Re: Doubt on KVM-88 vulnerabilities

[Michael Tokarev <mjt@tls.msk.ru>]

Asdo wrote:
> Thanks for your reply,
> sorry to get you angry, but there are still things which are not clear 
> to me.

Well, today wasn't my best day.
You're right the documentation on the matter is nearly non-existing.

[]
> 3) Everyone here mentions to upgrade the userspace part only. That 
> sounds strange to me because in all kernelmode+usermode applications I 
> have seen up to now, the usermode part was just there to drive the 
> kernelmode part (basically parse commandline parameters and communicate 
> them to the kernel) Ok I understand that in KVM also the emulated 

In kvm it's the opposite.  Kernel part is very small and the interface
does not change as frequently.  It's basically just a wrapper around
the CPU VT extensions.

[]
> But what about stable kernel modules?
> 
> Are these the kvm-kmod's?

Yes.

> And besides, the versioning of kvm-kmod's are not obvious to me: I see 
> these ones at sourceforge:
> 
> 2.6.31.5
> 2.6.30
> 2.6.30.1
> 2.6.30-rc8
> 2.6.30-rc6
> 
> I don't undestand why they are numbered like the kernel, that's 
> strange... More specifically, this is the question: If I have a kernel 
> version N, what kvm-kmod can I compile in it? If I can just compile 
> version N, then it's useless because that's identical to the kvm.ko I 
> already had. Or can I compile kvm-kmod 2.6.31.5 in my kernel 2.6.24? 
> That's a strange version numbering... why haven't you used the same 
> numbering as for qemu-kvm?

Because such numbering proved to be confusing, and you are confused by
it too.  The above numbers means just like, kvm-kmod from kernel 2.6.30.1
(say), but "ported" to a wider range of kernels.  kvm-kmod is being
developed as part of kernel.


Btw, 2.6.24 and in fact anything before ~2.6.28 might be problematic for
real kvm usage, due to other parts of the kernel.  Applies to both
host and guest kernels.

/mjt