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=-9.8 required=3.0 tests=BAYES_00,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, URIBL_BLOCKED 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 682B4C433E7 for ; Mon, 12 Oct 2020 12:57:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AF3E2076E for ; Mon, 12 Oct 2020 12:57:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QYU4g9SS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728858AbgJLM5e (ORCPT ); Mon, 12 Oct 2020 08:57:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:27575 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbgJLM5e (ORCPT ); Mon, 12 Oct 2020 08:57:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602507452; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GC8VOJiDkG6ErANTb/WlUuIOAAehbykdKgaBnzsSpVw=; b=QYU4g9SSHdbM86vXZ9hm1UWh8Qs46eN6zk1sR58L32N4Y/HSRmCyGxrOs456OhwBokp6s2 3jg4d8dBPHgZ3YR0zzpGp1EqSk4T4dC4/U/gjMOMd/CsZlGndGk4bW7Ggi1deFlcUxg6j0 i7kfgcA9XT1Ma2kezHywSIHtN6wX2/A= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-34-pUaSbvp5NBOvnPhuhjfrhg-1; Mon, 12 Oct 2020 08:57:30 -0400 X-MC-Unique: pUaSbvp5NBOvnPhuhjfrhg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E74851074658; Mon, 12 Oct 2020 12:57:28 +0000 (UTC) Received: from t480s.redhat.com (ovpn-113-251.ams2.redhat.com [10.36.113.251]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5621160C07; Mon, 12 Oct 2020 12:57:19 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, virtualization@lists.linux-foundation.org, Andrew Morton , "Michael S . Tsirkin" , David Hildenbrand , Jason Wang , Pankaj Gupta , Michal Hocko , Oscar Salvador , Wei Yang Subject: [PATCH v1 28/29] virtio-mem: Big Block Mode (BBM) - basic memory hotunplug Date: Mon, 12 Oct 2020 14:53:22 +0200 Message-Id: <20201012125323.17509-29-david@redhat.com> In-Reply-To: <20201012125323.17509-1-david@redhat.com> References: <20201012125323.17509-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Let's try to unplug completely offline big blocks first. Then, (if enabled via unplug_offline) try to offline and remove whole big blocks. No locking necessary - we can deal with concurrent onlining/offlining just fine. Note1: This is sub-optimal and might be dangerous in some environments: we could end up in an infinite loop when offlining (e.g., long-term pinnings), similar as with DIMMs. We'll introduce safe memory hotunplug via fake-offlining next, and use this basic mode only when explicitly enabled. Note2: Without ZONE_MOVABLE, memory unplug will be extremely unreliable with bigger block sizes. Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: Pankaj Gupta Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Cc: Andrew Morton Signed-off-by: David Hildenbrand --- drivers/virtio/virtio_mem.c | 156 +++++++++++++++++++++++++++++++++++- 1 file changed, 155 insertions(+), 1 deletion(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 94cf44b15cbf..6bcd0acbff32 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -388,6 +388,12 @@ static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm) _bb_id++) \ if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state) +#define virtio_mem_bbm_for_each_bb_rev(_vm, _bb_id, _state) \ + for (_bb_id = vm->bbm.next_bb_id - 1; \ + _bb_id >= vm->bbm.first_bb_id && _vm->bbm.bb_count[_state]; \ + _bb_id--) \ + if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state) + /* * Set the state of a memory block, taking care of the state counter. */ @@ -685,6 +691,18 @@ static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id) return virtio_mem_remove_memory(vm, addr, size); } +/* + * See virtio_mem_remove_memory(): Try to remove all Linux memory blocks covered + * by the big block. + */ +static int virtio_mem_bbm_remove_bb(struct virtio_mem *vm, unsigned long bb_id) +{ + const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id); + const uint64_t size = vm->bbm.bb_size; + + return virtio_mem_remove_memory(vm, addr, size); +} + /* * Try