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From: Robin Murphy <robin.murphy@arm.com>
To: Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Hanjun Guo <guohanjun@huawei.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Len Brown <lenb@kernel.org>, Russell King <linux@armlinux.org.uk>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Danilo Krummrich <dakr@kernel.org>,
	Stuart Yoder <stuyoder@gmail.com>,
	Laurentiu Tudor <laurentiu.tudor@nxp.com>,
	Nipun Gupta <nipun.gupta@amd.com>,
	Nikhil Agarwal <nikhil.agarwal@amd.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Rob Herring <robh@kernel.org>,
	Saravana Kannan <saravanak@google.com>,
	Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
	devicetree@vger.kernel.org, linux-pci@vger.kernel.org,
	Charan Teja Kalla <quic_charante@quicinc.com>
Subject: [PATCH 0/2] iommu: Fix the longstanding probe issues
Date: Thu, 13 Feb 2025 23:48:58 +0000	[thread overview]
Message-ID: <cover.1739486121.git.robin.murphy@arm.com> (raw)

Hi all,

Finally, it's that thing I've been mentioning on and off for the last 5
years or so! After far too much thinking about "clean" ways to refactor
everything towards an eventual goal of working properly, I finally gave
up and decided to see how bad it would be to just get it working, then
worry about cleaning up afterwards. Frankly I still can't quiet believe
how small the patch turned out to be...

Patch #1 is a fix for what I think is the only "expected" race in the
core API design - we knew we had that window where a default domain is
NULL, but the potential consequences weren't clear until Charan figured
it out the hard way. That should be good to go already, and it's not
strictly a dependency for patch #2, but it seemed worth posting them
together on the common theme.

Patch #2 is then the first big bite out of the problem I feel compelled
to fix because it's my name on d7b0558230e4 ("iommu/of: Prepare for
deferred IOMMU configuration") which, in hindsight, started it. I hope
this will be the only patch which has to touch absolutely everything all
at once. I've not got very far with the follow-up patches yet, but I do
foresee being able to tackle the driver core, firmware subsystems and
bus drivers more independently. I don't expect anyone to love it, but I
hope you can at least see where I'm going and give a bit of leeway for
now :)

I also do rather expect that WARN_ON to be hit, but the intent is that
I'd like to get the attention of any of_dma_configure() abusers so they
can help me figure out what the heck their code *should* be doing...

Thanks,
Robin.


Robin Murphy (2):
  iommu: Handle race with default domain setup
  iommu: Get DT/ACPI parsing into the proper probe path

 drivers/acpi/arm64/dma.c        |  5 ++++
 drivers/acpi/scan.c             | 10 +++----
 drivers/amba/bus.c              |  2 +-
 drivers/base/platform.c         |  2 +-
 drivers/bus/fsl-mc/fsl-mc-bus.c |  2 +-
 drivers/cdx/cdx.c               |  2 +-
 drivers/iommu/iommu.c           | 48 +++++++++++++++++++++++++--------
 drivers/iommu/of_iommu.c        | 10 ++++++-
 drivers/of/device.c             |  7 ++++-
 drivers/pci/pci-driver.c        |  2 +-
 10 files changed, 65 insertions(+), 25 deletions(-)

-- 
2.39.2.101.g768bb238c484.dirty


             reply	other threads:[~2025-02-13 23:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-13 23:48 Robin Murphy [this message]
2025-02-13 23:48 ` [PATCH 1/2] iommu: Handle race with default domain setup Robin Murphy
2025-02-14 12:57   ` Charan Teja Kalla
2025-02-17 16:29     ` Robin Murphy
2025-02-14 19:43   ` Jason Gunthorpe
2025-02-13 23:49 ` [PATCH 2/2] iommu: Get DT/ACPI parsing into the proper probe path Robin Murphy
2025-02-14 17:29   ` Bjorn Helgaas
2025-02-14 20:14   ` Jason Gunthorpe
2025-02-17 15:00     ` Robin Murphy
2025-02-19 18:29       ` Jason Gunthorpe
2025-02-19 22:43   ` Rob Herring

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