Re: [PATCH v3 3/3] x86/acpi, x86/boot: Add multiprocessor wake-up support

From: Andi Kleen
Date: Mon May 10 2021 - 13:22:49 EST

On Mon, May 10, 2021 at 10:10:24AM -0700, Kuppuswamy, Sathyanarayanan wrote:
> On 5/10/21 9:55 AM, Rafael J. Wysocki wrote:
> > I'm not sure how my comment regarding the fact that for a given CPU
> > this function is only usable once has been addressed.
> >
> > While it may not be a practical concern in the use case that you are
> > after (TDX), this is a generic mechanism and it needs to cover other
> > possible usage scenarios.
> For the same CPU, if we try to use mailbox again, firmware will not
> respond to it. So the command will timeout and return error.

Right because the firmware code doesn't run anymore.

The only possibility would be for Linux to put back some code that spins
and waits again, but that would be quite pointless and wasteful.