Subject: Re: [RFC PATCH 00/20] mshv: enable kexec with Hyper-V donated pages and partitions

From: Jork Loeser <[email-masked]>
Date: Mon, 1 Jun 2026 13:09:41 -0700 (PDT)

On Sun, 31 May 2026, Mike Rapoport wrote:

> Hi Jork,

>>  - A freeze mechanism to lock the tree before serializing for kexec
>>    (patch 13).
>
> There were a lot of effort to make KHO stateless and drop the requirement
> for finalization/freeze.
>
> Why is this necessary to add a freeze mechanism to kho_radix_tree?
> If it's a hard requirement of mshv maybe the freeze part should be handled
> there?

Good feedback. It's a safety-net so we do not accidentally donate pages 
without being able to track them. Thought it might be a good generic 
feature. Let me keep it in the MSHV driver.

>> Patch 13:      Radix tree freeze and del_key() error reporting
>
> del_key() error reporting sounds like something we'd want to avoid.
> del_key() is called on "freeing" path and during error handling, it would
> be hard if at all possible to deal with errors from del_key().

I hear you. Stating "yeah, it can only really fail if the key isn't there, 
or it's frozen, but not due to other things, so don't bother to check the 
return code if you are sure" is an odd contract. With the freeze-logic 
moving into MSHV, will revert to no-error.

>> Patch 19:      Export kexec_in_progress for modules
>
> Isn't there another way to differentiate kexec reboot?

I could not find one, unfortunately.

> Sincerely yours,
> Mike.

Best,
Jork