From nobody Sun Feb 8 16:30:48 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass(p=none dis=none) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; t=1657925510; cv=none; d=zohomail.com; s=zohoarc; b=cvOxER69gPjoNlbauYZPzkQ/vmPV3RnwNx3D3v84BIIAbqSVJvRvx7xdmNT+znpGyTlTN1NeZThHoCxlZbf9j4oNs3Jgp5XI28qaU9Q6iR6zYUATvuJF0lfCX6FVyYdfNuu0HbfN7y2lOpcfsnss/MsWDDVyHBFGpNWl9jlSMLQ= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1657925510; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=h4MCYvsqnFmMTtsQGU9rhIDUKaHK8py2jjweYjlSYWg=; b=eGnoil9y46u9LeikYqiAUTU7mbXxphs3M9coSCdW0kMevRgdsKZbzDS3qs8W8f6V86goHFYo+GWWMQzAfqDxuUjPlAj9W6c9OtKLzgisrE7TjdyKCQeKlHUnfXqWDLvrn8QrMvbgJ/wQs7XWdIAE6ZduPkmyZHEdVyvwcUS6Jco= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1657925510052763.3478121191798; Fri, 15 Jul 2022 15:51:50 -0700 (PDT) Received: from list by lists.xenproject.org with outflank-mailman.368573.599925 (Exim 4.92) (envelope-from ) id 1oCU9c-0005YD-Ha; Fri, 15 Jul 2022 22:51:24 +0000 Received: by outflank-mailman (output) from mailman id 368573.599925; Fri, 15 Jul 2022 22:51:24 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1oCU9c-0005Y6-F0; Fri, 15 Jul 2022 22:51:24 +0000 Received: by outflank-mailman (input) for mailman id 368573; Fri, 15 Jul 2022 22:51:23 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1oCU9b-0005Xu-5q for xen-devel@lists.xenproject.org; Fri, 15 Jul 2022 22:51:23 +0000 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id a4a123c4-0490-11ed-924f-1f966e50362f; Sat, 16 Jul 2022 00:51:21 +0200 (CEST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B9BCFB82EF2; Fri, 15 Jul 2022 22:51:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E7B9C341C6; Fri, 15 Jul 2022 22:51:17 +0000 (UTC) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: a4a123c4-0490-11ed-924f-1f966e50362f DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657925478; bh=dlKaQtwg6yYz18rR7yrtedCSXkIPHob7qvry1GivQwU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zfee0JPaAo7oMHjphPshW1SCisXCB26lmUDf4+N5Lfa3ZXWP/1h9AYnrlFDyOnNGa 8CZCtlA0YcgiyS66d8rMWfTaDRK7BIaeNQsTXBSIJBWZcdIXsm6wJMbEebhJ0AHuHQ E7ljrx5Vc/3IEsYX/sJTdT+2WNJtr8q4TKoP2iBaDXH8ARh4/17mMXAxgC2RbBf/K2 d5QfzG48sV1dKnSkxRUMsXwBfgW5WnZrxs8QqGVmfjqa477pJcj5R1aKWjoD/dg20e pGpPpMEEltiWk3QRupHXiLvkIvon2u4J27h7ydm+P58QnbX7Wq0/CPCdq771cV88PS wvmYZSwRdGvyQ== From: SeongJae Park To: roger.pau@citrix.com Cc: axboe@kernel.dk, boris.ostrovsky@oracle.com, jgross@suse.com, olekstysh@gmail.com, andrii.chepurnyi82@gmail.com, mheyne@amazon.de, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, SeongJae Park Subject: [PATCH v4 1/3] xen-blkback: fix persistent grants negotiation Date: Fri, 15 Jul 2022 22:51:06 +0000 Message-Id: <20220715225108.193398-2-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220715225108.193398-1-sj@kernel.org> References: <20220715225108.193398-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @kernel.org) X-ZM-MESSAGEID: 1657925511634100001 Content-Type: text/plain; charset="utf-8" Persistent grants feature can be used only when both backend and the frontend supports the feature. The feature was always supported by 'blkback', but commit aac8a70db24b ("xen-blkback: add a parameter for disabling of persistent grants") has introduced a parameter for disabling it runtime. To avoid the parameter be updated while being used by 'blkback', the commit caches the parameter into 'vbd->feature_gnt_persistent' in 'xen_vbd_create()', and then check if the guest also supports the feature and finally updates the field in 'connect_ring()'. However, 'connect_ring()' could be called before 'xen_vbd_create()', so later execution of 'xen_vbd_create()' can wrongly overwrite 'true' to 'vbd->feature_gnt_persistent'. As a result, 'blkback' could try to use 'persistent grants' feature even if the guest doesn't support the feature. This commit fixes the issue by moving the parameter value caching to 'xen_blkif_alloc()', which allocates the 'blkif'. Because the struct embeds 'vbd' object, which will be used by 'connect_ring()' later, this should be called before 'connect_ring()' and therefore this should be the right and safe place to do the caching. Fixes: aac8a70db24b ("xen-blkback: add a parameter for disabling of persist= ent grants") Cc: # 5.10.x Signed-off-by: Maximilian Heyne Signed-off-by: SeongJae Park --- drivers/block/xen-blkback/xenbus.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback= /xenbus.c index 97de13b14175..16c6785d260c 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -157,6 +157,11 @@ static int xen_blkif_alloc_rings(struct xen_blkif *blk= if) return 0; } =20 +/* Enable the persistent grants feature. */ +static bool feature_persistent =3D true; +module_param(feature_persistent, bool, 0644); +MODULE_PARM_DESC(feature_persistent, "Enables the persistent grants featur= e"); + static struct xen_blkif *xen_blkif_alloc(domid_t domid) { struct xen_blkif *blkif; @@ -181,6 +186,8 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid) __module_get(THIS_MODULE); INIT_WORK(&blkif->free_work, xen_blkif_deferred_free); =20 + blkif->vbd.feature_gnt_persistent =3D feature_persistent; + return blkif; } =20 @@ -472,12 +479,6 @@ static void xen_vbd_free(struct xen_vbd *vbd) vbd->bdev =3D NULL; } =20 -/* Enable the persistent grants feature. */ -static bool feature_persistent =3D true; -module_param(feature_persistent, bool, 0644); -MODULE_PARM_DESC(feature_persistent, - "Enables the persistent grants feature"); - static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, unsigned major, unsigned minor, int readonly, int cdrom) @@ -520,8 +521,6 @@ static int xen_vbd_create(struct xen_blkif *blkif, blki= f_vdev_t handle, if (bdev_max_secure_erase_sectors(bdev)) vbd->discard_secure =3D true; =20 - vbd->feature_gnt_persistent =3D feature_persistent; - pr_debug("Successful creation of handle=3D%04x (dom=3D%u)\n", handle, blkif->domid); return 0; --=20 2.25.1