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=-6.7 required=3.0 tests=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 64CA1C73C7C for ; Wed, 10 Jul 2019 08:21:41 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2DFFD20693 for ; Wed, 10 Jul 2019 08:21:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2DFFD20693 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59020 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hl7rA-0005ri-E6 for qemu-devel@archiver.kernel.org; Wed, 10 Jul 2019 04:21:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52879) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hl7qO-0005PJ-W0 for qemu-devel@nongnu.org; Wed, 10 Jul 2019 04:20:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hl7qN-0002sP-5g for qemu-devel@nongnu.org; Wed, 10 Jul 2019 04:20:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46354) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hl7qM-0002pe-SE; Wed, 10 Jul 2019 04:20:51 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9A988300602A; Wed, 10 Jul 2019 08:20:47 +0000 (UTC) Received: from gondolin (dhcp-192-232.str.redhat.com [10.33.192.232]) by smtp.corp.redhat.com (Postfix) with ESMTP id D16321001B02; Wed, 10 Jul 2019 08:20:43 +0000 (UTC) Date: Wed, 10 Jul 2019 10:20:41 +0200 From: Cornelia Huck To: Collin Walling Message-ID: <20190710102041.6be31940.cohuck@redhat.com> In-Reply-To: <0dd71cfe-a9e9-7ac3-523e-065f05479a57@linux.ibm.com> References: <20190708125433.16927-1-cohuck@redhat.com> <20190708125433.16927-2-cohuck@redhat.com> <58b28817-58e5-1cba-6f71-a35093be5cb6@de.ibm.com> <0dd71cfe-a9e9-7ac3-523e-065f05479a57@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Wed, 10 Jul 2019 08:20:48 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [qemu-s390x] [PATCH for-4.1 1/2] s390x/pci: add some fallthrough annotations X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Hildenbrand , Stefan Weil , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 9 Jul 2019 18:55:34 -0400 Collin Walling wrote: > On 7/8/19 9:23 AM, Christian Borntraeger wrote: > > > > > > On 08.07.19 14:54, Cornelia Huck wrote: > >> According to the comment, the bits are supposed to accumulate. > >> > >> Reported-by: Stefan Weil > >> Fixes: 5d1abf234462 ("s390x/pci: enforce zPCI state checking") > >> Signed-off-by: Cornelia Huck > > > > This patch does not change behaviour, so it is certainly not wrong. > > > > So lets have a look at if the bug report was actually a real bug or > > just a missing annotation. > > > >> --- > >> hw/s390x/s390-pci-inst.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c > >> index 61f30b8e55d2..00235148bed7 100644 > >> --- a/hw/s390x/s390-pci-inst.c > >> +++ b/hw/s390x/s390-pci-inst.c > >> @@ -1209,8 +1209,10 @@ int stpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar, > >> * FH Enabled bit is set to one in states of ENABLED, BLOCKED or ERROR. */ > >> case ZPCI_FS_ERROR: > >> fib.fc |= 0x20; > >> + /* fallthrough */ > > > > This is correct, in case of an error we are also blocked. > > > > Agreed. This is definitely correct based on our architecture. > > >> case ZPCI_FS_BLOCKED: > >> fib.fc |= 0x40; > >> + /* fallthrough */ > > > > I think this is also correct, but it would be good if Collin could verify. > > > > I failed to find anything to support setting the function control > enabled bit when the function state is in error / blocked. I'm > assuming this might be some QEMU hack to get things working? I'll have > to dive further to understand why this was done this way, as it doesn't > align with how the s390x architecture is documented. It's confusing. Might this also be a real issue? Not matching the architecture is not a good sign... > > Functionally, this doesn't change anything... so I'll at least give it > an ACK for now and investigate this further. I prefer to hold off on this patch for now, unless we're really sure that the code does not have a problem here. Actually documenting something that might be wrong does not sound like the right thing to do :/ > > >> case ZPCI_FS_ENABLED: > >> fib.fc |= 0x80; > >> if (pbdev->iommu->enabled) { > >> > > > > > > Acked-by: Collin Walling > > Side note: is there somewhere that I could access this bug report? :) It's the build log with the extra warnings in https://qemu.weilnetz.de/results/build-20190708.txt (referenced in <591d71a5-5b10-ab22-4751-01da8613d84c@weilnetz.de> on qemu-devel).