Bug 813132

Summary: "sep" flag is defined in dump but can not find it in host, should have warning message when booting guest
Product: Red Hat Enterprise Linux 6 Reporter: FuXiangChun <xfu>
Component: qemu-kvmAssignee: Eduardo Habkost <ehabkost>
Status: CLOSED DUPLICATE QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.3CC: acathrow, areis, bsarathy, chayang, dyasny, flang, juzhang, michen, mkenneth, qzhang, shu, sluo, virt-maint
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 814426 (view as bug list) Environment:
Last Closed: 2012-04-20 20:46:49 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:

Description FuXiangChun 2012-04-17 03:02:09 UTC 
Description of problem:
can find "sep" flag in /usr/libexec/qemu-kvm -cpu ?dump and cann't find it /proc/cpuinof on host. but haven't any warning message when booting guest.
BTW, "sep" isn't exposted to guest.

"rdtscp" flag is defined in dump and /proc/cpuinfo on host but it isn't exposted to guest. 

Version-Release number of selected component (if applicable):
# uname -r
2.6.32-259.el6.x86_64
#rpm -qa|grep qemu
qemu-kvm-0.12.1.2-2.270.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1./usr/libexec/qemu-kvm -M rhel6.3.0 -cpu SandyBridge --enable-kvm -m 4G -smp
40,sockets=2,cores=10,threads=2,maxcpus=41 -name rhel6.3 -uuid
ddcbfb49-3411-1701-3c36-6bdbc00bedbb -rtc base=utc,clock=host,driftfix=slew
-boot c  -drive
file=/mnt/rhel6.3.raw,format=raw,if=none,id=disk0,cache=none,werror=stop,rerror=stop
-device virtio-scsi-pci,id=disk0 -device
scsi-hd,drive=disk0,scsi-id=0,lun=0,bootindex=1 -netdev tap,id=hostnet1 -device
virtio-net-pci,netdev=hostnet1,id=net1,mac=86:12:50:a4:32:72 -spice
port=5911,disable-ticketing -vga qxl -device sga -chardev
socket,id=serial0,path=/var/test1,server,nowait -device
isa-serial,chardev=serial0 -balloon virtio -monitor
unix:/tmp/monitor1,server,nowait -monitor stdio

2. find "sep" flag from dump 
   
3. find "rdtscp" flag from dump and cpuinfo on host

4. check above two flags in guest
  
Actual results:
1. can find "sep" from dump, no any warning message when booting guest.
2. can find "rdtscp" from dump and cpuinfo on host,but cann't find it from guest

Expected results:
qemu should have warning message because "sep" flag isn't defined in host.
rdtscp should expose to guest.

Additional info:
Comment 2 Eduardo Habkost 2012-04-19 20:37:41 UTC 
I have opened Bug 814426 for the "sep" flag (proposed for 6.4).

The "sep" flag is supposed to be supported by the kernel, though. I will investigate why it is not being visible to the guest.
Comment 3 Eduardo Habkost 2012-04-20 20:46:49 UTC 
After investigating a bit, I found out that the "sep" flag is actually being disabled by the kernel (it is not listed at /proc/cpuinfo and not returned by kvm_arch_get_supported_cpuid()). I don't know exactly why, but once the kernel disables the flag, Qemu is doing the right thing by disabling it too.

What's not corect is to not warn when using "enforce" or "check". But that's already being tracked on bug 692374.

*** This bug has been marked as a duplicate of bug 692374 ***