offlining and removing memory from Linux. * @@ -731,6 +749,19 @@ static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm, return virtio_mem_offline_and_remove_memory(vm, addr, size); } +/* + * See virtio_mem_offline_and_remove_memory(): Try to offline and remove a + * all Linux memory blocks covered by the big block. + */ +static int virtio_mem_bbm_offline_and_remove_bb(struct virtio_mem *vm, + unsigned long bb_id) +{ + const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id); + const uint64_t size = vm->bbm.bb_size; + + return virtio_mem_offline_and_remove_memory(vm, addr, size); +} + /* * Trigger the workqueue so the device can perform its magic. */ @@ -1928,6 +1959,129 @@ static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff) return rc; } +/* + * Try to offline and remove a big block from Linux and unplug it. Will fail + * with -EBUSY if some memory is busy and cannot get unplugged. + * + * Will modify the state of the memory block. Might temporarily drop the + * hotplug_mutex. + */ +static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm, + unsigned long bb_id) +{ + int rc; + + if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) != + VIRTIO_MEM_BBM_BB_ADDED)) + return -EINVAL; + + rc = virtio_mem_bbm_offline_and_remove_bb(vm, bb_id); + if (rc) + return rc; + + rc = virtio_mem_bbm_unplug_bb(vm, bb_id); + if (rc) + virtio_mem_bbm_set_bb_state(vm, bb_id, + VIRTIO_MEM_BBM_BB_PLUGGED); + else + virtio_mem_bbm_set_bb_state(vm, bb_id, + VIRTIO_MEM_BBM_BB_UNUSED); + return rc; +} + +/* + * Try to remove a big block from Linux and unplug it. Will fail with + * -EBUSY if some memory is online. + * + * Will modify the state of the memory block. + */ +static int virtio_mem_bbm_remove_and_unplug_bb(struct virtio_mem *vm, + unsigned long bb_id) +{ + int rc; + + if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) != + VIRTIO_MEM_BBM_BB_ADDED)) + return -EINVAL; + + rc = virtio_mem_bbm_remove_bb(vm, bb_id); + if (rc) + return -EBUSY; + + rc = virtio_mem_bbm_unplug_bb(vm, bb_id); + if (rc) + virtio_mem_bbm_set_bb_state(vm, bb_id, + VIRTIO_MEM_BBM_BB_PLUGGED); + else + virtio_mem_bbm_set_bb_state(vm, bb_id, + VIRTIO_MEM_BBM_BB_UNUSED); + return rc; +} + +/* + * Test if a big block is completely offline. + */ +static bool virtio_mem_bbm_bb_is_offline(struct virtio_mem *vm, + unsigned long bb_id) +{ + const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id)); + const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size); + unsigned long pfn; + + for (pfn = start_pfn; pfn < start_pfn + nr_pages; + pfn += PAGES_PER_SECTION) { + if (pfn_to_online_page(pfn)) + return false; + } + + return true; +} + +static int virtio_mem_bbm_unplug_request(struct virtio_mem *vm, uint64_t diff) +{ + uint64_t nb_bb = diff / vm->bbm.bb_size; + uint64_t bb_id; + int rc; + + if (!nb_bb) + return 0; + + /* Try to unplug completely offline big blocks first. */ + virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) { + cond_resched(); + /* + * As we're holding no locks, this check is racy as memory + * can get onlined in the meantime - but we'll fail gracefully. + */ + if (!virtio_mem_bbm_bb_is_offline(vm, bb_id)) + continue; + rc = virtio_mem_bbm_remove_and_unplug_bb(vm, bb_id); + if (rc == -EBUSY) + continue; + if (!rc) + nb_bb--; + if (rc || !nb_bb) + return rc; + } + + if (!unplug_online) + return 0; + + /* Try to unplug any big blocks. */ + virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) { + cond_resched(); + rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id); + if (rc == -EBUSY) + continue; + if (!rc) + nb_bb--; + if (rc || !nb_bb) + return rc; + } + + return nb_bb ? -EBUSY : 0; +} + /* * Try to unplug the requested amount of memory. */ @@ -1935,7 +2089,7 @@ static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff) { if (vm->in_sbm) return virtio_mem_sbm_unplug_request(vm, diff); - return -EBUSY; + return virtio_mem_bbm_unplug_request(vm, diff); } /* -- 2.26.2