From patchwork Mon Dec 23 09:59:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 11307969 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6749614F6 for ; Mon, 23 Dec 2019 10:01:11 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 380332053B for ; Mon, 23 Dec 2019 10:01:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="VzL6NakN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 380332053B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ijKV3-00052b-CB; Mon, 23 Dec 2019 09:59:41 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ijKV2-00052W-II for xen-devel@lists.xenproject.org; Mon, 23 Dec 2019 09:59:40 +0000 X-Inumbo-ID: ee7d6153-256a-11ea-96b9-12813bfff9fa Received: from smtp-fw-33001.amazon.com (unknown [207.171.190.10]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id ee7d6153-256a-11ea-96b9-12813bfff9fa; Mon, 23 Dec 2019 09:59:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1577095180; x=1608631180; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=AXLA4oTaOxQEJPJrsHXELfBXcoU1aXhP5KDiSUct76c=; b=VzL6NakNmD7eUUuwec2teTcTV3pzRvnG4sYu9d5XcxZaRi9ohDDveBMp 4HHovW5EyjTmzWbDzns/2rhCv49qR6uW+Ubian6jzgYpzwf2cMqSPIp2W ODhDzsfyOWCtK9QDJb2dtBqiBEsXKcVfDFN4CiSNJKqZ5w558Dj+luVb3 g=; IronPort-SDR: rLgT1+3QwmMpnM5bGo0ssD6aR/h2FMREnjuVxYeVCxnfm9Ui3zS68hR6AN9C/j+TMaPe1k5tmu bj8hhWJJy1zw== X-IronPort-AV: E=Sophos;i="5.69,347,1571702400"; d="scan'208";a="16521924" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-1e-a70de69e.us-east-1.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-33001.sea14.amazon.com with ESMTP; 23 Dec 2019 09:59:29 +0000 Received: from EX13MTAUEA002.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan2.iad.amazon.com [10.40.159.162]) by email-inbound-relay-1e-a70de69e.us-east-1.amazon.com (Postfix) with ESMTPS id 769FAA119C; Mon, 23 Dec 2019 09:59:27 +0000 (UTC) Received: from EX13D32EUB002.ant.amazon.com (10.43.166.114) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1236.3; Mon, 23 Dec 2019 09:59:27 +0000 Received: from EX13MTAUEA001.ant.amazon.com (10.43.61.82) by EX13D32EUB002.ant.amazon.com (10.43.166.114) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 23 Dec 2019 09:59:26 +0000 Received: from u2f063a87eabd5f.cbg10.amazon.com (10.125.106.135) by mail-relay.amazon.com (10.43.61.243) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Mon, 23 Dec 2019 09:59:24 +0000 From: Paul Durrant To: , , Date: Mon, 23 Dec 2019 09:59:23 +0000 Message-ID: <20191223095923.2458-1-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [PATCH net-next] xen-netback: support dynamic unbind/bind X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Paul Durrant , "David S. Miller" , Wei Liu , Paul Durrant Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" By re-attaching RX, TX, and CTL rings during connect() rather than assuming they are freshly allocated (i.e. assuming the counters are zero), and avoiding forcing state to Closed in netback_remove() it is possible for vif instances to be unbound and re-bound from and to (respectively) a running guest. Dynamic unbind/bind 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 has been tested by running iperf as a server in the test VM and then running a client against it in a continuous loop, whilst also running: while true; do echo vif-$DOMID-$VIF >unbind; echo down; rmmod xen-netback; echo unloaded; modprobe xen-netback; cd $(pwd); brctl addif xenbr0 vif$DOMID.$VIF; ip link set vif$DOMID.$VIF up; echo up; sleep 5; done in dom0 from /sys/bus/xen-backend/drivers/vif to continuously unbind, unload, re-load, re-bind and re-plumb the backend. Clearly a performance drop was seen but no TCP connection resets were observed during this test and moreover a parallel SSH connection into the guest remained perfectly usable throughout. Signed-off-by: Paul Durrant Reviewed-by: Wei Liu --- Cc: Wei Liu Cc: Paul Durrant Cc: "David S. Miller" --- drivers/net/xen-netback/interface.c | 10 +++++++++- drivers/net/xen-netback/netback.c | 20 +++++++++++++++++--- drivers/net/xen-netback/xenbus.c | 5 ++--- 3 files changed, 28 insertions(+), 7 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index f15ba3de6195..0c8a02a1ead7 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -585,6 +585,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref, struct net_device *dev = vif->dev; void *addr; struct xen_netif_ctrl_sring *shared; + RING_IDX rsp_prod, req_prod; int err; err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif), @@ -593,7 +594,14 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref, goto err; shared = (struct xen_netif_ctrl_sring *)addr; - BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE); + rsp_prod = READ_ONCE(shared->rsp_prod); + req_prod = READ_ONCE(shared->req_prod); + + BACK_RING_ATTACH(&vif->ctrl, shared, rsp_prod, XEN_PAGE_SIZE); + + err = -EIO; + if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl)) + goto err_unmap; err = bind_interdomain_evtchn_to_irq(vif->domid, evtchn); if (err < 0) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 0020b2e8c279..315dfc6ea297 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1453,7 +1453,7 @@ int xenvif_map_frontend_data_rings(struct xenvif_queue *queue, void *addr; struct xen_netif_tx_sring *txs; struct xen_netif_rx_sring *rxs; - + RING_IDX rsp_prod, req_prod; int err = -ENOMEM; err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif), @@ -1462,7 +1462,14 @@ int xenvif_map_frontend_data_rings(struct xenvif_queue *queue, goto err; txs = (struct xen_netif_tx_sring *)addr; - BACK_RING_INIT(&queue->tx, txs, XEN_PAGE_SIZE); + rsp_prod = READ_ONCE(txs->rsp_prod); + req_prod = READ_ONCE(txs->req_prod); + + BACK_RING_ATTACH(&queue->tx, txs, rsp_prod, XEN_PAGE_SIZE); + + err = -EIO; + if (req_prod - rsp_prod > RING_SIZE(&queue->tx)) + goto err; err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif), &rx_ring_ref, 1, &addr); @@ -1470,7 +1477,14 @@ int xenvif_map_frontend_data_rings(struct xenvif_queue *queue, goto err; rxs = (struct xen_netif_rx_sring *)addr; - BACK_RING_INIT(&queue->rx, rxs, XEN_PAGE_SIZE); + rsp_prod = READ_ONCE(rxs->rsp_prod); + req_prod = READ_ONCE(rxs->req_prod); + + BACK_RING_ATTACH(&queue->rx, rxs, rsp_prod, XEN_PAGE_SIZE); + + err = -EIO; + if (req_prod - rsp_prod > RING_SIZE(&queue->rx)) + goto err; return 0; diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index 17b4950ec051..286054b60d47 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -954,12 +954,10 @@ static int netback_remove(struct xenbus_device *dev) { struct backend_info *be = dev_get_drvdata(&dev->dev); - set_backend_state(be, XenbusStateClosed); - unregister_hotplug_status_watch(be); if (be->vif) { kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE); - xen_unregister_watchers(be->vif); + backend_disconnect(be); xenvif_free(be->vif); be->vif = NULL; } @@ -1131,6 +1129,7 @@ static struct xenbus_driver netback_driver = { .remove = netback_remove, .uevent = netback_uevent, .otherend_changed = frontend_changed, + .allow_rebind = true, }; int xenvif_xenbus_init(void)