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

[Sean Christopherson]

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".