Re: Centos 7 newer kernel needed

Laurentiu Soica <laurentiu@xxxxxxxx> · Thu, 04 Aug 2016 12:30:12 +0000

Hi Xlord, 
Yes,  the CPU has support for EPT. 

I wrongly thought that the nested EPT was first introduced in 3.12. Following your instructions I see that I have it enabled on my system as well. 

However,  checking the kernel commits from 3.12 on search string 'nested ept'  I found about 10 code changes/fixes for nested EPT. 

https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/log/?id=refs%2Ftags%2Fv3.12.62&qt=grep&q=Nested+ept

What options do I have to get this commits on a Centos 7 kernel? 

Thank you, 
Laurentii

On Thu, Aug 4, 2016, 12:14 -=X.L.O.R.D=- <xlord.sl@xxxxxxxxx> wrote:
Dear Laurentiu,
Could you please check if your CPU supported from /proc/cpuinfo and lscpu ?

EPT supported
Xlord

From: -=X.L.O.R.D=- [mailto:xlord.sl@xxxxxxxxx] 
Sent: Thursday, August 4, 2016 5:12 PM
To: 'Laurentiu Soica' <laurentiu@xxxxxxxx>; 'Discussion about the virtualization on CentOS' <centos-virt@xxxxxxxxxx>
Subject: RE: [CentOS-virt] Centos 7 newer kernel needed

Dear Laurentiu,
Assume your hardware does support Intel VT-x with EPT supported, I have also look into the kernel part for fun!
Just quick look at CentOS 7 and installed a CentOS_7x_x64_build1511 @installation at minimum, below is my sharing and hope to help!
1)      CentOS Linux Kernel version: 3.10.0-327.e17.x86_64 SMP
2)      Kernel parameters which should be your requirement;
a.     Default “kvm-intel.ept=1” (refer to Kernel Archive “https://www.kernel.org/”)
b.     
Xlord

From: Laurentiu Soica [mailto:laurentiu@xxxxxxxx] 
Sent: Thursday, August 4, 2016 2:41 PM
To: -=X.L.O.R.D=- <xlord.sl@xxxxxxxxx>; Discussion about the virtualization on CentOS <centos-virt@xxxxxxxxxx>
Subject: Re:  Centos 7 newer kernel needed

Hello Xlord, 

The CPU does have VT support and I already have the nested KVM enabled. 

Checking the Linux Kernel release notes I saw that the nested kvm feature was implemented in 3.10 but he EPT support is in 3.12.

So Centos 7's kernel which is 3.10 does have the EPT support? Is there a way to check that the EPT support is available in the kernel? 

Thank you, 
Laurentiu
On Thu, Aug 4, 2016, 06:04 -=X.L.O.R.D=- <xlord.sl@xxxxxxxxx> wrote:
Dear Laurentiu,
Please check below info since assume your CentOS7 box CPU processor already VT supported in advance.
1)     Checkpoint #1: Hardware and Kernel modules
a.     cat /proc/cpuinfo | grep vmx
b.     cat /sys/module/kvm_intel/parameters/nested (if “N” then go to checkpoint #2)
2)     Checkpoint #2: Assume your CentOS box support
a.     echo 'options kvm-intel nested=y' >> /etc/modprobe.d/dist.conf
b.     modprobe kvm-intel
3)      Checkpoint #3: Verification
a.       Reboot yout CentOS box
b.     cat /sys/module/kvm_intel/parameters/nested (if “Y” then you can carry one process the KVM installation.

PS: Source: https://lalatendu.org/2015/11/01/kvm-nested-virtualization-in-fedora-23/ which should be very similar with CentOS and CentOS 7 already capable with on with KVM Nested EPT with CPU pass-through options supported. Hope that helps & cheers!!
Xlord

From: centos-virt-bounces@xxxxxxxxxx [mailto:centos-virt-bounces@xxxxxxxxxx] On Behalf Of Laurentiu Soica
Sent: Thursday, August 4, 2016 3:07 AM
To: centos-virt@xxxxxxxxxx
Subject:  Centos 7 newer kernel needed

Hello, 

I am looking for a Linux kernel for Centos 7 that implements a feature introduced in kernel version 3.12:

"nested EPT support to KVM's nested VMX."

If anyone has used this feature with Centos 7, please let me know. 

Laurentiu 
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