[24.04_linux-nvidia-6.17]: Backport PCI/MSI: Enable memory decoding before restoring MSI-X messages#472
Closed
nvmochs wants to merge 1 commit into
Conversation
… messages The current MSI-X restoration path assumes the Command register Memory bit is enabled when writing MSI-X messages. But its possible the last saved and restored state of device may not have the Memory bit enabled, even if a device driver later enables Memory bit and MSI-X. Attempting to access Memory space without Memory bit enabled can lead to Unsupported Request (UR) from the device. Fix this by enabling Memory bit and restore it afterwards. Signed-off-by: Farhan Ali <alifm@linux.ibm.com> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@kernel.org> (cherry picked from https://lore.kernel.org/all/20260622171840.1618-5-alifm@linux.ibm.com/) Signed-off-by: Matthew R. Ochs <mochs@nvidia.com>
Collaborator
BaseOS Kernel ReviewSummaryNo significant issues found; the only finding is minor grammatical errors in the commit message body of d3b5b98, which have no functional impact. Findings: Critical: 0, High: 0, Medium: 0, Low: 1 Latest watcher review: open review Kernel deb build: failed (failure log, build artifacts) Head: This comment is maintained by nv-pr-bot. It is updated when the GitHub watcher publishes a newer review. |
Contributor
PR Validation ReportPatchscan ✅ No Missing FixesAll cherry-picked commits checked — no missing upstream fixes found. PR Lint ✅ All checks passedDetailsChecking 1 commits... Cherry-pick digest: ┌──────────────┬──────────────────────────────────────────────────────────────────┬────────────┬─────────┬───────────────────────────┐ │ Local │ Referenced upstream / Patch subject │ Patch-ID │ Subject │ SoB chain │ ├──────────────┼──────────────────────────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤ │ d3b5b98154e2 │ [SAUCE] pci/msi: enable memory decoding before restoring msi-x m │ N/A │ N/A │ alifm, mochs │ └──────────────┴──────────────────────────────────────────────────────────────────┴────────────┴─────────┴───────────────────────────┘ Lint: all checks passed. |
clsotog
approved these changes
Jun 25, 2026
clsotog
left a comment
clsotog
left a comment
Collaborator
There was a problem hiding this comment.
Acked-by: Carol L Soto <csoto@nvidia.com>
sforshee
approved these changes
Jun 25, 2026
sforshee
left a comment
sforshee
left a comment
Collaborator
There was a problem hiding this comment.
Acked-by: Seth Forshee <sforshee@nvidia.com>
nirmoy
added
has_2_acks
and removed
help wanted
Collaborator
Author
|
Merged, closing PR. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
During VFIO/FLR recovery, the saved PCI Command register state may have Memory Space disabled. Restoring MSI-X messages in that state can issue MMIO writes to the MSI-X table while memory decoding is off, causing Unsupported Request completions and DPC containment on the root port.
The patch enables
PCI_COMMAND_MEMORYbefore MSI-X restore and restores the original Command register value afterward.The patch is currently under review on LKML and is therefore taking as SAUCE: https://lore.kernel.org/all/c8abc1c8-71e0-443f-820f-182c0ff931e9@linux.ibm.com/
Note that the patch applied cleanly.
As of now, this issue only impacts VR systems as GB is currently configured to treat UR as ANF.
Validation
scripts/checkpatch.pl --strict --git HEADgit diff --check HEAD~1 HEADNvbug: 6375598
LP: https://bugs.launchpad.net/ubuntu/+source/linux-nvidia-bos/+bug/2158328