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: 9442789 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 C6A3D6075F for ; Wed, 23 Nov 2016 09:24:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A9BCB20410 for ; Wed, 23 Nov 2016 09:24:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9BABB206AF; Wed, 23 Nov 2016 09:24:43 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 34C2620410 for ; Wed, 23 Nov 2016 09:24:43 +0000 (UTC) Received: from localhost ([::1]:60392 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9TnG-0002bm-CJ for patchwork-qemu-devel@patchwork.kernel.org; Wed, 23 Nov 2016 04:24:42 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36995) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9Tmo-0002am-BA for qemu-devel@nongnu.org; Wed, 23 Nov 2016 04:24:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c9Tml-0005f4-7M for qemu-devel@nongnu.org; Wed, 23 Nov 2016 04:24:14 -0500 Received: from prv-mh.provo.novell.com ([137.65.248.74]:45192) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c9Tmk-0005dX-U5 for qemu-devel@nongnu.org; Wed, 23 Nov 2016 04:24:11 -0500 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 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 137.65.248.74 Subject: [Qemu-devel] [PATCH 1/3] xen: fix quad word bufioreq handling X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: anthony.perard@citrix.com, xen-devel , Paul Durrant , Stefano Stabellini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-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;