linux-kernel - Re: [PATCH RFC v2 0/4] Disable ATS via iommu during PCI resets

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Message-ID: <20250727162041.GC7551@nvidia.com>
Date: Sun, 27 Jul 2025 13:20:41 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Ethan Zhao <etzhao1900@...il.com>
Cc: Nicolin Chen <nicolinc@...dia.com>, joro@...tes.org, will@...nel.org,
	robin.murphy@....com, rafael@...nel.org, lenb@...nel.org,
	bhelgaas@...gle.com, iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-pci@...r.kernel.org, patches@...ts.linux.dev,
	pjaroszynski@...dia.com, vsethi@...dia.com, helgaas@...nel.org,
	baolu.lu@...ux.intel.com
Subject: Re: [PATCH RFC v2 0/4] Disable ATS via iommu during PCI resets

On Sun, Jul 27, 2025 at 08:48:26PM +0800, Ethan Zhao wrote:

> At least, we can do some attempt in DPC and Hot-plug driver, and then
> push the hardware specification update to provide pre-reset notification for
> DPC & hotplug. does it make sense ?

I think DPC is a different case..

If we get a DPC we should also push the iommu into blocking, disable
ATS and abandon any outstanding ATC invalidations as part of
recovering from the DPC. Once everythings is cleaned up we can set the
iommu back up again and allow the driver to recover the device.

I think the current series is a good step along that path, but we'd
also need to improve the drivers to handle abandonding/aborting the
ATC invalidations.

IMHO DPC and SW initiated reset are separate projects.

Jason