From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E9E0AC43603 for ; Thu, 5 Dec 2019 14:02:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B23E22464D for ; Thu, 5 Dec 2019 14:02:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="RVgbpOdg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729654AbfLEOCB (ORCPT ); Thu, 5 Dec 2019 09:02:01 -0500 Received: from smtp-fw-6002.amazon.com ([52.95.49.90]:22558 "EHLO smtp-fw-6002.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729598AbfLEOCA (ORCPT ); Thu, 5 Dec 2019 09:02:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1575554519; x=1607090519; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=1WJZpOjGUIHVRhgcjBz3yJxjB5haQQg6kXg1z4d6ets=; b=RVgbpOdgiK+xSOiR47dMVbre1KMRaE2eEKkTFpLw1YeGKnqHpq2ccnmG 4RUJvkwiv6mB5cKWf+VFQiGZRYTleuH0w2s55RIBZbnxtyQclCl0rFbAD X6nj8G9gKjxrKmoAdxYNlgy4Mn9dx6VWm3x/8W8Fo7ecsYugILbM94qin E=; IronPort-SDR: loNKSiQNwG75LMDfydCOTefyzN9ieNk12e8ueIaZsuDiGfR+2DLVXIwfiA2ChyEQXKkm9x/Dym IWYCNYTcFGTg== X-IronPort-AV: E=Sophos;i="5.69,281,1571702400"; d="scan'208";a="6345518" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-1d-2c665b5d.us-east-1.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-6002.iad6.amazon.com with ESMTP; 05 Dec 2019 14:01:58 +0000 Received: from EX13MTAUEA001.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan3.iad.amazon.com [10.40.159.166]) by email-inbound-relay-1d-2c665b5d.us-east-1.amazon.com (Postfix) with ESMTPS id 04AB0A2A13; Thu, 5 Dec 2019 14:01:55 +0000 (UTC) Received: from EX13D32EUC001.ant.amazon.com (10.43.164.159) by EX13MTAUEA001.ant.amazon.com (10.43.61.243) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 5 Dec 2019 14:01:46 +0000 Received: from EX13MTAUWC001.ant.amazon.com (10.43.162.135) by EX13D32EUC001.ant.amazon.com (10.43.164.159) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 5 Dec 2019 14:01:43 +0000 Received: from u2f063a87eabd5f.cbg10.amazon.com (10.125.106.135) by mail-relay.amazon.com (10.43.162.232) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Thu, 5 Dec 2019 14:01:40 +0000 From: Paul Durrant To: , CC: Paul Durrant , Konrad Rzeszutek Wilk , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Jens Axboe , Boris Ostrovsky , Juergen Gross , "Stefano Stabellini" Subject: [PATCH 4/4] xen-blkback: support dynamic unbind/bind Date: Thu, 5 Dec 2019 14:01:23 +0000 Message-ID: <20191205140123.3817-5-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191205140123.3817-1-pdurrant@amazon.com> References: <20191205140123.3817-1-pdurrant@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org By simply re-attaching to shared rings during connect_ring() rather than assuming they are freshly allocated (i.e assuming the counters are zero) it is possible for vbd instances to be unbound and re-bound from and to (respectively) a running guest. This has been tested by running: while true; do dd if=/dev/urandom of=test.img bs=1M count=1024; done in a PV guest whilst running: while true; do echo vbd-$DOMID-$VBD >unbind; echo unbound; sleep 5; echo vbd-$DOMID-$VBD >bind; echo bound; sleep 3; done in dom0 from /sys/bus/xen-backend/drivers/vbd to continuously unbind and re-bind its system disk image. This is a highly useful feature for a backend module as it allows it to be unloaded and re-loaded (i.e. updated) without requiring domUs to be halted. This was also tested by running: while true; do echo vbd-$DOMID-$VBD >unbind; echo unbound; sleep 5; rmmod xen-blkback; echo unloaded; sleep 1; modprobe xen-blkback; echo bound; cd $(pwd); sleep 3; done in dom0 whilst running the same loop as above in the (single) PV guest. Some (less stressful) testing has also been done using a Windows HVM guest with the latest 9.0 PV drivers installed. Signed-off-by: Paul Durrant --- Cc: Konrad Rzeszutek Wilk Cc: "Roger Pau Monné" Cc: Jens Axboe Cc: Boris Ostrovsky Cc: Juergen Gross Cc: Stefano Stabellini --- drivers/block/xen-blkback/xenbus.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index e8c5c54e1d26..0b82740c4a9d 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -196,24 +196,24 @@ static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref, { struct blkif_sring *sring; sring = (struct blkif_sring *)ring->blk_ring; - BACK_RING_INIT(&ring->blk_rings.native, sring, - XEN_PAGE_SIZE * nr_grefs); + BACK_RING_ATTACH(&ring->blk_rings.native, sring, + XEN_PAGE_SIZE * nr_grefs); break; } case BLKIF_PROTOCOL_X86_32: { struct blkif_x86_32_sring *sring_x86_32; sring_x86_32 = (struct blkif_x86_32_sring *)ring->blk_ring; - BACK_RING_INIT(&ring->blk_rings.x86_32, sring_x86_32, - XEN_PAGE_SIZE * nr_grefs); + BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32, + XEN_PAGE_SIZE * nr_grefs); break; } case BLKIF_PROTOCOL_X86_64: { struct blkif_x86_64_sring *sring_x86_64; sring_x86_64 = (struct blkif_x86_64_sring *)ring->blk_ring; - BACK_RING_INIT(&ring->blk_rings.x86_64, sring_x86_64, - XEN_PAGE_SIZE * nr_grefs); + BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64, + XEN_PAGE_SIZE * nr_grefs); break; } default: -- 2.20.1