From patchwork Wed Nov 23 09:24:08 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 9442793 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0C08A6075F for ; Wed, 23 Nov 2016 09:26:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E34F720499 for ; Wed, 23 Nov 2016 09:26:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D62C22094D; Wed, 23 Nov 2016 09:26:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5E47C20499 for ; Wed, 23 Nov 2016 09:26:27 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1c9Tmp-0000hh-HX; Wed, 23 Nov 2016 09:24:15 +0000 Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1c9Tmo-0000ha-2D for xen-devel@lists.xenproject.org; Wed, 23 Nov 2016 09:24:14 +0000 Received: from [85.158.139.211] by server-2.bemta-5.messagelabs.com id 29/2F-08512-D3065385; Wed, 23 Nov 2016 09:24:13 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrOIsWRWlGSWpSXmKPExsXS6fjDS9c6wTT C4O4PU4vvWyYzOTB6HP5whSWAMYo1My8pvyKBNaNjUR9rwTO2ivvfT7A0ML5j6WLk5BASyJNY 82UGkM3BwStgJ9Hdxw4SlhAwlHj6/jobiM0ioCoxsfkaK4jNJqAu0fZsO5gtIiAt0T+nHaiei 4NZYCWjxN+DH8ASwgKWErPm9LNDzLeTaN28gBHE5hSwlzh8socRYpegxN8dwiBhZgEtiYe/br FA2NoSyxa+ZgYpYQaav/wfxwRGvlkIDbOQNMxC0jALoWEBI8sqRo3i1KKy1CJdIwO9pKLM9Iy S3MTMHF1DA1O93NTi4sT01JzEpGK95PzcTYzA4KtnYGDcwdg42+8QoyQHk5Iob7yDaYQQX1J+ SmVGYnFGfFFpTmrxIUYZDg4lCd6QeKCcYFFqempFWmYOMA5g0hIcPEoivPwgad7igsTc4sx0i NQpRmOON7tePmDieLf53QMmIZa8/LxUKXHeNSClAiClGaV5cINg8XmJUVZKmJeRgYFBiKcgtS g3swRV/hWjOAejkjDvwjigKTyZeSVw+14BncIEdIrkN2OQU0oSEVJSDYxdt9lWdvIxV1wsl1q hyTEnIPpuvVarnoSDWGByrPmNZfkRj9PfSU3b1frF6l/mGReFZ9df1zBN8b1Qrh+5zGTR4dmy fMXlExOXvS3beyy9ee0q2zULVBmYn4W+YjOZUrGGbUP71Flyt4O7RVYENna3Riw0vXYk8bnDv L+zHdPfBjWYrRf8HqHEUpyRaKjFXFScCADXAeQ3ygIAAA== X-Env-Sender: JBeulich@suse.com X-Msg-Ref: server-3.tower-206.messagelabs.com!1479893049!68132550!1 X-Originating-IP: [137.65.248.74] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 9.0.16; banners=-,-,- X-VirusChecked: Checked Received: (qmail 3862 invoked from network); 23 Nov 2016 09:24:11 -0000 Received: from prv-mh.provo.novell.com (HELO prv-mh.provo.novell.com) (137.65.248.74) by server-3.tower-206.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 23 Nov 2016 09:24:11 -0000 Received: from INET-PRV-MTA by prv-mh.provo.novell.com with Novell_GroupWise; Wed, 23 Nov 2016 02:24:09 -0700 Message-Id: <58356E480200007800121296@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.2.1 Date: Wed, 23 Nov 2016 02:24:08 -0700 From: "Jan Beulich" To: References: <58356D610200007800121289@prv-mh.provo.novell.com> In-Reply-To: <58356D610200007800121289@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Disposition: inline Cc: anthony.perard@citrix.com, xen-devel , Paul Durrant , Stefano Stabellini Subject: [Xen-devel] [PATCH 1/3] xen: fix quad word bufioreq handling X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP We should not consume the second slot if it didn't get written yet. Normal writers - i.e. Xen - would not update write_pointer between the two writes, but the page may get fiddled with by the guest itself, and we're better off entering an infinite loop in that case. Reported-by: yanghongke Signed-off-by: Jan Beulich --- TBD: Alternatively we could call e.g. hw_error() instead. --- a/xen-hvm.c +++ b/xen-hvm.c @@ -1021,6 +1021,9 @@ static int handle_buffered_iopage(XenIOS xen_rmb(); qw = (req.size == 8); if (qw) { + if (rdptr + 1 == wrptr) { + break; + } buf_req = &buf_page->buf_ioreq[(rdptr + 1) % IOREQ_BUFFER_SLOT_NUM]; req.data |= ((uint64_t)buf_req->data) << 32;