Re: [PATCH v1 3/4] ACPI: OSL: Allow Notify () handlers to run on all CPUs

Andy Shevchenko
2023-11-29T14:09:11Z

On Wed, Nov 29, 2023 at 02:50:54PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Notify () handlers, like GPE handlers, are only allowed to run on CPU0
> now out of the concern that they might trigger an SMM trap and that (in
> some cases) the SMM code running as a result of that might corrupt
> memory if not run on CPU0.

Pardon my French, but I'm a bit lost in the semantics of all those "that".
Maybe the above can be simplified?

> However, Notify () handlers are registered by kernel code and they
> are not likely to evaluate AML that would trigger an SMM trap. In
> fact, many of them don't even evaluate any AML at all and even if
> they do, that AML may as well be evaluated in other code paths. In
> other words, they are not special from the AML evaluation perspective,
> so there is no real reason to treat them in any special way.
>
> Accordingly, allow Notify () handlers, unlike GPE handlers, to be
> executed by all CPUs in the system.
>
> Also adjust the allocation of the "notify" workqueue to allow multiple
> handlers to be executed at the same time, because they need not be
> serialized.

Code wise LGTM,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

--
With Best Regards,
Andy Shevchenko