From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8DC6C46470 for ; Wed, 8 Aug 2018 12:53:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C17F214DD for ; Wed, 8 Aug 2018 12:53:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5C17F214DD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727264AbeHHPNQ (ORCPT ); Wed, 8 Aug 2018 11:13:16 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58100 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726680AbeHHPNQ (ORCPT ); Wed, 8 Aug 2018 11:13:16 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DC27140241C3; Wed, 8 Aug 2018 12:53:40 +0000 (UTC) Received: from [10.36.117.83] (ovpn-117-83.ams2.redhat.com [10.36.117.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id 115751C72E; Wed, 8 Aug 2018 12:53:38 +0000 (UTC) Subject: Re: [PATCH RFC 2/2] KVM: s390: introduce and use KVM_REQ_VSIE_RESTART To: Cornelia Huck Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Martin Schwidefsky , Janosch Frank , Christian Borntraeger , Pierre Morel References: <20180807125131.3606-1-david@redhat.com> <20180807125131.3606-3-david@redhat.com> <20180808144733.507ba955.cohuck@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180808144733.507ba955.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 08 Aug 2018 12:53:40 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 08 Aug 2018 12:53:40 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'david@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.08.2018 14:47, Cornelia Huck wrote: > On Tue, 7 Aug 2018 14:51:31 +0200 > David Hildenbrand wrote: > >> When we change the crycb (or execution controls), we also have to make sure >> that the vSIE shadow datastructures properly consider the changed >> values before rerunning the vSIE. We can achieve that by simply using a >> VCPU request now. > > Is this actually a concrete problem right now, or does this only become > a real concern with vfio-ap? The use case I implemented is not a real problem right now, at least not in practice. In QEMU, s390_crypto_reset() triggers this code, but it is only called when all VCPUs are stopped (== no one in vSIE). So this change is the right thing to do ("who knows what user space does"), but not critical (we're only dealing with wrapping masks right now). It is a problem once we allow to access adapters (vfio-ap). > >> >> This has to be a synchronous request (== handled before entering the >> (v)SIE again). >> >> The request will make sure that the vSIE handler is left, and that the >> request will be processed (NOP), therefore forcing a reload of all >> vSIE data (including rebuilding the crycb) when re-entering the vSIE >> interception handler the next time. >> >> Signed-off-by: David Hildenbrand >> --- >> arch/s390/include/asm/kvm_host.h | 1 + >> arch/s390/kvm/kvm-s390.c | 7 ++++++- >> 2 files changed, 7 insertions(+), 1 deletion(-) > > Reviewed-by: Cornelia Huck > -- Thanks, David / dhildenb