Re: Linux with kvm-intel locks up VMplayer guest is started

[Anthony Liguori]

Avi Kivity wrote:
> Anthony Liguori wrote:
> > We know exactly what the problem is.  KVM activates VT 
> > unconditionally.  There's no hardware mechanism to arbitrate access 
> > to VT.  KVM is the only thing in the Linux kernel that uses VT so we 
> > don't have a software mechanism to arbitrate access to VT.
> >
> > If the VMware code was upstream, then we could work together to make 
> > a software arbitration mechanism.  It's not, and worse yet, it's 
> > closed source so there's no chance it will be.  Even if someone wrote 
> > an arbitration mechanism and got VMware to use it, it still shouldn't 
> > be merged because KVM would be the only thing using that mechanism 
> > upstream.  I'm not interested in adding kernel infrastructure to 
> > support external binary kernel modules.
>
> Well a recent patch from Eli Collins mentioned VMware are 
> standardizing CR4.VMXE as an indicator of whether someone is using the 
> VT hardware or not, and now kvm clears that bit when unloading.  We 
> could check the bit and fail if is set, thus have working mutual 
> exclusion.  Of course, it will only work with newer versions of kvm 
> and vmware.

Yup, but the original bug reporter would not be helped by this.

> I don't see any reason to poke sticks into the wheels here.

An occasional poke at binary kernel modules is always a good thing IMHO :-)

Regards,

Anthony Liguori

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/