From patchwork Wed Dec 11 15:29:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 11285385 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 D8DD6188B for ; Wed, 11 Dec 2019 15:31:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B820A22B48 for ; Wed, 11 Dec 2019 15:31:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="ZAt7m5R4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387480AbfLKPbC (ORCPT ); Wed, 11 Dec 2019 10:31:02 -0500 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:40792 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387473AbfLKPa7 (ORCPT ); Wed, 11 Dec 2019 10:30:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1576078259; x=1607614259; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=N22hyGYPk1JoqY1Qt0Vz9EReiYVT9fCIbFq3JobjLc4=; b=ZAt7m5R4wlVOi42u6PT6RReA/pxDSMQGBSBOYV/Cth66ihR6T1xGnkdi 8qYYT4Xch5ZHL6UX8PPyLf+0JHdaJHM8KQNnnqwjrzmlGey3l7Do00p3+ WWYJ2foddSBgVMqGg49e4yF2tU1sMl8fp4j0Pn/i5+iDhGjphMlIzhZ8t Y=; IronPort-SDR: J9/38YbMpalD44EqUzMsZ76zibWP7tf+mT+iXkGgPFEVIRtKljVza3qOgqGg0rbr/3/l0JZmLp 5vb/yvqk5YQQ== X-IronPort-AV: E=Sophos;i="5.69,301,1571702400"; d="scan'208";a="12930184" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2b-81e76b79.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 11 Dec 2019 15:30:47 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2b-81e76b79.us-west-2.amazon.com (Postfix) with ESMTPS id 7A6AFA2173; Wed, 11 Dec 2019 15:30:46 +0000 (UTC) Received: from EX13D32EUB002.ant.amazon.com (10.43.166.114) by EX13MTAUEA001.ant.amazon.com (10.43.61.243) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 11 Dec 2019 15:30:14 +0000 Received: from EX13MTAUWC001.ant.amazon.com (10.43.162.135) by EX13D32EUB002.ant.amazon.com (10.43.166.114) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 11 Dec 2019 15:30:13 +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; Wed, 11 Dec 2019 15:30:10 +0000 From: Paul Durrant To: , , CC: Paul Durrant , Konrad Rzeszutek Wilk , =?utf-8?q?Roger_Pau_Monn?= =?utf-8?q?=C3=A9?= , Jens Axboe , Boris Ostrovsky , Juergen Gross , "Stefano Stabellini" Subject: [PATCH v3 4/4] xen-blkback: support dynamic unbind/bind Date: Wed, 11 Dec 2019 15:29:56 +0000 Message-ID: <20191211152956.5168-5-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191211152956.5168-1-pdurrant@amazon.com> References: <20191211152956.5168-1-pdurrant@amazon.com> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@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 Reviewed-by: Juergen Gross Reviewed-by: Roger Pau Monné --- Cc: Konrad Rzeszutek Wilk Cc: "Roger Pau Monné" Cc: Jens Axboe Cc: Boris Ostrovsky Cc: Juergen Gross Cc: Stefano Stabellini v3: - Constify sring_common and re-work error handling in xen_blkif_map() 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 | 56 ++++++++++++++++++++---------- 1 file changed, 38 insertions(+), 18 deletions(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 59d576d27ca7..0d4097bdff3f 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -190,6 +190,9 @@ static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref, { int err; struct xen_blkif *blkif = ring->blkif; + const struct blkif_common_sring *sring_common; + RING_IDX rsp_prod, req_prod; + unsigned int size; /* Already connected through? */ if (ring->irq) @@ -200,46 +203,62 @@ 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; + + BACK_RING_ATTACH(&ring->blk_rings.native, sring_native, + rsp_prod, XEN_PAGE_SIZE * nr_grefs); + size = __RING_SIZE(sring_native, 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); + struct blkif_x86_32_sring *sring_x86_32 = + (struct blkif_x86_32_sring *)ring->blk_ring; + + BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32, + rsp_prod, XEN_PAGE_SIZE * nr_grefs); + size = __RING_SIZE(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); + struct blkif_x86_64_sring *sring_x86_64 = + (struct blkif_x86_64_sring *)ring->blk_ring; + + BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64, + rsp_prod, XEN_PAGE_SIZE * nr_grefs); + size = __RING_SIZE(sring_x86_64, XEN_PAGE_SIZE * nr_grefs); break; } default: BUG(); } + err = -EIO; + if (req_prod - rsp_prod > size) + 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) @@ -1131,7 +1150,8 @@ 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)