qemu 1:2.11+dfsg-1ubuntu7.4 hangs when -cpu POWER9 is specified
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
qemu (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Bionic |
Fix Released
|
Undecided
|
Unassigned | ||
Cosmic |
Fix Released
|
Undecided
|
Unassigned |
Bug Description
[Impact]
* The qemu code prior to qemu 3.0 has an issue where the power9 machine
spec makes the guest issue unsupported instructions. Qemu has to be
adapted to be able to understand that and not break.
* backport of upstream fix https:/
[Test Case]
* Run a guest in P9 mode, on guest init it will hang - with the fix it
will reach a login prompt.
Feel free to use the provided initrd to boot from.
Any host Bionic+ kernel seems to do, so we are just reusing the hosts
vmlinuz.
$ wget https:/
$ qemu-system-ppc64 -nographic -vga none -M pseries,cap-htm=off -cpu POWER9 -m 1G -kernel /boot/vmlinux-
[Regression Potential]
* The change is very limited to just the PPC eieio instruction, so if any
it can only affect that. Also the new type is only part of the P9 spec,
so any guest running in older modes won't be affected either.
Those guests that would be affected by a potentially bad emulation
error in the new code are those that didn't work at all so far -
therefore it might contain a but but should not regress something
working today.
Only if there would be "another" eieio instruction source out there
with bit 6 set (I know of none) that code would be able to regress
those cases.
[Other Info]
* n/a
----
== Comment: #0 - Murilo Opsfelder Araujo <email address hidden> - 2018-08-15 15:08:52 ==
---Problem Description---
qemu 1:2.11+
Bisecting qemu, I found this patch:
https:/
With a small tweak, it applies on qemu 2.11.1 from bionic and fixes the hang.
This was originally reported as a kernel bug at https:/
Contact Information = Murilo Opsfelder Araujo <email address hidden>
---uname output---
Linux jaspion1 4.15.0-30-generic #32-Ubuntu SMP Thu Jul 26 17:43:11 UTC 2018 ppc64le ppc64le ppc64le GNU/Linux
Machine Type = na
---Debugger---
A debugger is not configured
---Steps to Reproduce---
wget https:/
qemu-system-ppc64 -nographic -vga none -M pseries,cap-htm=off -cpu POWER9 -m 1G -kernel /boot/vmlinux-
Userspace tool common name: qemu
The userspace tool has the following bit modes: 64-bit
Userspace rpm: qemu
Userspace tool obtained from project website: na
*Additional Instructions for Murilo Opsfelder Araujo <email address hidden>:
-Attach ltrace and strace of userspace application.
== Comment: #1 - Murilo Opsfelder Araujo <email address hidden> - 2018-08-15 15:26:53 ==
I'll provide a debdiff.
tags: | added: architecture-ppc64le bugnameltc-170602 severity-medium targetmilestone-inin--- |
affects: | ubuntu → qemu (Ubuntu) |
description: | updated |
tags: |
added: targetmilestone-inin1804 removed: targetmilestone-inin--- |
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