Bug 1039745

Summary:	qemu vcpu hotplug support for q35 machine type
Product:	Red Hat Enterprise Linux 7	Reporter:	Igor Mammedov <imammedo>
Component:	qemu-kvm-rhev	Assignee:	Igor Mammedov <imammedo>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.0	CC:	hhuang, imammedo, juzhang, michen, rbalakri, virt-maint, xfu
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	QEMU 2.0	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-03-05 09:43:15 UTC	Type:	Bug
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:	726328

Description Igor Mammedov 2013-12-09 21:50:21 UTC

CPU hot-add was implemented for piix based machines and Q35 based machines still miss it. It's needed to factor out common ACPI bits of CPU hot-plug code and reuse it for Q35 as well.

Patch to factor out need generic ACPI bits was posted as part of memory hotplug series http://lists.gnu.org/archive/html/qemu-devel/2013-11/msg02526.html
Once it is committed, I can post CPU specific patch to add feature to Q35.

Comment 3 Igor Mammedov 2014-02-05 13:26:16 UTC

QE,
Please retest when RHEL7.1 is ready.

Comment 4 Igor Mammedov 2014-02-05 13:29:55 UTC

upstream fix:
http://lists.gnu.org/archive/html/qemu-devel/2014-01/msg00997.html

Comment 5 juzhang 2014-07-31 05:58:20 UTC

Update the component to qemu-kvm-rhev since this bz is fixed in qemu2.0, fix me if there is wrong.

Best Regards,
Junyi

Comment 6 FuXiangChun 2014-08-05 06:23:10 UTC

Verify this bug with qemu-kvm-1.5.3-53.el7.x86_64 and qemu-kvm-1.5.3-66.el7.x86_64 and qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64

For RHEL7.0 guest with qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64 & qemu-kvm-1.5.3-66.el7.x86_64 & qemu-kvm-1.5.3-53.el7.x86_64 on Intel host.

1./usr/libexec/qemu-kvm -M q35 -smp 8,cores=2,threads=2,sockets=2,maxcpus=160...

2.{ "execute": "cpu-add", "arguments": { "id": 9 }} 

3.check vcpu number from qemu-kvm HMP
(qemu) info cpus
* CPU #0: pc=0xfffff8037f21f1ff (halted) thread_id=13221
  CPU #1: pc=0xfffff8037f21f1ff (halted) thread_id=13222
  CPU #2: pc=0xfffff8037f21f1ff (halted) thread_id=13223
  CPU #3: pc=0xfffff8037f21f1ff (halted) thread_id=13224
  CPU #4: pc=0xfffff8000039f37e thread_id=13225
  CPU #5: pc=0xfffff8037f21f1ff (halted) thread_id=13226
  CPU #6: pc=0xfffff8037f21f1ff (halted) thread_id=13227
  CPU #7: pc=0xfffff8037f21f1ff (halted) thread_id=13228
  CPU #8: pc=0xfffff8037f21f1ff (halted) thread_id=13232

4. check vcpu number inside guest
 
can find 9 vcpu inside guest from /proc/cpuinfo


For win2012r2 guest with qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64 on AMD host 

Got the same result with RHEL7.0 guest.

Test summary.
1. qemu-kvm-1.5.3-53.el7.x86_64 & qemu-kvm-1.5.3-66.el7.x86_64 & qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64 support vcpu hotplug

2. For linux and windows guest, both support vcpu hotplug on AMD & Intel host.

Igor,

1.According to this test result above.
Is this bug fixed?  

2.qemu-kvm-1.5.3-53.el7.x86_64 and qemu-kvm-1.5.3-66.el7.x86_64 support vcpu hotplug as well.  Is it expect?

Comment 7 Igor Mammedov 2014-09-01 08:40:24 UTC

(In reply to FuXiangChun from comment #6)
> Verify this bug with qemu-kvm-1.5.3-53.el7.x86_64 and
> qemu-kvm-1.5.3-66.el7.x86_64 and qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64
> 
> For RHEL7.0 guest with qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64 &
> qemu-kvm-1.5.3-66.el7.x86_64 & qemu-kvm-1.5.3-53.el7.x86_64 on Intel host.
> 
> 1./usr/libexec/qemu-kvm -M q35 -smp
> 8,cores=2,threads=2,sockets=2,maxcpus=160...
> 
> 2.{ "execute": "cpu-add", "arguments": { "id": 9 }} 
> 
> 3.check vcpu number from qemu-kvm HMP
> (qemu) info cpus
> * CPU #0: pc=0xfffff8037f21f1ff (halted) thread_id=13221
>   CPU #1: pc=0xfffff8037f21f1ff (halted) thread_id=13222
>   CPU #2: pc=0xfffff8037f21f1ff (halted) thread_id=13223
>   CPU #3: pc=0xfffff8037f21f1ff (halted) thread_id=13224
>   CPU #4: pc=0xfffff8000039f37e thread_id=13225
>   CPU #5: pc=0xfffff8037f21f1ff (halted) thread_id=13226
>   CPU #6: pc=0xfffff8037f21f1ff (halted) thread_id=13227
>   CPU #7: pc=0xfffff8037f21f1ff (halted) thread_id=13228
>   CPU #8: pc=0xfffff8037f21f1ff (halted) thread_id=13232
> 
> 4. check vcpu number inside guest
>  
> can find 9 vcpu inside guest from /proc/cpuinfo
> 
> 
> For win2012r2 guest with qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64 on AMD
> host 
> 
> Got the same result with RHEL7.0 guest.
> 
> Test summary.
> 1. qemu-kvm-1.5.3-53.el7.x86_64 & qemu-kvm-1.5.3-66.el7.x86_64 &
> qemu-kvm-rhev-2.1.0-3.el7ev.preview.x86_64 support vcpu hotplug
> 
> 2. For linux and windows guest, both support vcpu hotplug on AMD & Intel
> host.
> 
> Igor,
> 
> 1.According to this test result above.
> Is this bug fixed?  
looks like it is.

> 
> 2.qemu-kvm-1.5.3-53.el7.x86_64 and qemu-kvm-1.5.3-66.el7.x86_64 support vcpu
> hotplug as well.  Is it expect?
1.5.3 supports CPU hotadd only for piix4 machine, if one tries to use it for q35 machine, CPU will be added (info cpus) but guest won't see it until reboot, since q35 ACPI parts are missing.

Comment 10 errata-xmlrpc 2015-03-05 09:43:15 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/RHSA-2015-0624.html