From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [RFC/PATCH v3 04/16] s390/mm: add gmap PMD invalidation notification Date: Wed, 14 Feb 2018 11:42:14 +0100 Message-ID: References: <1518168864-147803-1-git-send-email-frankja@linux.vnet.ibm.com> <1518168864-147803-5-git-send-email-frankja@linux.vnet.ibm.com> <38c32f80-9225-8e71-7a8a-aa759cdbbfc7@redhat.com> <5fb02c01-bbda-bdd7-eb54-8e8ee525093c@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5fb02c01-bbda-bdd7-eb54-8e8ee525093c@linux.vnet.ibm.com> Content-Language: en-US Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Janosch Frank , kvm@vger.kernel.org Cc: schwidefsky@de.ibm.com, borntraeger@de.ibm.com, dominik.dingel@gmail.com, linux-s390@vger.kernel.org List-ID: >>>> That's interesting, because the SIE can now suddenly work on these >>>> PGSTEs, e.g. not leading to intercepts on certain events (like setting >>>> storage keys). >>>> >>>> How is that intended to be handled? I assume we would somehow have to >>>> forbid the SIE from making use of the PGSTE. But that involves clearing >>>> certain interception controls, which might be problematic. >>> >>> Well, cmma is disabled and storage keys should only be a problem, when >>> the pte is invalid without the pgste lock, which should never be the >>> case for split pmds. >>> >> >> Are you sure? Because the SIE would suddenly stark working on guest >> storage keys stored in the PGSTE if I am not mistaking? So I would >> assume that there would have to be some kind of a sync. >> >> But I don't have any documentation at hand, so i can't tell :) >> > > The pgste lock is that sync and as the gmap is the only way to get to > the pte, we don't have any ptes invalid without the lock. Also > set_guest_storage_keys will find a (userspace) pmd and do a hardware > sske, like it is supposed to. What happens according to the documentation in the following cases: The HW has the storage-key facility enabled and a SKEY operation (ISKE, RRBE, SSKE) hits a huge page: a) Generates an intercept b) Uses the real machine storage key (as there are no pgste) -- Thanks, David / dhildenb