Re: [PATCH v1 1/1] KVM: s390/mm: Properly reset no-dat

From: Christian Borntraeger
Date: Thu Nov 09 2023 - 08:11:58 EST


Am 09.11.23 um 13:36 schrieb Claudio Imbrenda:
When the CMMA state needs to be reset, the no-dat bit also needs to be
reset. Failure to do so could cause issues in the guest, since the
guest expects the bit to be cleared after a reset.

This happens during reset of a guest (or whenever QEMU calls the CLR_CMMA thingi).
I think after reset a normal Linux guest has no DAT tables and very likely
a cpu reset (with explicit full guest flush) will happen. It will very likely
also set the CMMA state during boot before setting up its DAT tables.
So for the normal reboot this should be ok. But I can imagine cases that would
not be ok. So maybe add cc stable?