Re: [PATCH v12 07/22] x86/virt/tdx: Add skeleton to enable TDX on demand

[Huang, Kai]

On Wed, 2023-06-28 at 15:35 +0200, Peter Zijlstra wrote:
> On Wed, Jun 28, 2023 at 12:28:12AM +0000, Huang, Kai wrote:
> > On Tue, 2023-06-27 at 22:37 +0000, Huang, Kai wrote:
> > > > > 
> > > > > +/*
> > > > > + * Do the module global initialization if not done yet.
> > > > > + * It's always called with interrupts and preemption disabled.
> > > > > + */
> > > > 
> > > > If interrupts are always disabled why do you need _irqsave()?
> > > > 
> > > 
> > > I'll remove the _irqsave().
> > > 
> > > AFAICT Isaku preferred this for additional security, but this is not
> > > necessary.
> > > 
> > > 
> > 
> > Damn.  I think we can change the comment to say this function is called with
> > preemption being disabled, but _can_ be called with interrupt disabled.  And we
> > keep using the _irqsave() version.
> > 
> > 	/*
> > 	 * Do the module global initialization if not done yet.  It's always
> > 	 * called with preemption disabled and can be called with interrupts
> > 	 * disabled.
> > 	 */
> 
> That's still not explaining *why*, what you want to say is:
> 
> 	Can be called locally or through an IPI function call.
> 

Thanks.  As in another reply, if using spinlock is OK, then I think we can say
it will be called either locally or through an IPI function call.  Otherwise, we
do via a new separate function tdx_global_init() and no lock is needed in that
function.  The caller should call it properly.