Subject: Re: [PATCH 2/3] powerpc/pseries/vas: Add VAS migration handler

From: Nathan Lynch <[email-masked]>
Date: Tue, 01 Feb 2022 10:12:47 -0600

Haren Myneni <[email-masked]> writes:
> On Mon, 2022-01-31 at 10:37 -0600, Nathan Lynch wrote:
>> Haren Myneni <[email-masked]> writes:
>> > Since the VAS windows belong to the VAS hardware resource, the
>> > hypervisor expects the partition to close them on source partition
>> > and reopen them after the partition migrated on the destination
>> > machine.
>> 
>> Not clear to me what "expects" really means here. Would it be
>> accurate to say "requires" instead? If the OS fails to close the
>> windows before suspend, what happens?
>
> I will change it to 'requires' - These VAS windows have to be closed
> before migration so that these windows / credits will be available to
> other LPARs on the source machine.

I'll rephrase.

I want to know whether the architecture (PAPR or whichever doc) imposes
a requirement on the OS (i.e. using words like "must") to close the
windows, or does it merely make a recommendation ("should"), or is it
silent on the subject?

In your testing, if Linux has windows open at the time of calling
ibm,suspend-me, does the call fail or succeed?