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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]:34092 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kfIFN-0004HH-AQ for qemu-devel@archiver.kernel.org; Wed, 18 Nov 2020 02:51:21 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42342) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfIEA-0003kV-A4 for qemu-devel@nongnu.org; Wed, 18 Nov 2020 02:50:06 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:55341) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kfIE8-0007ij-9L for qemu-devel@nongnu.org; Wed, 18 Nov 2020 02:50:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605685803; 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=875ExDgujjG7x+qxkqbVrQhyIJWpSBtUawvueclUcWI=; b=U13MnSIUAPunrtdEqweFbpCEOOTrJv4GdGB/+Oae5DFSU3wPMFJbELiK0Zn3vcWB8kA8Kl ezhKp6k5NO4aiawJ0RqObwJ4k6maIxpBjsfZz6YdixU+Gq9guIi9+UFiV15p+m258ZA5HQ w63KRSW7n6O2M6s+PsWHm4x+dTC2oIE= 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-286-b1Mkw0bHNeCBGByUzx-mfw-1; Wed, 18 Nov 2020 02:49:59 -0500 X-MC-Unique: b1Mkw0bHNeCBGByUzx-mfw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 96C366D585; Wed, 18 Nov 2020 07:49:58 +0000 (UTC) Received: from gondolin (ovpn-113-132.ams2.redhat.com [10.36.113.132]) by smtp.corp.redhat.com (Postfix) with ESMTP id B708A5C1BB; Wed, 18 Nov 2020 07:49:49 +0000 (UTC) Date: Wed, 18 Nov 2020 08:49:47 +0100 From: Cornelia Huck To: Matthew Rosato Subject: Re: [PATCH for-5.2] s390x/pci: fix endianness issues Message-ID: <20201118084947.172002fe.cohuck@redhat.com> In-Reply-To: References: <20201117171340.1289659-1-cohuck@redhat.com> <6a1b2ba1-642a-9cee-4d7d-2c1e4ea826ed@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/17 19:41:43 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: Thomas Huth , Alex Williamson , Pierre Morel , David Hildenbrand , Richard Henderson , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 17 Nov 2020 14:49:53 -0500 Matthew Rosato wrote: > On 11/17/20 2:21 PM, Thomas Huth wrote: > > On 17/11/2020 18.13, Cornelia Huck wrote: > >> zPCI control blocks are big endian, we need to take care that we > >> do proper accesses in order not to break tcg guests on little endian > >> hosts. > >> > >> Fixes: 28dc86a07299 ("s390x/pci: use a PCI Group structure") > >> Fixes: 9670ee752727 ("s390x/pci: use a PCI Function structure") > >> Fixes: 1e7552ff5c34 ("s390x/pci: get zPCI function info from host") > > > > This fixes the problem with my old Fedora 28 under TCG, too, but... do we > > really want to store this information in big endian on the QEMU side (e.g. > > in the QTAILQ lists)? ... that smells like trouble again in the future... > > > > I think it would be better if we rather replace all those memcpy() functions > > in the patches that you cited in the "Fixes:" lines above with code that > > changes the endianess when we copy the date from QEMU space to guest space > > and vice versa. What do you think? > > Hmm, that's actually a fair point... Such an approach would have the > advantage of avoiding weird lines like the following: > > memory_region_add_subregion(&pbdev->iommu->mr, > - pbdev->pci_group->zpci_group.msia, > + ldq_p(&pbdev->pci_group->zpci_group.msia), > &pbdev->msix_notify_mr); > > > And would keep messing with endianness largely contained to the code > that handles CLPs. It does take away the niceness of being able to > gather the CLP response in one fell memcpy but... It's not like these > are done very often (device init). > Not opposed to it, can try to put a patch together and see what it looks like. As long as we get this into 5.2 :)