powerpc/powernv/pci: Work around races in PCI bridge enabling
| Affects | Status | Importance | Assigned to | Milestone | ||
|---|---|---|---|---|---|---|
| | The Ubuntu-power-systems project |
Critical
|
Canonical Kernel Team | |||
| linux (Ubuntu) | Status tracked in Cosmic | |||||
| | Xenial |
Critical
|
Joseph Salisbury | |||
| | Bionic |
Critical
|
Joseph Salisbury | |||
| | Cosmic |
Critical
|
Joseph Salisbury | |||
Bug Description
== Comment: #0 - Michael Ranweiler <email address hidden> - 2018-08-21 13:52:03 ==
+++ This bug was initially created as a clone of Bug #170766 +++
Please apply the following kernel patch:
powerpc/
The generic code is racy when multiple children of a PCI bridge try to
enable it simultaneously.
This leads to drivers trying to access a device through a
not-yet-enabled bridge, and this EEH errors under various
circumstances when using parallel driver probing.
There is work going on to fix that properly in the PCI core but it
will take some time.
x86 gets away with it because (outside of hotplug), the BIOS enables
all the bridges at boot time.
This patch does the same thing on powernv by enabling all bridges that
have child devices at boot time, thus avoiding subsequent races. It's
suitable for backporting to stable and distros, while the proper PCI
fix will probably be significantly more invasive.
Signed-off-by: Benjamin Herrenschmidt <email address hidden>
Cc: <email address hidden>
Signed-off-by: Michael Ellerman <email address hidden>
== Comment: #2 - Michael Ranweiler <email address hidden> - 2018-08-21 18:23:35 ==
This has some fuzz and also move it back from the pci macro to dev_err so we'll attach the backported patch.
| tags: | added: architecture-ppc64le bugnameltc-170793 severity-critical targetmilestone-inin--- |
| Changed in ubuntu: | |
| assignee: | nobody → Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage) |
| affects: | ubuntu → kernel-package (Ubuntu) |
| Changed in ubuntu-power-systems: | |
| assignee: | nobody → Canonical Kernel Team (canonical-kernel-team) |
| importance: | Undecided → Critical |
| tags: | added: triage-g |
| affects: | kernel-package (Ubuntu) → linux (Ubuntu) |
| Changed in linux (Ubuntu Bionic): | |
| status: | New → In Progress |
| Changed in linux (Ubuntu Cosmic): | |
| status: | New → In Progress |
| Changed in linux (Ubuntu Bionic): | |
| importance: | Undecided → Critical |
| Changed in linux (Ubuntu Cosmic): | |
| importance: | Undecided → Critical |
| Changed in linux (Ubuntu Bionic): | |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Changed in linux (Ubuntu Cosmic): | |
| assignee: | Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage) → Joseph Salisbury (jsalisbury) |
| Joseph Salisbury (jsalisbury) wrote : | #1 |
| Changed in ubuntu-power-systems: | |
| status: | New → In Progress |
| Changed in linux (Ubuntu Xenial): | |
| status: | New → In Progress |
| importance: | Undecided → Critical |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Joseph Salisbury (jsalisbury) wrote : | #2 |
I also built a Xenial test kernel with commit db2173198b9513f
The Xenial test kernel is available from:
http://
| Manoj Iyer (manjo) wrote : | #3 |
IBM, could you please verify the PPA test kernels provided by the kernel team, and report back here.
| Changed in ubuntu-power-systems: | |
| status: | In Progress → Incomplete |
I built a test kernel with commit db2173198b95. The test kernel can be downloaded from:
http://
Can you test this kernel and see if it resolves this bug?
Note about installing test kernels:
• If the test kernel is prior to 4.15(Bionic) you need to install the linux-image and linux-image-extra .deb packages.
• If the test kernel is 4.15(Bionic) or newer, you need to install the linux-modules, linux-modules-extra and linux-image-
Thanks in advance!