Re: [RFC PATCH] iommu/vt-d: Fix IOMMU field not populated on device hot re-plug

From: Lu Baolu
Date: Mon Sep 02 2019 - 21:31:08 EST

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.


Best regards,