Re: [PATCH 2/2] KVM: VMX: Initialize vm86 TSS only once.

[Avi Kivity <avi@redhat.com>]

On 02/27/2011 06:27 PM, Gleb Natapov wrote:
> >
> >  Or we can keep the old behaviour.  If KVM_SET_TSS_ADDR hasn't been
> >  called by the time of the first entry into real mode (the first
> >  KVM_CREATE_VCPU?), use the top of the first slot.
> >
> Do we require that KVM_SET_TSS_ADDR is called before first KVM_CREATE_VCPU?
> We may still break some theoretical userspaces this way.

The documentation doesn't say, but I think it's unlikely that userspace 
will start a guest and then configure it.

>
> >  We can avoid the SMP problem by initializing the memory in a single
> >  pass, writing each byte exactly once with its final value.  This way
> >  concurrent initialization doesn't corrupt an in-use TSS.
> >
> Sounds hackish, but may work. Doing so will make entering pmode much
> more slow.

Why?  do it at most once per vcpu.

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