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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E33D5C47247 for ; Tue, 5 May 2020 08:29:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C07D6206CC for ; Tue, 5 May 2020 08:29:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="a+ocrsWg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728567AbgEEI3F (ORCPT ); Tue, 5 May 2020 04:29:05 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:35205 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728556AbgEEI3E (ORCPT ); Tue, 5 May 2020 04:29:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588667343; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tEMlfqWVFKOqZSe1ugGA+hpEFb+mKSy4G8wcXNM339E=; b=a+ocrsWg11yqEHSsrYgCGXVoFZq1OTYLWKCDgx5wwc3EO2Kx8j/qg5ly+faqJz+TcAUn0+ jfb0p4OJNmmaNA9OacdrRJKIj08LhltnooLVIA/llKihwkbPXgroXY8nHTh6BS8PRx++hr AR43mJoEWCRW7HCqGCJzbs2p99uY1bo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-437-KUyFRwldOyqJFNFqfSXowQ-1; Tue, 05 May 2020 04:28:59 -0400 X-MC-Unique: KUyFRwldOyqJFNFqfSXowQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 65A9A107ACF5; Tue, 5 May 2020 08:28:58 +0000 (UTC) Received: from gondolin (ovpn-112-219.ams2.redhat.com [10.36.112.219]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0A3735D9D3; Tue, 5 May 2020 08:28:53 +0000 (UTC) Date: Tue, 5 May 2020 10:21:39 +0200 From: Cornelia Huck To: Christian Borntraeger Cc: Janosch Frank , KVM , David Hildenbrand , linux-s390 , Qian Cai , Pierre Morel , Tony Krowiak Subject: Re: [PATCH] KVM: s390: Remove false WARN_ON_ONCE for the PQAP instruction Message-ID: <20200505101739.137393dc.cohuck@redhat.com> In-Reply-To: References: <20200505073525.2287-1-borntraeger@de.ibm.com> <20200505095332.528254e5.cohuck@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 5 May 2020 09:55:36 +0200 Christian Borntraeger wrote: > On 05.05.20 09:53, Cornelia Huck wrote: > > On Tue, 5 May 2020 09:35:25 +0200 > > Christian Borntraeger wrote: > > > >> In LPAR we will only get an intercept for FC==3 for the PQAP > >> instruction. Running nested under z/VM can result in other intercepts as > >> well, for example PQAP(QCI). So the WARN_ON_ONCE is not right. Let > >> us simply remove it. > > > > While I agree with removing the WARN_ON_ONCE, I'm wondering why z/VM > > gives us intercepts for those fcs... is that just a result of nesting > > (or the z/VM implementation), or is there anything we might want to do? > > Yes nesting. > The ECA bit for interpretion is an effective one. So if the ECA bit is off > in z/VM (no crypto cards) our ECA bit is basically ignored as these bits > are ANDed. Ok, that makes sense, even if it is rather ugly. With the comment tweaked, Reviewed-by: Cornelia Huck > I asked Tony to ask the z/VM team if that is the case here. > > > > >> > >> Cc: Pierre Morel > >> Cc: Tony Krowiak > >> Reported-by: Qian Cai > >> Signed-off-by: Christian Borntraeger > >> --- > >> arch/s390/kvm/priv.c | 4 +++- > >> 1 file changed, 3 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c > >> index 69a824f9ef0b..bbe46c6aedbf 100644 > >> --- a/arch/s390/kvm/priv.c > >> +++ b/arch/s390/kvm/priv.c > >> @@ -626,10 +626,12 @@ static int handle_pqap(struct kvm_vcpu *vcpu) > >> * available for the guest are AQIC and TAPQ with the t bit set > >> * since we do not set IC.3 (FIII) we currently will only intercept > >> * the AQIC function code. > >> + * Note: running nested under z/VM can result in intercepts, e.g. > > > > s/intercepts/intercepts for other function codes/ > > > >> + * for PQAP(QCI). We do not support this and bail out. > >> */ > >> reg0 = vcpu->run->s.regs.gprs[0]; > >> fc = (reg0 >> 24) & 0xff; > >> - if (WARN_ON_ONCE(fc != 0x03)) > >> + if (fc != 0x03) > >> return -EOPNOTSUPP; > >> > >> /* PQAP instruction is allowed for guest kernel only */ > > >