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=-7.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 1947DC433E1 for ; Thu, 6 Aug 2020 12:01:27 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 EBF1022D37 for ; Thu, 6 Aug 2020 12:01:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EBF1022D37 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k3e5W-0005S4-NQ; Thu, 06 Aug 2020 11:29:34 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1k3e5U-0005Rz-JP for xen-devel@lists.xenproject.org; Thu, 06 Aug 2020 11:29:32 +0000 X-Inumbo-ID: a1f2031a-9104-4c36-9eac-0dd4c7461e03 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id a1f2031a-9104-4c36-9eac-0dd4c7461e03; Thu, 06 Aug 2020 11:29:31 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id E8A23ABE9; Thu, 6 Aug 2020 11:29:47 +0000 (UTC) Subject: Re: [RFC PATCH V1 04/12] xen/arm: Introduce arch specific bits for IOREQ/DM features To: Julien Grall References: <1596478888-23030-1-git-send-email-olekstysh@gmail.com> <1596478888-23030-5-git-send-email-olekstysh@gmail.com> <11eaa2f0-84c7-5972-d14c-4cb02458e882@xen.org> <3ee50c66-8761-6c86-3fab-a4c23622d2b8@gmail.com> From: Jan Beulich Message-ID: Date: Thu, 6 Aug 2020 13:29:32 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , Wei Liu , Andrew Cooper , Ian Jackson , George Dunlap , Oleksandr , Oleksandr Tyshchenko , Julien Grall , xen-devel@lists.xenproject.org, Daniel De Graaf , Volodymyr Babchuk Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 06.08.2020 13:08, Julien Grall wrote: > On 05/08/2020 20:30, Oleksandr wrote: >> I was thinking how to split handle_hvm_io_completion() >> gracefully but I failed find a good solution for that, so decided to add >> two stubs (msix_write_completion and handle_realmode_completion) on Arm. >> I could add a comment describing why they are here if appropriate. But >> if you think they shouldn't be called from the common code in any way, I >> will try to split it. > > I am not entirely sure what msix_write_completion is meant to do on x86. > Is it dealing with virtual MSIx? Maybe Jan, Roger or Paul could help? Due to the split brain model of handling PCI pass-through (between Xen and qemu), a guest writing to an MSI-X entry needs this write handed to qemu, and upon completion of the write there Xen also needs to take some extra action. Jan