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 C6FEAC00454 for ; Tue, 10 Dec 2019 11:34:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D89120726 for ; Tue, 10 Dec 2019 11:34:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="B6QAkM6F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727518AbfLJLen (ORCPT ); Tue, 10 Dec 2019 06:34:43 -0500 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:62301 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727320AbfLJLen (ORCPT ); Tue, 10 Dec 2019 06:34:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1575977682; x=1607513682; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=IKPqIf9U+emKxRr0L9uELmQeeXO75kuyRnRZTLa/FT0=; b=B6QAkM6FGHQK+n6JqFEeRTZju5qA/KxiwVuWojs9ZS6EgCdlj8os6X3q 3oWZe06vFo5KVf3KW9blCVq08eNXxpm6N5l5iF4xpgNVDFOmk5lRz6xgf OsNpom3Oydt9AAgyYyI/sOiHZ8DnCGMs1hxTlTbOpPYWg8bhFYeCClb8O k=; IronPort-SDR: pAKF5MoAr76J9iO89BZo3uc8b1Jq1EE0fQSdRsliBQFEAmOwujQiv6pHuhrAy/NjYWjuvaYCSe xQd6Q8GGdWnQ== X-IronPort-AV: E=Sophos;i="5.69,299,1571702400"; d="scan'208";a="12635074" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2a-90c42d1d.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 10 Dec 2019 11:34:42 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2a-90c42d1d.us-west-2.amazon.com (Postfix) with ESMTPS id 26633A192C; Tue, 10 Dec 2019 11:34:41 +0000 (UTC) Received: from EX13D32EUC001.ant.amazon.com (10.43.164.159) by EX13MTAUEA001.ant.amazon.com (10.43.61.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Tue, 10 Dec 2019 11:34:13 +0000 Received: from EX13MTAUEE001.ant.amazon.com (10.43.62.200) by EX13D32EUC001.ant.amazon.com (10.43.164.159) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Tue, 10 Dec 2019 11:34:12 +0000 Received: from u2f063a87eabd5f.cbg10.amazon.com (10.125.106.135) by mail-relay.amazon.com (10.43.62.226) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Tue, 10 Dec 2019 11:34:11 +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 v2 4/4] xen-blkback: support dynamic unbind/bind Date: Tue, 10 Dec 2019 11:33:47 +0000 Message-ID: <20191210113347.3404-5-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191210113347.3404-1-pdurrant@amazon.com> References: <20191210113347.3404-1-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 fio --name=randwrite --ioengine=libaio --iodepth=16 \ --rw=randwrite --bs=4k --direct=1 --size=1G --verify=crc32; 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 v2: - Apply a sanity check to the value of rsp_prod and fail the re-attach if it is implausible - Set allow_rebind to prevent ring from being closed on unbind - Update test workload from dd to fio (with verification) --- drivers/block/xen-blkback/xenbus.c | 59 +++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 18 deletions(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index e8c5c54e1d26..13d09630b237 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -181,6 +181,8 @@ static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref, { int err; struct xen_blkif *blkif = ring->blkif; + struct blkif_common_sring *sring_common; + RING_IDX rsp_prod, req_prod; /* Already connected through? */ if (ring->irq) @@ -191,46 +193,66 @@ static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref, if (err < 0) return err; + sring_common = (struct blkif_common_sring *)ring->blk_ring; + rsp_prod = READ_ONCE(sring_common->rsp_prod); + req_prod = READ_ONCE(sring_common->req_prod); + switch (blkif->blk_protocol) { case BLKIF_PROTOCOL_NATIVE: { - struct blkif_sring *sring; - sring = (struct blkif_sring *)ring->blk_ring; - BACK_RING_INIT(&ring->blk_rings.native, sring, - XEN_PAGE_SIZE * nr_grefs); + struct blkif_sring *sring_native = + (struct blkif_sring *)ring->blk_ring; + unsigned int size = __RING_SIZE(sring_native, + XEN_PAGE_SIZE * nr_grefs); + + BACK_RING_ATTACH(&ring->blk_rings.native, sring_native, + rsp_prod, XEN_PAGE_SIZE * nr_grefs); + err = (req_prod - rsp_prod > size) ? -EIO : 0; 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); + struct blkif_x86_32_sring *sring_x86_32 = + (struct blkif_x86_32_sring *)ring->blk_ring; + unsigned int size = __RING_SIZE(sring_x86_32, + XEN_PAGE_SIZE * nr_grefs); + + BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32, + rsp_prod, XEN_PAGE_SIZE * nr_grefs); + err = (req_prod - rsp_prod > size) ? -EIO : 0; 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); + struct blkif_x86_64_sring *sring_x86_64 = + (struct blkif_x86_64_sring *)ring->blk_ring; + unsigned int size = __RING_SIZE(sring_x86_64, + XEN_PAGE_SIZE * nr_grefs); + + BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64, + rsp_prod, XEN_PAGE_SIZE * nr_grefs); + err = (req_prod - rsp_prod > size) ? -EIO : 0; break; } default: BUG(); } + if (err < 0) + goto fail; err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, xen_blkif_be_int, 0, "blkif-backend", ring); - if (err < 0) { - xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring); - ring->blk_rings.common.sring = NULL; - return err; - } + if (err < 0) + goto fail; ring->irq = err; return 0; + +fail: + xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring); + ring->blk_rings.common.sring = NULL; + return err; } static int xen_blkif_disconnect(struct xen_blkif *blkif) @@ -1121,7 +1143,8 @@ static struct xenbus_driver xen_blkbk_driver = { .ids = xen_blkbk_ids, .probe = xen_blkbk_probe, .remove = xen_blkbk_remove, - .otherend_changed = frontend_changed + .otherend_changed = frontend_changed, + .allow_rebind = true, }; int xen_blkif_xenbus_init(void) -- 2.20.1