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 1254124 - -cpu $cpu-model,+invtsc doesn't support migration
Summary: -cpu $cpu-model,+invtsc doesn't support migration
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm-rhev
Version: 7.2
Hardware: x86_64
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Marcelo Tosatti
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2015-08-17 08:37 UTC by Pei Zhang
Modified: 2016-03-28 09:18 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2015-08-17 16:43:34 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Pei Zhang 2015-08-17 08:37:44 UTC 
Description of problem:
'-cpu $cpu-model,+invtsc' doesn't support migration. 

Version-Release number of selected component (if applicable):
Host:
Kernel:3.10.0-304.el7.x86_64
qemu-kvm-rhev:qemu-kvm-rhev-2.3.0-18.el7.x86_64
/proc/cpuinfo:
processor	: 31
vendor_id	: AuthenticAMD
cpu family	: 21
model		: 2
model name	: AMD Opteron(tm) Processor 6376                 
stepping	: 0
microcode	: 0x6000832
cpu MHz		: 2300.000
cache size	: 2048 KB
physical id	: 1
siblings	: 16
core id		: 7
cpu cores	: 8
apicid		: 79
initial apicid	: 47
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid amd_dcm aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 popcnt aes xsave avx f16c lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm topoext perfctr_core perfctr_nb arat cpb hw_pstate npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold bmi1
bogomips	: 4587.94
TLB size	: 1536 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 48 bits physical, 48 bits virtual
power management: ts ttp tm 100mhzsteps hwpstate cpb eff_freq_ro


How reproducible:
100%

Steps to Reproduce:
1.
# /usr/libexec/qemu-kvm -cpu Opteron_G5,+invtsc -monitor stdio

2.
# /usr/libexec/qemu-kvm -cpu Opteron_G5,+invtsc -monitor stdio -incoming tcp:0:6666 

3.
(qemu) migrate -d tcp:10.66.9.120:6666
migrate: State blocked by non-migratable device 'cpu'


Actual results:
migrate: State blocked by non-migratable device 'cpu'

Expected results:
Should migrate successfully.

Additional info:
When using '-cpu host,+invtsc', migration works well. And Using '-cpu Opteron_G5,fpu' also works well.
Comment 1 FuXiangChun 2015-08-17 08:56:04 UTC 
Eduardo,

Is it a valid problem?
Comment 3 Karen Noel 2015-08-17 14:44:55 UTC 
> When using '-cpu host,+invtsc', migration works well.

I thought any use of invtsc should disallow live migration. Marcelo?
Comment 4 Eduardo Habkost 2015-08-17 16:43:34 UTC 
This is expected. We must block migration if invtsc is enabled, and it would be a bug if we didn't block it.
Comment 5 Pei Zhang 2015-08-18 00:24:20 UTC 
(In reply to Eduardo Habkost from comment #4)
> This is expected. We must block migration if invtsc is enabled, and it would
> be a bug if we didn't block it.

According to Comment 4, using '-cpu host,+invtsc' should also disallow live migration, but it it allowed. Only using'-cpu $cpu-model,+invtsc' can not migrate.
Comment 6 Eduardo Habkost 2015-08-19 16:10:47 UTC 
(In reply to zhangpei from comment #5)
> (In reply to Eduardo Habkost from comment #4)
> > This is expected. We must block migration if invtsc is enabled, and it would
> > be a bug if we didn't block it.
> 
> According to Comment 4, using '-cpu host,+invtsc' should also disallow live
> migration, but it it allowed. Only using'-cpu $cpu-model,+invtsc' can not
> migrate.

You should always test using either "enforce" or "check" flags ("enforce" is preferred). invtsc is being silently disabled because "-cpu host" runs with migratable=on by default, and it prevents unmigratable features from being enabled. With -cpu host, you need "-cpu host,migratable=off,+invtsc,enforce". I know it is confusing, but we had to do it to make sure "-cpu host" is a migratable CPU model by default (as long as host CPU, host QEMU version and host kernel stay the same).
Comment 7 Pei Zhang 2015-08-20 11:13:43 UTC 
(In reply to Eduardo Habkost from comment #6)
> (In reply to zhangpei from comment #5)
> > (In reply to Eduardo Habkost from comment #4)
> > > This is expected. We must block migration if invtsc is enabled, and it would
> > > be a bug if we didn't block it.
> > 
> > According to Comment 4, using '-cpu host,+invtsc' should also disallow live
> > migration, but it it allowed. Only using'-cpu $cpu-model,+invtsc' can not
> > migrate.
> 
> You should always test using either "enforce" or "check" flags ("enforce" is
> preferred). invtsc is being silently disabled because "-cpu host" runs with
> migratable=on by default, and it prevents unmigratable features from being
> enabled. With -cpu host, you need "-cpu
> host,migratable=off,+invtsc,enforce". I know it is confusing, but we had to
> do it to make sure "-cpu host" is a migratable CPU model by default (as long
> as host CPU, host QEMU version and host kernel stay the same).

Hi Eduardo,
Thanks for your explain. I tried according to Comments 6 and now understand this cpu flag well.

# /usr/libexec/qemu-kvm -cpu host,+invtsc,enforce -monitor stdio
QEMU 2.3.0 monitor - type 'help' for more information
(qemu) warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 0]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 1]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 2]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 3]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 4]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 5]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 6]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 7]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 8]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 9]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 12]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 13]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 14]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 15]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 16]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 17]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 23]
warning: host doesn't support requested feature: CPUID.80000001H:EDX [bit 24]
warning: host doesn't support requested feature: CPUID.80000007H:EDX.invtsc [bit 8]
qemu-kvm: Host doesn't support requested features


# /usr/libexec/qemu-kvm -cpu host,migratable=off,+invtsc,enforce -monitor stdio
QEMU 2.3.0 monitor - type 'help' for more information
(qemu) VNC server running on `::1:5900'
(qemu) migrate -d tcp:10.66.12.153:6666
migrate: State blocked by non-migratable device 'cpu'
Note You need to log in before you can comment on or make changes to this bug.