[Deepin-Kernel-SIG] [linux 6.6.y] [Upstream] cxl/core: Fix caching dport GPF DVSEC issue

[opsiff]

mainline inclusion
from mainline-v6.15-rc4
category: bugfix

Per Table 8-2 in CXL r3.2 section 8.1.1 and CXL r3.2 section 8.1.6, only CXL Downstream switch ports and CXL root ports have GPF DVSEC for CXL Port(DVSEC ID 04h).

CXL subsystem has a gpf_dvsec in struct cxl_port which is used to cache the offset of a GPF DVSEC in PCIe configuration space. It will be updated during the first EP attaching to the cxl_port, so the gpf_dvsec can only cache the GPF DVSEC offset of the dport which the first EP is under. Will not have chance to update it during other EPs attaching. That means CXL subsystem will use the same GPF DVSEC offset for all dports under the port, it will be a problem if the GPF DVSEC offset cached in cxl_port is not the right offset for a dport.

Moving gpf_dvsec from struct cxl_port to struct cxl_dport, make every cxl dport has their own GPF DVSEC offset caching, and each cxl dport uses its own GPF DVSEC offset for GPF DVSEC accessing.

Fixes: a52b6a2 ("cxl/pci: Support Global Persistent Flush (GPF)")

Reviewed-by: Davidlohr Bueso dave@stgolabs.net
Reviewed-by: Jonathan Cameron Jonathan.Cameron@huawei.com
Reviewed-by: Dan Williams dan.j.williams@intel.com
Tested-by: Davidlohr Bueso dave@stgolabs.net
Link: https://patch.msgid.link/20250323093110.233040-2-ming.li@zohomail.com

(cherry picked from commit 87d2de0)

Summary by Sourcery

Move CXL Global Persistent Flush (GPF) DVSEC caching from the shared port structure to individual downstream port structures so each dport maintains its own GPF DVSEC offset.

Bug Fixes:

• Ensure each CXL downstream port caches and uses its own GPF DVSEC offset instead of sharing a single offset at the port level, preventing incorrect DVSEC access across dports.

Enhancements:

• Simplify GPF setup by updating the cxl_gpf_port_setup API to operate directly on cxl_dport objects and adjust callers accordingly.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Moves cached GPF DVSEC tracking from the shared cxl_port to individual cxl_dport instances so each downstream port maintains its own DVSEC offset, updating the GPF setup helper API and its callers accordingly.

File-Level Changes

Change	Details	Files
Track GPF DVSEC offset per downstream port instead of per port and update GPF setup API usage	Change cxl_gpf_port_setup() to take a struct cxl_dport, use dport->dport_dev, and store/read the cached GPF DVSEC offset in dport->gpf_dvsec Move the gpf_dvsec field from struct cxl_port to struct cxl_dport, updating the structure definitions in the CXL headers Adjust the cxl_gpf_port_setup() prototype in the core header to match the new dport-based signature Update devm_cxl_enumerate_ports() to call cxl_gpf_port_setup() with the cxl_dport instead of the raw device and port pair	drivers/cxl/core/pci.c drivers/cxl/cxl.h drivers/cxl/core/core.h drivers/cxl/core/port.c

---

Tips and commands

Interacting with Sourcery

• Trigger a new review: Comment @sourcery-ai review on the pull request.
• Continue discussions: Reply directly to Sourcery's review comments.
• Generate a GitHub issue from a review comment: Ask Sourcery to create an
  issue from a review comment by replying to it. You can also reply to a
  review comment with @sourcery-ai issue to create an issue from it.
• Generate a pull request title: Write @sourcery-ai anywhere in the pull
  request title to generate a title at any time. You can also comment
  @sourcery-ai title on the pull request to (re-)generate the title at any time.
• Generate a pull request summary: Write @sourcery-ai summary anywhere in
  the pull request body to generate a PR summary at any time exactly where you
  want it. You can also comment @sourcery-ai summary on the pull request to
  (re-)generate the summary at any time.
• Generate reviewer's guide: Comment @sourcery-ai guide on the pull
  request to (re-)generate the reviewer's guide at any time.
• Resolve all Sourcery comments: Comment @sourcery-ai resolve on the
  pull request to resolve all Sourcery comments. Useful if you've already
  addressed all the comments and don't want to see them anymore.
• Dismiss all Sourcery reviews: Comment @sourcery-ai dismiss on the pull
  request to dismiss all existing Sourcery reviews. Especially useful if you
  want to start fresh with a new review - don't forget to comment
  @sourcery-ai review to trigger a new review!

Customizing Your Experience

Access your dashboard to:

• Enable or disable review features such as the Sourcery-generated pull request
  summary, the reviewer's guide, and others.
• Change the review language.
• Add, remove or edit custom review instructions.
• Adjust other review settings.

Getting Help

• Contact our support team for questions or feedback.
• Visit our documentation for detailed guides and information.
• Keep in touch with the Sourcery team by following us on X/Twitter, LinkedIn or GitHub.

[Avenger-285714]

/approve

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Avenger-285714

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• deepin/OWNERS [Avenger-285714]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[sourcery-ai]

Hey - I've reviewed your changes and they look great!

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[Copilot]

Pull request overview

Fixes incorrect Global Persistent Flush (GPF) DVSEC offset caching in the CXL core by moving the cache from the shared cxl_port object to per-downstream-port (cxl_dport) storage, ensuring DVSEC accesses use the correct offset for each dport.

Changes:

• Move gpf_dvsec caching from struct cxl_port to struct cxl_dport.
• Update cxl_gpf_port_setup() to operate on a struct cxl_dport * and adjust its caller accordingly.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
drivers/cxl/cxl.h	Relocates the cached gpf_dvsec field from cxl_port to cxl_dport and updates kerneldoc accordingly.
drivers/cxl/core/port.c	Updates the enumeration path to call cxl_gpf_port_setup() with the relevant cxl_dport.
drivers/cxl/core/pci.c	Changes cxl_gpf_port_setup() to cache/read the DVSEC per-dport and use dport->dport_dev for config access.
drivers/cxl/core/core.h	Updates the cxl_gpf_port_setup() prototype to accept struct cxl_dport *.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.