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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 6B886C07E9B for ; Tue, 20 Jul 2021 12:58:10 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 0961C61165 for ; Tue, 20 Jul 2021 12:58:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0961C61165 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56000 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m5pK5-0004m3-41 for qemu-devel@archiver.kernel.org; Tue, 20 Jul 2021 08:58:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50820) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m5pGM-0004ey-QU for qemu-devel@nongnu.org; Tue, 20 Jul 2021 08:54:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:48972) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m5pGK-0008Gq-1J for qemu-devel@nongnu.org; Tue, 20 Jul 2021 08:54:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626785655; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GZ1q2MYPGu49QOTbjqzdIl9/u+FXvgLsoW4DA3BJq4Q=; b=ikmsuJIGoc0/+Erfh6gWdmICk4nV2hzj6grqf2JzWXfhx3iICCid0q46Tr9aOlA+dynXaL bk7n//C7Xg+JCVVJk/w4M8AamM9p0yDop00VetANqi/JHbyQNvHq5eDyGWnQFT6qayh34/ qs20a7bJuM9W/IrJZ7xiHarQydxQaJI= 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-199-gOCnyc92PWS94GMmpZk0gA-1; Tue, 20 Jul 2021 08:54:12 -0400 X-MC-Unique: gOCnyc92PWS94GMmpZk0gA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B970A81C85E; Tue, 20 Jul 2021 12:54:10 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-114-187.ams2.redhat.com [10.36.114.187]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 858845C1CF; Tue, 20 Jul 2021 12:54:10 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id EFC4D112D844; Tue, 20 Jul 2021 14:54:08 +0200 (CEST) From: Markus Armbruster To: qemu-devel@nongnu.org Subject: [PATCH 03/16] spapr: Explain purpose of ->fwnmi_migration_blocker more clearly Date: Tue, 20 Jul 2021 14:53:55 +0200 Message-Id: <20210720125408.387910-4-armbru@redhat.com> In-Reply-To: <20210720125408.387910-1-armbru@redhat.com> References: <20210720125408.387910-1-armbru@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.474, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Aravinda Prasad , Ganesh Goudar , "Dr . David Alan Gilbert" , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" spapr_mce_req_event() makes an effort to prevent migration from degrading the reporting of FWNMIs. It adds a migration blocker when it receives one, and deletes it when it's done handling it. This is a best effort. Commit 2500fb423a "migration: Include migration support for machine check handling" tried to explain this in a comment. Rewrite the comment for clarity, and reposition it to make it clear it applies to all failure modes, not just "migration already in progress". Cc: David Gibson Cc: Aravinda Prasad Cc: Ganesh Goudar Cc: Dr. David Alan Gilbert Signed-off-by: Markus Armbruster --- hw/ppc/spapr_events.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c index a8f2cc6bdc..7d6876f12d 100644 --- a/hw/ppc/spapr_events.c +++ b/hw/ppc/spapr_events.c @@ -911,16 +911,17 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered) } } + /* + * Try to block migration while FWNMI is being handled, so the + * machine check handler runs where the information passed to it + * actually makes sense. This shouldn't actually block migration, + * only delay it slightly, assuming migration is retried. If the + * attempt to block fails, carry on. Unfortunately, it always + * fails when running with -only-migrate. A proper interface to + * delay migration completion for a bit could avoid that. + */ ret = migrate_add_blocker(spapr->fwnmi_migration_blocker, NULL); if (ret == -EBUSY) { - /* - * We don't want to abort so we let the migration to continue. - * In a rare case, the machine check handler will run on the target. - * Though this is not preferable, it is better than aborting - * the migration or killing the VM. It is okay to call - * migrate_del_blocker on a blocker that was not added (which the - * nmi-interlock handler would do when it's called after this). - */ warn_report("Received a fwnmi while migration was in progress"); } -- 2.31.1