Bug 592114

Summary:	vmx and other CPU flags not shown in Xen kernel
Product:	Red Hat Enterprise Linux 5	Reporter:	Gary Case <gcase>
Component:	kernel-xen	Assignee:	Xen Maintainance List <xen-maint>
Status:	CLOSED DUPLICATE	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	high	Docs Contact:
Priority:	high
Version:	5.5	CC:	drjones, xen-maint
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2010-05-14 01:28:05 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Gary Case 2010-05-13 22:17:24 UTC

Description of problem:
The xen kernel only shows a limited number of CPU flags.

Version-Release number of selected component (if applicable):
RHEL5.5 (-194 kernel)

How reproducible:
Every time

Steps to Reproduce:
1. Install RHEL5.5 and look at /proc/cpuinfo in bare metal and xen kernels
2. Notice important CPU flags like 'vmx' are missing in xen kernel
3.
  
Actual results:
Missing CPU flags in Xen kernel

Expected results:
All CPU flags present in Xen kernel

Additional info:
This will halt system certification on any model experiencing this issue. The impact on the certification program is being discussed in Bug 576497

Comment 1 Gary Case 2010-05-13 22:18:14 UTC

Here's an example:

Core i5 650 on 5.5 Xen kernel (-194)
flags        : fpu tsc msr pae cx8 apic mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc ida arat pni est ssse3 cx16 sse4_1 sse4_2 popcnt lahf_lm

Core i5 650 on 5.5 bare metal kernel (-194)
flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx rdtscp lm constant_tsc ida nonstop_tsc arat pni monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr sse4_1 sse4_2 popcnt lahf_lm

Comment 2 Andrew Jones 2010-05-14 01:28:05 UTC

I've thought about this issue before (see the bug I'm dupping this to). The thing is that dom0 is just a guest, so really the only way to see all the flags from it is to query the HV using some path where the HV doesn't "lie". cpuid will return whatever the HV wants to.

*** This bug has been marked as a duplicate of bug 570091 ***