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

[ross.philipson at oracle.com]

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