Bug 1229432 - Backport {Haswell,Broadwell}-noTSX cpu models
Summary: Backport {Haswell,Broadwell}-noTSX cpu models
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Red Hat Enterprise Virtualization Manager
Classification: Red Hat
Component: vdsm
Version: 3.5.0
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
: 3.5.5
Assignee: Nobody
QA Contact: Aharon Canan
URL:
Whiteboard: virt
Depends On: 1213053
Blocks: 1218673
TreeView+ depends on / blocked
 
Reported: 2015-06-08 17:50 UTC by Dan Kenigsberg
Modified: 2019-11-14 06:49 UTC (History)
29 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of: 1213053
Environment:
Last Closed: 2015-08-04 08:53:40 UTC
oVirt Team: Infra
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)

Description Dan Kenigsberg 2015-06-08 17:50:09 UTC
+++ This bug was initially created as a clone of Bug #1213053 +++

Description of problem:

As bug 1182650 says, Haswell and Broadwell processors are patched to disable TSX instructions according to erratum released by Intel. This introduces VM incompatibility between Haswell processors with TSX and without TSX when explicitly specified as cpumodel='Haswell'. The upstream qemu introduced new cpu models, Haswell-noTSX and Broadwell-noTSX namely to address this issue.
Bug 1182650 fixes the problem in the libvirt part. This bug intends to address qemu.

Here's a link to the upstream commit:
http://git.qemu.org/?p=qemu.git;a=commitdiff;h=a356850b80b3d13b2ef737dad2acb05e6da03753

I believe that the same issue affects RHEL6, which would need to keep running on TSX-less hosts for years to come.

Comment 1 Ademar Reis 2015-06-10 14:00:41 UTC
Closing as duplicate of 1186405, which is CLOSED/WONTFIX. You can find a workaround in https://bugzilla.redhat.com/show_bug.cgi?id=1186405#c5

You requested the z-stream flag for this BZ... So if you don't agree with the WONTFIX, please ellaborate on the reasons for that.

*** This bug has been marked as a duplicate of bug 1186405 ***

Comment 2 Dan Kenigsberg 2015-06-22 08:24:25 UTC
Vdsm can report model_Haswell-noTSX and model_Broadwell-noTSX flags on el6 if it finds "SandyBridge + extra features" on the host, so that Engine can make use of these CPUs. The logic can sit also in Engine, too.

Comment 3 Michal Skrivanek 2015-06-24 09:52:37 UTC
(In reply to Dan Kenigsberg from comment #2)
> Vdsm can report model_Haswell-noTSX and model_Broadwell-noTSX flags on el6
> if it finds "SandyBridge + extra features" on the host, so that Engine can
> make use of these CPUs. The logic can sit also in Engine, too.

if you're willing to take in this hack then it's possible, however doing this in libvirt makes much more sense to me. There they map flags to models. Would that be feasible?

Comment 7 Michal Skrivanek 2015-08-04 08:53:40 UTC
considering we're getting closer to 3.6 and there are no customer reports (surprisingly, though) I'm closing the request


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