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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6C13DC35274 for ; Mon, 18 Dec 2023 14:03:26 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rFECg-0000sr-HN; Mon, 18 Dec 2023 09:02:42 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rFECd-0000s7-5a for qemu-devel@nongnu.org; Mon, 18 Dec 2023 09:02:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rFECa-0003i8-Qs for qemu-devel@nongnu.org; Mon, 18 Dec 2023 09:02:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702908154; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=I9DK5YSlv9uF1Lmdx4qMkQ/lfRNdyPwYcrpXMB/3ClY=; b=RoWuPQ8qIEPjMBCCeBgu3q94Du7yhYJOrR1JUh4C1LWxy1Mj3hHARgQ19jLqkHcfiTfVv3 Nto6BpgCBAfLWPwOiomu4NwTxMnuk5SG/MsUc0LotF53J5ARSSm9K12wGfifAdUOUvksLP zByYJC9cxLf3Dt6DRMuwJjpOoT0crSk= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-531-jKpEcjakPtSvy0g6hBVZpw-1; Mon, 18 Dec 2023 09:02:33 -0500 X-MC-Unique: jKpEcjakPtSvy0g6hBVZpw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0EC8D3833369; Mon, 18 Dec 2023 14:02:13 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.129]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DF83A492BC6; Mon, 18 Dec 2023 14:02:12 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id BF19C21E6920; Mon, 18 Dec 2023 15:02:11 +0100 (CET) From: Markus Armbruster To: Akihiko Odaki Cc: Paolo Bonzini , Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9?= , Eduardo Habkost , qemu-devel@nongnu.org Subject: Re: [PATCH v2] qdev: Report an error for machine without HotplugHandler In-Reply-To: (Akihiko Odaki's message of "Wed, 13 Dec 2023 18:50:47 +0900") References: <20231210-bus-v2-1-34ebf5726fa0@daynix.com> <87h6kpgrl7.fsf@pond.sub.org> Date: Mon, 18 Dec 2023 15:02:11 +0100 Message-ID: <8734vzsj6k.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.083, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Akihiko Odaki writes: > On 2023/12/11 15:51, Markus Armbruster wrote: >> Akihiko Odaki writes: >> >>> The HotplugHandler of the machine will be used when the parent bus does >>> not exist, but the machine may not have one. Report an error in such a >>> case instead of aborting. >>> >>> Fixes: 7716b8ca74 ("qdev: HotplugHandler: Add support for unplugging BUS-less devices") >>> Signed-off-by: Akihiko Odaki >> >> Do you have a reproducer for the crash? >> >>> --- >>> Changes in v2: >>> - Fixed indention. >>> - Link to v1: https://lore.kernel.org/r/20231202-bus-v1-1-f7540e3a8d62@daynix.com >>> --- >>> system/qdev-monitor.c | 13 ++++++++++--- >>> 1 file changed, 10 insertions(+), 3 deletions(-) >>> >>> diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c >>> index a13db763e5..5fe5d49c20 100644 >>> --- a/system/qdev-monitor.c >>> +++ b/system/qdev-monitor.c >>> @@ -927,9 +927,16 @@ void qdev_unplug(DeviceState *dev, Error **errp) >> void qdev_unplug(DeviceState *dev, Error **errp) >> { >> DeviceClass *dc = DEVICE_GET_CLASS(dev); >> HotplugHandler *hotplug_ctrl; >> HotplugHandlerClass *hdc; >> Error *local_err = NULL; >> if (qdev_unplug_blocked(dev, errp)) { >> return; >> } >> if (dev->parent_bus && !qbus_is_hotpluggable(dev->parent_bus)) { >> error_setg(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name); >> return; >> } >> if (!dc->hotpluggable) { >> error_setg(errp, QERR_DEVICE_NO_HOTPLUG, >> object_get_typename(OBJECT(dev))); >> return; >> } >> if (!migration_is_idle() && !dev->allow_unplug_during_migration) { >> error_setg(errp, "device_del not allowed while migrating"); >> return; >> } >> >>> qdev_hot_removed = true; >>> hotplug_ctrl = qdev_get_hotplug_handler(dev); >>> - /* hotpluggable device MUST have HotplugHandler, if it doesn't >>> - * then something is very wrong with it */ >>> - g_assert(hotplug_ctrl); >>> + if (!hotplug_ctrl) { >>> + /* >>> + * hotpluggable bus MUST have HotplugHandler, if it doesn't >>> + * then something is very wrong with it >>> + */ >>> + assert(!dev->parent_bus); >>> + >>> + error_setg(errp, "The machine does not support hotplugging for a device without parent bus"); >>> + return; >>> + } >> >> Extended version of my question above: what are the devices where >> qdev_get_hotplug_handler(dev) returns null here? > > Start a VM: qemu-system-aarch64 -M virt -nographic > Run the following on its HMP: device_del /machine/unattached/device[0] > > It tries to unplug cortex-a15-arm-cpu and crashes. This device has no parent bus (dev->parent_bus is null), but is marked hot-pluggable (dc->hotpluggable is true). Question for somebody familiar with the hot-plug machinery: is this sane?