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 B22BDC4321D for ; Wed, 22 Aug 2018 11:13:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5AAED214FF for ; Wed, 22 Aug 2018 11:13:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5AAED214FF 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 S1728829AbeHVOhl (ORCPT ); Wed, 22 Aug 2018 10:37:41 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45446 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728518AbeHVOhl (ORCPT ); Wed, 22 Aug 2018 10:37:41 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4FBF74023ECB; Wed, 22 Aug 2018 11:13:12 +0000 (UTC) Received: from [10.36.117.196] (ovpn-117-196.ams2.redhat.com [10.36.117.196]) by smtp.corp.redhat.com (Postfix) with ESMTP id D2A282166BA1; Wed, 22 Aug 2018 11:13:10 +0000 (UTC) Subject: Re: [PATCH v1] KVM: s390: store DXC/VXC in fpc on DATA/Vector-processing exceptions To: Janosch Frank , linux-kernel@vger.kernel.org Cc: linux-s390@vger.kernel.org, Heiko Carstens , Martin Schwidefsky , Cornelia Huck , Christian Borntraeger , Hendrik Brueckner References: <20180822095310.29145-1-david@redhat.com> <02f9379d-d20d-8b69-94b9-959f46490a26@linux.ibm.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: <02f9379d-d20d-8b69-94b9-959f46490a26@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 22 Aug 2018 11:13:12 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 22 Aug 2018 11:13:12 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.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 22.08.2018 12:31, Janosch Frank wrote: > On 22.08.2018 11:53, David Hildenbrand wrote: >> When DATA exceptions and vector-processing exceptions (program interrupts) >> are injected, the DXC/VXC is also to be stored in the fpc, if AFP is >> enabled in CR0. >> >> This can happen inside KVM when reinjecting an interrupt during program >> interrupt intercepts. These are triggered for example when debugging the >> guest (concurrent PER events result in an intercept instead of an >> injection of such interrupts). >> >> Signed-off-by: David Hildenbrand >> --- >> >> Only compile-tested. > > It baffles me that AFP is still a thing in zArch mode. I would have > expected it to be a default 1. But then again, I just found out about it. > > POP checks out: > Reviewed-by: Janosch Frank > > >> >> arch/s390/include/asm/ctl_reg.h | 1 + >> arch/s390/kvm/interrupt.c | 8 ++++++++ >> 2 files changed, 9 insertions(+) >> >> diff --git a/arch/s390/include/asm/ctl_reg.h b/arch/s390/include/asm/ctl_reg.h >> index 4600453536c2..88f3f14baee9 100644 >> --- a/arch/s390/include/asm/ctl_reg.h >> +++ b/arch/s390/include/asm/ctl_reg.h >> @@ -11,6 +11,7 @@ >> #include >> >> #define CR0_CLOCK_COMPARATOR_SIGN _BITUL(63 - 10) >> +#define CR0_AFP_REGISTER_CONTROL _BITUL(63 - 45) >> #define CR0_EMERGENCY_SIGNAL_SUBMASK _BITUL(63 - 49) >> #define CR0_EXTERNAL_CALL_SUBMASK _BITUL(63 - 50) >> #define CR0_CLOCK_COMPARATOR_SUBMASK _BITUL(63 - 52) >> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c >> index fcb55b02990e..5b5754d8f460 100644 >> --- a/arch/s390/kvm/interrupt.c >> +++ b/arch/s390/kvm/interrupt.c >> @@ -765,6 +765,14 @@ static int __must_check __deliver_prog(struct kvm_vcpu *vcpu) >> break; >> case PGM_VECTOR_PROCESSING: >> case PGM_DATA: >> + if (vcpu->arch.sie_block->gcr[0] & CR0_AFP_REGISTER_CONTROL) { >> + /* make sure the new fpc will be lazily loaded */ >> + save_fpu_regs(); >> + /* the DXC/VXC cannot make the fpc invalid */ >> + current->thread.fpu.fpc &= ~0xff00u; >> + current->thread.fpu.fpc |= (pgm_info.data_exc_code << 8) >> + & 0xff00u; > > Everything except that byte should be 0 anyway when it comes from > lowcore, why do you mask? User space can inject such an interrupt and could therefore set reserved bits, leading to a crash (fpc invalid when loaded). E.g. via kvm_s390_set_irq_state(). As of now, DXC/VXC is always 1byte. The other ones are to be stored as 0. (what we expect to always hold for now but user space can do crazy things) Thanks! > >> + } >> rc = put_guest_lc(vcpu, pgm_info.data_exc_code, >> (u32 *)__LC_DATA_EXC_CODE); >> break; >> > > -- Thanks, David / dhildenb