[UBUNTU] QEMU toleration patch to ensure cpu detection in a nested KVM
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| Ubuntu on IBM z Systems |
Fix Released
|
High
|
Canonical Server | ||
| qemu (Ubuntu) |
Fix Released
|
Undecided
|
Skipper Bug Screeners | ||
| Bionic |
Fix Released
|
Undecided
|
Unassigned | ||
| Cosmic |
Fix Released
|
Undecided
|
Unassigned | ||
| Disco |
Fix Released
|
Undecided
|
Unassigned | ||
| Eoan |
Fix Released
|
Undecided
|
Skipper Bug Screeners | ||
Bug Description
[Impact]
* The kernel detects CPU types and enables/disables some features based
on that. With future HW this detection is broken as the csske facility
is no more available.
* This is fixed upstream and here backported, the csske is ignored when
expanding the cpu model for the guest and thereby the issue avoided.
[Test Case]
* Start a kvm guest on s390x
* While doing so qemu/kvm will try to detect the host model
* Check what CPU it detects the model
* Note: this will work (regression check) on all s390x HW, but to prove
the fix and trigger the issue one would need experimental (not GA yet)
HW or a similator. Hence we are relying on the bug reporter for
verification.
* For the functionality of this check the initial commit adding the
core feature [1] which shows how the filtering works.
[1]: https:/
[Regression Potential]
* If there would be a detection that depends on csske being available or
not that would be affected. But there is none that this is important
for. All existing machines still have csske, for those the issue never
existed and nothing should change. The behavior on new machines will
"change", but not regress. And in addition those new HW was never sold
yet, so even if that would be considered a regression it wouldn't
happen in the field.
[Other Info]
* n/a
---
A nested KVM hypervisor has problems to detect the cpu type as z10..z14 with no csske facility available. Instead it will fall back to z9.
We need a backport of
commit eaf6f642abf1d4d
Author: Christian Borntraeger <email address hidden>
AuthorDate: Mon Apr 29 05:02:43 2019 -0400
Commit: Cornelia Huck <email address hidden>
CommitDate: Tue May 21 16:59:16 2019 +0200
s390x/cpumodel: ignore csske for expansion
...
Signed-off-by: Christian Borntraeger <email address hidden>
Cc: <email address hidden>
Reviewed-by: David Hildenbrand <email address hidden>
Message-Id: <email address hidden>
Signed-off-by: Cornelia Huck <email address hidden>
diff --git a/target/
index e5afa15512.
--- a/target/
+++ b/target/
@@ -1322,6 +1322,8 @@ static void init_ignored_
+ /* CSSKE is deprecated on newer generations */
+ S390_FEAT_
};
int i;
This patch is also needed for Ubuntu 18.04 and 19.04.
18.10 will be out of service in July.....
| tags: | added: architecture-s39064 bugnameltc-177881 severity-high targetmilestone-inin1910 |
| Changed in ubuntu: | |
| assignee: | nobody → Skipper Bug Screeners (skipper-screen-team) |
| affects: | ubuntu → qemu (Ubuntu) |
| summary: |
- QEMU toleration patch to ensure cpu detection in a nested KVM + [UBUNTU] QEMU toleration patch to ensure cpu detection in a nested KVM |
| Changed in qemu (Ubuntu Bionic): | |
| status: | New → Triaged |
| Changed in qemu (Ubuntu Cosmic): | |
| status: | New → Triaged |
| Changed in qemu (Ubuntu Disco): | |
| status: | New → Triaged |
| Changed in qemu (Ubuntu Eoan): | |
| status: | New → Triaged |
| Changed in ubuntu-z-systems: | |
| status: | New → Triaged |
| importance: | Undecided → High |
| assignee: | nobody → Canonical Server Team (canonical-server) |
| Christian Ehrhardt (paelzer) wrote | #1 |
| Christian Ehrhardt (paelzer) wrote | #2 |
| Launchpad Janitor (janitor) wrote | #3 |
| Changed in qemu (Ubuntu Eoan): | |
| status: | Triaged → Fix Released |
| Changed in ubuntu-z-systems: | |
| status: | Triaged → In Progress |
| Łukasz Zemczak (sil2100) wrote | #4 |
| Timo Aaltonen (tjaalton) wrote Please test proposed package | #6 |
| Changed in qemu (Ubuntu Disco): | |
| status: | Triaged → Fix Committed |
| tags: | added: verification-needed verification-needed-disco |
| Changed in qemu (Ubuntu Cosmic): | |
| status: | Triaged → Fix Committed |
| tags: | added: verification-needed-cosmic |
| Timo Aaltonen (tjaalton) wrote | #7 |
| Changed in qemu (Ubuntu Bionic): | |
| status: | Triaged → Fix Committed |
| tags: | added: verification-needed-bionic |
| Timo Aaltonen (tjaalton) wrote | #8 |
| Changed in ubuntu-z-systems: | |
| status: | In Progress → Fix Committed |
| Frank Heimes (fheimes) wrote | #9 |
| Christian Ehrhardt (paelzer) wrote | #10 |
| bugproxy (bugproxy) wrote Comment bridged from LTC Bugzilla | #11 |
| tags: |
added: verification-done verification-done-bionic verification-done-cosmic verification-done-disco removed: verification-needed verification-needed-bionic verification-needed-cosmic verification-needed-disco |
| Launchpad Janitor (janitor) wrote | #12 |
| Changed in qemu (Ubuntu Bionic): | |
| status: | Fix Committed → Fix Released |
| Steve Langasek (vorlon) wrote Update Released | #13 |
| Launchpad Janitor (janitor) wrote | #14 |
| Changed in qemu (Ubuntu Cosmic): | |
| status: | Fix Committed → Fix Released |
| Launchpad Janitor (janitor) wrote | #15 |
| Changed in qemu (Ubuntu Disco): | |
| status: | Fix Committed → Fix Released |
| Changed in ubuntu-z-systems: | |
| status: | Fix Committed → Fix Released |
| bugproxy (bugproxy) wrote Comment bridged from LTC Bugzilla | #16 |
| bugproxy (bugproxy) wrote | #17 |
Tested the PPA for general regressions which seems ok. The actual change needs special HW which for now we can only ask IBM to test or ack.