From patchwork Tue Jun 20 13:47:54 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 9799577 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 EB39260329 for ; Tue, 20 Jun 2017 13:48:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ED445284B1 for ; Tue, 20 Jun 2017 13:48:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EBE5A284DA; Tue, 20 Jun 2017 13:48:47 +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 A7E4F284B1 for ; Tue, 20 Jun 2017 13:48:46 +0000 (UTC) Received: from localhost ([::1]:48942 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dNJWO-00021Q-US for patchwork-qemu-devel@patchwork.kernel.org; Tue, 20 Jun 2017 09:48:44 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34131) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dNJVn-000217-5Q for qemu-devel@nongnu.org; Tue, 20 Jun 2017 09:48:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dNJVk-0008U3-E2 for qemu-devel@nongnu.org; Tue, 20 Jun 2017 09:48:07 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:32274) by eggs.gnu.org with esmtps (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71) (envelope-from ) id 1dNJVk-0008QO-6m; Tue, 20 Jun 2017 09:48:04 -0400 X-IronPort-AV: E=Sophos;i="5.39,364,1493683200"; d="scan'208";a="437138721" From: Paul Durrant To: , , Date: Tue, 20 Jun 2017 09:47:54 -0400 Message-ID: <20170620134756.9632-2-paul.durrant@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170620134756.9632-1-paul.durrant@citrix.com> References: <20170620134756.9632-1-paul.durrant@citrix.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 66.165.176.63 Subject: [Qemu-devel] [PATCH 1/3] xen-disk: only advertize feature-persistent if grant copy is not available 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 , Kevin Wolf , Paul Durrant , Stefano Stabellini , Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP If grant copy is available then it will always be used in preference to persistent maps. In this case feature-persistent should not be advertized to the frontend, otherwise it may needlessly copy data into persistently granted buffers. Signed-off-by: Paul Durrant --- Cc: Stefano Stabellini Cc: Anthony Perard Cc: Kevin Wolf Cc: Max Reitz --- hw/block/xen_disk.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index 3a22805fbc..9b06e3aa81 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -1023,11 +1023,18 @@ static int blk_init(struct XenDevice *xendev) blkdev->file_blk = BLOCK_SIZE; + blkdev->feature_grant_copy = + (xengnttab_grant_copy(blkdev->xendev.gnttabdev, 0, NULL) == 0); + + xen_pv_printf(&blkdev->xendev, 3, "grant copy operation %s\n", + blkdev->feature_grant_copy ? "enabled" : "disabled"); + /* fill info * blk_connect supplies sector-size and sectors */ xenstore_write_be_int(&blkdev->xendev, "feature-flush-cache", 1); - xenstore_write_be_int(&blkdev->xendev, "feature-persistent", 1); + xenstore_write_be_int(&blkdev->xendev, "feature-persistent", + !blkdev->feature_grant_copy); xenstore_write_be_int(&blkdev->xendev, "info", info); blk_parse_discard(blkdev); @@ -1202,12 +1209,6 @@ static int blk_connect(struct XenDevice *xendev) xen_be_bind_evtchn(&blkdev->xendev); - blkdev->feature_grant_copy = - (xengnttab_grant_copy(blkdev->xendev.gnttabdev, 0, NULL) == 0); - - xen_pv_printf(&blkdev->xendev, 3, "grant copy operation %s\n", - blkdev->feature_grant_copy ? "enabled" : "disabled"); - xen_pv_printf(&blkdev->xendev, 1, "ok: proto %s, ring-ref %d, " "remote port %d, local port %d\n", blkdev->xendev.protocol, blkdev->ring_ref,