From patchwork Thu Nov 25 13:53:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12639211 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F2055C433F5 for ; Thu, 25 Nov 2021 13:57:43 +0000 (UTC) Received: from localhost ([::1]:40016 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mqFFv-0000ek-2t for qemu-devel@archiver.kernel.org; Thu, 25 Nov 2021 08:57:43 -0500 Received: from eggs.gnu.org ([209.51.188.92]:46104) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mqFBs-00031U-L3 for qemu-devel@nongnu.org; Thu, 25 Nov 2021 08:53:34 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:29773) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mqFBr-0000OI-2g for qemu-devel@nongnu.org; Thu, 25 Nov 2021 08:53:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637848410; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DW6mnFoKl4Tr6p5LoW3lzBoW8GmYZ/8HM6fQnbgibzE=; b=f67n5snU4TeAwuScwwkoS8j8g05dc/HUn9/bEsLz51zwoSk8CpQr42J5z2b3ZOFiM01p6A X/pmcn+xekR9tS1z8QcuLbF0snxVCPohdEFGOFSrksP2JpsqOwl0CECMIjk+YI5Q42cfJ2 ZnlfEJD3850lS0z8hpnMt83iMpdA30M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-175-QstCObGKNbOXc7obWK1DLg-1; Thu, 25 Nov 2021 08:53:27 -0500 X-MC-Unique: QstCObGKNbOXc7obWK1DLg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6CA8810144E1; Thu, 25 Nov 2021 13:53:26 +0000 (UTC) Received: from localhost (unknown [10.39.193.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 39EBC5D6B1; Thu, 25 Nov 2021 13:53:23 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH 1/2] block-backend: Retain permissions after migration Date: Thu, 25 Nov 2021 14:53:16 +0100 Message-Id: <20211125135317.186576-2-hreitz@redhat.com> In-Reply-To: <20211125135317.186576-1-hreitz@redhat.com> References: <20211125135317.186576-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peng Liang , Hanna Reitz , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" After migration, the permissions the guest device wants to impose on its BlockBackend are stored in blk->perm and blk->shared_perm. In blk_root_activate(), we take our permissions, but keep all shared permissions open by calling `blk_set_perm(blk->perm, BLK_PERM_ALL)`. Only afterwards (immediately or later, depending on the runstate) do we restrict the shared permissions by calling `blk_set_perm(blk->perm, blk->shared_perm)`. Unfortunately, our first call with shared_perm=BLK_PERM_ALL has overwritten blk->shared_perm to be BLK_PERM_ALL, so this is a no-op and the set of shared permissions is not restricted. Fix this bug by saving the set of shared permissions before invoking blk_set_perm() with BLK_PERM_ALL and restoring it afterwards. Fixes: 5f7772c4d0cf32f4e779fcd5a69ae4dae24aeebf ("block-backend: Defer shared_perm tightening migration completion") Reported-by: Peng Liang Signed-off-by: Hanna Reitz Reviewed-by: Philippe Mathieu-Daudé Tested-by: Peng Liang --- block/block-backend.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/block/block-backend.c b/block/block-backend.c index 12ef80ea17..41e388fe1f 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -190,6 +190,7 @@ static void blk_root_activate(BdrvChild *child, Error **errp) { BlockBackend *blk = child->opaque; Error *local_err = NULL; + uint64_t saved_shared_perm; if (!blk->disable_perm) { return; @@ -197,12 +198,22 @@ static void blk_root_activate(BdrvChild *child, Error **errp) blk->disable_perm = false; + /* + * blk->shared_perm contains the permissions we want to share once + * migration is really completely done. For now, we need to share + * all; but we also need to retain blk->shared_perm, which is + * overwritten by a successful blk_set_perm() call. Save it and + * restore it below. + */ + saved_shared_perm = blk->shared_perm; + blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err); if (local_err) { error_propagate(errp, local_err); blk->disable_perm = true; return; } + blk->shared_perm = saved_shared_perm; if (runstate_check(RUN_STATE_INMIGRATE)) { /* Activation can happen when migration process is still active, for