From: Jason Gunthorpe <jgg@nvidia.com>
To: dan.j.williams@intel.com
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
Nicolin Chen <nicolinc@nvidia.com>,
"will@kernel.org" <will@kernel.org>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"praan@google.com" <praan@google.com>,
"baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
"miko.lenczewski@arm.com" <miko.lenczewski@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>
Subject: Re: [PATCH RFCv1 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices
Date: Wed, 28 Jan 2026 09:05:20 -0400 [thread overview]
Message-ID: <20260128130520.GV1134360@nvidia.com> (raw)
In-Reply-To: <69795d0366a9_1d33100d3@dwillia2-mobl4.notmuch>
On Tue, Jan 27, 2026 at 04:49:07PM -0800, dan.j.williams@intel.com wrote:
> > Yes, ARM took the position that ATS should be left disabled for
> > IDENTITY both because of SMMU constraints and also because it made
> > some sense that you wouldn't want ATS overhead just to get a 1:1
> > translation.
>
> Does this mean that ARM already today does not enable ATS until driver
> attach, or is incremental work needed for that capability?
All of the iommu drivers setup an iommu translation and enable ATS
before any driver is bound.
We would need to do more work in the core to leave the translation
blocked when there is no driver. I don't think it is that difficult
> > Drivers need to ensure that ATS is disabled at PCI and Translated
> > requestes blocked in IOMMU HW while a BLOCKED domain is attached.
>
> "Drivers" here meaning IOMMU drivers, right?
Yes
Jason
next prev parent reply other threads:[~2026-01-28 13:05 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-17 4:56 [PATCH RFCv1 0/3] Allow ATS to be always on for certain ATS-capable devices Nicolin Chen
2026-01-17 4:56 ` [PATCH RFCv1 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices Nicolin Chen
2026-01-19 17:58 ` Jason Gunthorpe
2026-01-21 8:01 ` Tian, Kevin
2026-01-21 10:03 ` Jonathan Cameron
2026-01-21 13:03 ` Jason Gunthorpe
2026-01-22 1:17 ` Baolu Lu
2026-01-22 13:15 ` Jason Gunthorpe
2026-01-22 5:44 ` dan.j.williams
2026-01-22 13:14 ` Jason Gunthorpe
2026-01-22 16:29 ` Nicolin Chen
2026-01-22 16:58 ` Jason Gunthorpe
2026-01-22 19:46 ` dan.j.williams
2026-01-27 8:10 ` Tian, Kevin
2026-01-27 15:04 ` Jason Gunthorpe
2026-01-28 0:49 ` dan.j.williams
2026-01-28 13:05 ` Jason Gunthorpe [this message]
2026-02-03 5:13 ` Nicolin Chen
2026-02-03 14:33 ` Jason Gunthorpe
2026-02-03 17:45 ` Nicolin Chen
2026-02-03 17:55 ` Jason Gunthorpe
2026-02-03 18:50 ` Nicolin Chen
2026-02-04 13:21 ` Jason Gunthorpe
2026-02-03 18:59 ` Robin Murphy
2026-02-03 19:24 ` Nicolin Chen
2026-02-03 23:16 ` Jason Gunthorpe
2026-02-04 12:18 ` Robin Murphy
2026-02-04 13:20 ` Jason Gunthorpe
2026-02-18 22:56 ` Nicolin Chen
2026-02-19 14:37 ` Jason Gunthorpe
2026-02-19 16:53 ` Nicolin Chen
2026-02-19 17:41 ` Jason Gunthorpe
2026-02-20 4:52 ` Nicolin Chen
2026-02-20 12:50 ` Jason Gunthorpe
2026-02-20 13:22 ` Robin Murphy
2026-02-20 13:51 ` Jason Gunthorpe
2026-02-20 14:45 ` Robin Murphy
2026-02-26 15:10 ` Jason Gunthorpe
2026-02-20 18:49 ` Nicolin Chen
2026-02-24 14:38 ` Jason Gunthorpe
2026-01-28 0:57 ` Tian, Kevin
2026-01-28 13:11 ` Jason Gunthorpe
2026-01-29 3:28 ` Tian, Kevin
2026-01-22 10:24 ` Alejandro Lucero Palau
2026-01-17 4:56 ` [PATCH RFCv1 2/3] PCI: Allow ATS to be always on for non-CXL NVIDIA GPUs Nicolin Chen
2026-01-19 18:00 ` Jason Gunthorpe
2026-01-19 18:09 ` Nicolin Chen
2026-01-17 4:56 ` [PATCH RFCv1 3/3] iommu/arm-smmu-v3: Allow ATS to be always on Nicolin Chen
2026-01-19 20:06 ` Jason Gunthorpe
2026-01-26 12:39 ` Will Deacon
2026-01-26 17:20 ` Jason Gunthorpe
2026-01-26 18:40 ` Nicolin Chen
2026-01-26 19:16 ` Jason Gunthorpe
2026-01-26 18:49 ` Robin Murphy
2026-01-26 19:09 ` Jason Gunthorpe
2026-01-27 13:10 ` Will Deacon
2026-01-27 13:26 ` Robin Murphy
2026-01-27 13:50 ` Will Deacon
2026-01-27 14:49 ` Jason Gunthorpe
2026-01-26 18:21 ` Nicolin Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260128130520.GV1134360@nvidia.com \
--to=jgg@nvidia.com \
--cc=baolu.lu@linux.intel.com \
--cc=bhelgaas@google.com \
--cc=dan.j.williams@intel.com \
--cc=iommu@lists.linux.dev \
--cc=jonathan.cameron@huawei.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-cxl@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=miko.lenczewski@arm.com \
--cc=nicolinc@nvidia.com \
--cc=praan@google.com \
--cc=robin.murphy@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox