table unchanged. This might cause problems somewhere.

> 
> Is there anything else I can do to help?

Can you please tell me how to reproduce the problem? Keeping the per
device domain info while device is unplugged is a bit dangerous because
info->dev might be a wild pointer. We need to work out a clean fix.

> 
> Thanks,
> Janusz
> 

Best regards,
Baolu