Re: Setting nx bit in virtual CPU

[Richard Simpson <rs1002@huskydog.org.uk>]

Nope, both Kernels are 64 bit.

uname -a Host: Linux gordon 2.6.27-gentoo-r8 #5 Sat Mar 14 18:01:59 GMT
2009 x86_64 AMD Athlon(tm) 64 Processor 3200+ AuthenticAMD GNU/Linux

uname -a Guest: Linux andrew 2.6.28-hardened-r9 #4 Mon Jan 18 22:39:31
GMT 2010 x86_64 AMD Athlon(tm) 64 Processor 3200+ AuthenticAMD GNU/Linux

As you can see, both kernels are a little old, and I have been wondering
if that might be part of the problem.  The Guest one is old because that
is the latest stable hardened version in Gentoo.  The host one is old
because of:

(gordon:~) rs10% uptime
 22:01:37 up 374 days, 23:29,  1 user,  load average: 1.09, 0.42, 0.18

Now that I have managed to smash the psychologically important 1 year
uptime for the first time ever (Woo!) I shall probably upgrade the host
kernel in the near future.  Of course, it is important to remember that
with the --no-kvm switch it works just fine (only slowly) with exactly
the same two kernels.

Thanks

On 01/04/10 09:43, Avi Kivity wrote:
> On 03/30/2010 01:16 AM, Richard Simpson wrote:
>> Hello,
>>
>> Summary: How can I have a virtual CPU with the nx bit set whilst
>> enjoying KVM acceleration?
>>
>> My Host - AMD Athlon(tm) 64 Processor 3200+ running Gentoo
>> My VM - KVM running hardened Gentoo
>> My KVM version - 0.12.3
>> My Task - Implement restricted secure VM to handle services exposed to
>> internet.
>> My Command - kvm -hda /dev/mapper/vols-andrew -kernel ./bzImage -append
>> root=/dev/hda2 -cpu host -runas xxx -net nic -net user -m 256 -k en-gb
>> -vnc :1 -monitor stdio
>>
>>    
> 
> 
> Are you running a 32-bit non-pae host kernel?  In that case, nx is
> disabled both for the guest and host.  Switch to a pae (or 64-bit)
> kernel and all should be well.
>