Re: [PATCH 1/2] vmx,svm: Add module parameter to ignore the 'in use' check

[Avi Kivity <avi@redhat.com>]

On 07/05/2011 12:56 PM, Sasha Levin wrote:
> Please note that I don't have access to the hardware in question, this
> was done over IRC.
>

I understand that.  Can you get in contact with the reporter again?

> Here are the steps taken in debugging this issue:
>
> 1. Looking at the dmesg ( http://pastebin.com/eM7bDY8r ) we saw that
> when trying to load the kvm module, the following error shows up: 'kvm:
> enabling virtualization on CPU0 failed'.
>
> 2. We went through the lsmod output (unfortunately I don't have the link
> as it's gone from my IRC buffer) and didn't see any modules belonging to
> other hypervisors.
>
> 3. At that point, looking at the code - we figured that a set SVM flag
> is the possible culprit since it's the only code path which fails
> loading the module with that error message without printing anything
> else.
>
> 4. Installed msr-tools and injected the msr module so that we could read
> msr values from userspace.
>
> 5. Ran 'rdmsr 0xc0000080' to read the extended feature register. The
> output had bit 12 set - which means that SVM bit was enabled.
>
> 6. Ran 'wrmsr 0xc0000080 0xd01' which disabled the SVM bit.
>
> 7. kvm module loaded ok.

My questions are:

- was a BIOS update attempted?  at least VMware uses the same check as 
kvm, and probably virtualbox as well, so this problem should have been 
seen before.
- was the vendor contacted?  Not that I think we'll see a lot of good 
from that.
- was this after a reset or cold boot?
- maybe a stealth rootkit is involved?

-- 
error compiling committee.c: too many arguments to function