Bug 2294180
| Summary: | KOP L2 guest fails to boot with 1 core - SMT8 topology | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | IBM Bug Proxy <bugproxy> |
| Component: | kernel | Assignee: | Kernel Maintainer List <kernel-maint> |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | high | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | rawhide | CC: | acaringi, adscvr, airlied, alciregi, bskeggs, bugproxy, dan, hdegoede, hpa, josef, kernel-maint, linville, masami256, mchehab, ptalbert, steved, suraj.ghimire7 |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | ppc64 | ||
| OS: | All | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2024-10-07 08:04:44 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 1071880 | ||
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Description
IBM Bug Proxy
2024-06-25 06:21:07 UTC
== Comment: #0 - Gautam G Menghani <Gautam.Menghani> - 2024-02-19 08:00:04 ==
KOP L2 guest fails to boot when we set the CPU topology as 1 core - SMT 8
command line used to verify the issue:
#!/bin/sh
QEMU="/home/mgautam/qemu"
qemu-system-ppc64 -s \
-drive file=/root/debian-12-nocloud-ppc64el.qcow2,format=qcow2 \
-m 20G \
-smp 8,cores=1,sockets=1,threads=8 \
-cpu host \
-nographic \
-machine pseries,ic-mode=xics -accel kvm \
-net nic,model=virtio \
-net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10022-:22
NOTE: L2 boots fine when doorbells are turned off in L1 kernel
== Comment: #1 - Gautam G Menghani <Gautam.Menghani> - 2024-04-03 05:57:24 ==
With the latest PPC linux as L1 and default distro qcow2 on L2, this problem replicates when emulated XICS IC mode is used ('-machine pseries, ic-mode=xics') . When we use the default emulated xive, this problem is not observed.
Having the latest ppc linux tree in L2 does not solve the problem, but after disabling doorbells in L2, the problem is not observed
== Comment: #2 - Gautam G Menghani <Gautam.Menghani> - 2024-05-21 02:54:06 ==
As per the investigation so far, the doorbell exception is not getting fired inside L2 guest. At L1 level, if we set DPDES=1 in the GSB for L2, the guest never receives the doorbell and also it is never cleared from the GSB. We are discussing this behaviour with phyp team.
== Comment: #3 - Gautam G Menghani <Gautam.Menghani> - 2024-05-22 06:43:17 ==
The root cause of this issue is lack of DPDES support at L1. I've posted the fix upstream - https://lore.kernel.org/linuxppc-dev/20240522084949.123148-1-gautam@linux.ibm.com/T/#u
== Comment: #4 - Gautam G Menghani <Gautam.Menghani> - 2024-06-10 00:25:39 ==
The fix has been accepted upstream and will be backported for kernels >= 6.7
https://lore.kernel.org/linuxppc-dev/20240605113913.83715-1-gautam@linux.ibm.com/
------- Comment From Gautam.Menghani 2024-10-07 03:44 EDT------- I tested this case with latest fedora 40 and 41 kernels, and the issue does not reproduce. I am able to boot the guests with XICS and SMT8 just fine. Thanks for rechecking. F-40 is on 6.10 and F-41 on 6.11 and the fixes went to those releases, closing. |