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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 979B4C282DD for ; Wed, 8 Jan 2020 17:52:59 +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 683A12067D for ; Wed, 8 Jan 2020 17:52:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="ww6Na8zO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 683A12067D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47488 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipFVq-0000bU-Fk for qemu-devel@archiver.kernel.org; Wed, 08 Jan 2020 12:52:58 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:49594) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ipFUe-0007Cr-LV for qemu-devel@nongnu.org; Wed, 08 Jan 2020 12:51:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ipFUd-0002nM-Ij for qemu-devel@nongnu.org; Wed, 08 Jan 2020 12:51:44 -0500 Received: from mail-ot1-x343.google.com ([2607:f8b0:4864:20::343]:40988) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1ipFUd-0002ly-CA for qemu-devel@nongnu.org; Wed, 08 Jan 2020 12:51:43 -0500 Received: by mail-ot1-x343.google.com with SMTP id r27so4394613otc.8 for ; Wed, 08 Jan 2020 09:51:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EumLXX1XF7D/XgT2FUPJGk5UmCAhXwl1l2QbIwTe7x8=; b=ww6Na8zOQ0Achy4Zm3ObKx+J/XtmBQSktzmMmpNddc/+9aeSV+oEq/F7q8HoWZmX9A kYWhmZO3F3GkK0099+SYh6hoLsAD2Nu2wyJ7Krknuh88PoVPbRr00b2tP/xtrCQ+Xyv4 YBhpZsvVQCSpIJx8/UFa1Z1XvAAzbNeZmxmEulLGSm0ggyc+oFthKlOzVGIwsIHYQWfq W7Av51d0QymQ7WAPElg2ZzbSG39opWhO3um9ikzbiXM5Il/gRaod8au1ouyI3YYAvpJG g8HJwZrbzN0niA4KW9xhG8ktXx2B+ajAgHq5g4reSgD1Q3u7UKwGcfH0T8D0Rqb6kFpo oEeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EumLXX1XF7D/XgT2FUPJGk5UmCAhXwl1l2QbIwTe7x8=; b=cCK32aZR/wi1J1hsHLPtuqSJ6EsKcM19GXWTpMOfsVA/1t8wjJjPiM73Ej10UDbRd7 zF3MvUav9HU43eKfL87kmg+wrkpmE3APpMxmvlRIM/ZmSqewqTIWzBzqVq6u0kMhIt9X 4wch6WfN5bVxYJnPnwmOp/edxhOSLzrUTTEKRbaQBXiAMBP7l1OZPCmRZXhZd/T3QtGw Cp42yw7JO7kdc0WuOZJOUX75N0gqtB4y7nnJb6iOO3L+IFTy0TANZdxbZ6v3Fk+vnUNo 3gCRhEbm2lSnPhQBdjXNCMQa4SQ2sv40YSlwlwjblv1BfwGXpo82mni8nqrsFLsmV9/r 1COQ== X-Gm-Message-State: APjAAAVEzAB4zmD5Jqwr4IpMryYYLcjV6T6GnnCBHDNKP/nw1vDKrJh4 yRBZ0i5fLHt456jfsUEyx1oM1lXBEb3doNUTuD4v6A== X-Google-Smtp-Source: APXvYqzCD22PBgif05TUFv5KWT98RQsAn7VMZDlw1jfRa7dq8WIvkq5Zohrnl15Oa2K3R1bXGKIQzOnZlMViuNSko+c= X-Received: by 2002:a05:6830:13d3:: with SMTP id e19mr5127266otq.135.1578505901742; Wed, 08 Jan 2020 09:51:41 -0800 (PST) MIME-Version: 1.0 References: <20200108161618.221116-1-afscoelho@gmail.com> In-Reply-To: <20200108161618.221116-1-afscoelho@gmail.com> From: Peter Maydell Date: Wed, 8 Jan 2020 17:51:30 +0000 Message-ID: Subject: Re: [PATCH] virtio: Prevent double swap due to target pre 1.0 VirtIO To: Andre Silva Content-Type: text/plain; charset="UTF-8" X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::343 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: QEMU Developers , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 8 Jan 2020 at 16:20, Andre Silva wrote: > > Remove the bswap function calls after reading and before writing > memory bytes in virtio_pci_config_read and virtio_pci_config_write > because they are reverting back an already swapped bytes Is "because we wrote it via virtio_pci_config_write" really the only way that the data read by virtio_pci_config_read is ever set or updated ? thanks -- PMM