linux-kernel - RE: [PATCH v3 02/11] iommu/vt-d: Remove clearing translation data in disable_dmar

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Date:   Fri, 1 Jul 2022 07:58:03 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>
CC:     "Raj, Ashok" <ashok.raj@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 02/11] iommu/vt-d: Remove clearing translation data in
 disable_dmar_iommu()

> From: Lu Baolu <baolu.lu@...ux.intel.com>
> Sent: Wednesday, June 29, 2022 3:47 PM
> 
> The disable_dmar_iommu() is called when IOMMU initialization fails or
> the IOMMU is hot-removed from the system. In both cases, there is no
> need to clear the IOMMU translation data structures for devices.
> 
> On the initialization path, the device probing only happens after the
> IOMMU is initialized successfully, hence there're no translation data
> structures.
> 
> On the hot-remove path, there is no real use case where the IOMMU is
> hot-removed, but the devices that it manages are still alive in the
> system. The translation data structures were torn down during device
> release, hence there's no need to repeat it in IOMMU hot-remove path
> either. This removes the unnecessary code and only leaves a check.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>

You probably overlooked my last comment on kexec:

https://lore.kernel.org/lkml/BL1PR11MB52711A71AD9F11B7AE42694C8CAC9@BL1PR11MB5271.namprd11.prod.outlook.com/

I think my question is still not answered.