Re: [PATCH v13 09/19] x86: Secure Launch kernel early boot stub

[ross . philipson]

On 4/15/25 3:15 PM, Sean Christopherson wrote:
> On Tue, Apr 15, 2025, Andrew Cooper wrote:
> > On 11/04/2025 10:40 pm, Sean Christopherson wrote:
> > > On Thu, Apr 10, 2025, Ross Philipson wrote:
> > > > +	 * instruction can return for a number of reasons. Test to see if it returned
> > > > +	 * because the monitor was written to.
> > > > +	 */
> > > > +	monitor
> > > > +
> > > > +1:
> > > > +	mfence
> > > > +	mwait
> > > > +	movl	(%eax), %edx
> > > Why load the value into EDX?  At a glance, the value is never consumed.
> > >
> > > > +	testl	%edx, %edx
> > > > +	jz	1b
> > > This usage of MONITOR/MWAIT is flawed.  The monitor needs to be re-armed in each
> > > loop, otherwise mwait will be a glorified nop.
> > >
> > > More importantly, the exit condition needs to be checked before monitor,
> >
> > after monitor and before mwait.
>
> Gah, yeah, I mean to say "before mwait".

Thanks Sean and Andy, I will fix this.

Ross