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 54B7DC35FF3 for ; Fri, 21 Mar 2025 06:47:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tvWAJ-0005xH-7f; Fri, 21 Mar 2025 02:47:35 -0400 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 1tvWAH-0005wl-7M for qemu-devel@nongnu.org; Fri, 21 Mar 2025 02:47:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tvWAF-00067j-HO for qemu-devel@nongnu.org; Fri, 21 Mar 2025 02:47:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1742539649; 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=UX93a6LydHJg68wZ+2Yiv6aOAz3lPbFCuSwXV8rehu8=; b=NYNwzQTWXA/KfTwblzzNFDKEXO3zNwpN43Y38ObbbEK7RmfGngK5pKplodHc2Y5JlLfkOy Y5HKy+Rf5+l+j/1ggZljkYPWnpO6HawBey2/ZxdlGAKRTa5UI9Zc0exvDMtIuPW5o6QFb7 IGSEQMSo6ZwFNqyOF1N7bLo999hdJaU= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-392--Nrn-csCMoOFyYqbnfqAKA-1; Fri, 21 Mar 2025 02:47:25 -0400 X-MC-Unique: -Nrn-csCMoOFyYqbnfqAKA-1 X-Mimecast-MFC-AGG-ID: -Nrn-csCMoOFyYqbnfqAKA_1742539644 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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 mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2FB311944F0A; Fri, 21 Mar 2025 06:47:23 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.22.74.4]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C38021828A93; Fri, 21 Mar 2025 06:47:21 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 0BD3721E66C4; Fri, 21 Mar 2025 07:47:18 +0100 (CET) From: Markus Armbruster To: Bibo Mao Cc: Song Gao , Jiaxun Yang , qemu-devel@nongnu.org, Paolo Bonzini Subject: Re: [PATCH v6 3/6] hw/loongarch/virt: Fix error handling in cpu unplug In-Reply-To: <20250321031259.2419842-4-maobibo@loongson.cn> (Bibo Mao's message of "Fri, 21 Mar 2025 11:12:56 +0800") References: <20250321031259.2419842-1-maobibo@loongson.cn> <20250321031259.2419842-4-maobibo@loongson.cn> Date: Fri, 21 Mar 2025 07:47:18 +0100 Message-ID: <87ecyq98y1.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 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.332, 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_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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 Bibo Mao writes: > In function virt_cpu_unplug(), it will send cpu unplug message to > interrupt controller extioi and ipi irqchip. If there is problem in > this function, system should continue to run and keep state the same > before cpu is removed. > > If error happends in cpu unplug stage, send cpu plug message to extioi > and ipi irqchip to restore to previous stage, and then return immediately. > > Fixes: 2cd6857f6f5b (hw/loongarch/virt: Implement cpu unplug interface) > Signed-off-by: Bibo Mao > --- > hw/loongarch/virt.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c > index 8563967c8b..503362a69e 100644 > --- a/hw/loongarch/virt.c > +++ b/hw/loongarch/virt.c > @@ -958,6 +958,8 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, > hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->extioi), dev, &err); > if (err) { > error_propagate(errp, err); > + hotplug_handler_plug(HOTPLUG_HANDLER(lvms->ipi), dev, > + &error_abort); > return; > } > > @@ -965,6 +967,10 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, > hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err); > if (err) { > error_propagate(errp, err); > + hotplug_handler_plug(HOTPLUG_HANDLER(lvms->ipi), dev, > + &error_abort); > + hotplug_handler_plug(HOTPLUG_HANDLER(lvms->extioi), dev, > + &error_abort); > return; > } virt_cpu_unplug() calls hotplug_handler_unplug() three times to notify ipi, extioi, and acpi_get. If any notification fails, virt_cpu_unplug() calls hotplug_handler_plug() to "un-notify" the preceeding ones, if any. This must not fail. virt_cpu_plug() does it the other way round (see previous patch). So, hotplug_handler_plug() must not fail in virt_cpu_unplug(), yet we check for it to fail in virt_cpu_plug(). Can it really fail in virt_cpu_plug()? If yes, why can't it fail in virt_cpu_unplug()? Same questions for hotplug_handler_unplug().