RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 1083537 - When running a KVM Windows guest, need to turn on all the "hv_*" flags
Summary: When running a KVM Windows guest, need to turn on all the "hv_*" flags
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: virt-manager
Version: 7.1
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Pavel Hrdina
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks: 1092813
TreeView+ depends on / blocked
 
Reported: 2014-04-02 12:16 UTC by Ronen Hod
Modified: 2019-01-03 16:00 UTC (History)
10 users (show)

Fixed In Version: virt-manager-1.2.1-3.el7
Doc Type: Bug Fix
Doc Text:
Clone Of: 1083525
: 1092813 1168881 (view as bug list)
Environment:
Last Closed: 2015-11-19 05:22:30 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2015:2206 0 normal SHIPPED_LIVE virt-manager bug fix and enhancement update 2015-11-19 08:17:29 UTC

Description Ronen Hod 2014-04-02 12:16:30 UTC 
+++ This bug was initially created as a clone of Bug #1083525 +++

Description of problem:
As of RHEL7.0 QEMU and Libvirt support several Hyper-V Enlightenment features, that need to be explicitly turned on for Windows guests. It is forbidden to turn them on for RHEL5 guests.
The QEMU flags are: "hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time"

Additional info:
hv_relaxed turns off an internal Windows watchdog, and by doing so avoids some high load BSODs
hv_relaxed is also supported in RHEL6 as of RHEL6.4
All the other flags are performance optimization flags, that can improve the performance by 10% to much more (in extreme cases of resources overcommit).

Libvirt related bugs:
RHEL7
 Bug 1056205 - new cpu's flags, to control hyper-v related features - hv-time
 Bug 784836 - new cpu's flags, to control hyper-v related features
RHEL6
 Bug 864606 - [RFE] Enable Hyper-V Enlightenment for Windows guests

Note: You might want to duplicate this BZ to other RHEL7 based versions of RHOS.
Comment 1 Giuseppe Scrivano 2014-11-28 10:04:12 UTC 
I think that this OS information should go into libosinfo first, and virt-manager just uses it.  Probably this requires a new API for libosinfo. 

Cloning there...
Comment 5 Pavel Hrdina 2015-07-07 13:19:47 UTC 
Upstream commit:

commit 8ea634f9e437153a30f06b7267db2bd685af0561
Author: Cole Robinson <crobinso>
Date:   Sun Jul 6 18:46:16 2014 -0400

    guest: Enable Hyper-v Enlightenments for Windows VMs
    
    These are the recommended defaults for all windows VMs, when using
    a new enough libvirt + kvm. Some more details in this boxes bug report:
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732811
Comment 14 Xiaodai Wang 2015-07-29 06:09:50 UTC 
I verified this bug in latest virt-manager.
virt-manager-1.2.1-4.el7.noarch

Steps:
1. Install a windows guest, run "ps aux | grep $winguest" to check the hv flags.
# ps aux | grep win7 | grep hv

Actual Result:
All the hv flags are turned on.
# ps aux | grep win7 | grep hv
-cpu SandyBridge,hv_time,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff

I think this bug only about windows guest, so from above result, it's fixed.
But i have a question for RHEL guest. In additional info, it says "hv_relaxed is also supported in RHEL6 as of RHEL6.4". I installed a rhel6.7 guest, but can't see hv flags explicitly. Does that mean it's supported implicitly?
Comment 15 Pavel Hrdina 2015-07-29 14:45:05 UTC 
It means that RHEL6.4 supports setting 'hv_relaxed' for windows guests, not that rhel6 guest will use this feature.
Comment 16 Xiaodai Wang 2015-07-30 01:58:41 UTC 
(In reply to Pavel Hrdina from comment #15)
> It means that RHEL6.4 supports setting 'hv_relaxed' for windows guests, not
> that rhel6 guest will use this feature.

oh, i see, thanks! 
Move the bug to VERIFIED.
Comment 18 errata-xmlrpc 2015-11-19 05:22:30 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2206.html
Note You need to log in before you can comment on or make changes to this bug.