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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:
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.
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 ***