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 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 83339C432BE for ; Fri, 27 Aug 2021 04:52:20 +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 46A626056C for ; Fri, 27 Aug 2021 04:52:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 46A626056C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:58044 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJTql-0002Xu-GM for qemu-devel@archiver.kernel.org; Fri, 27 Aug 2021 00:52:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60590) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJTpO-0008Ly-Gv for qemu-devel@nongnu.org; Fri, 27 Aug 2021 00:50:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33749) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJTpM-0000u2-JH for qemu-devel@nongnu.org; Fri, 27 Aug 2021 00:50:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1630039852; 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=eGOMPqPIK3zE39aLwpP+1nyk+wkkeD2/xgsLngEUHIE=; b=ZKA07k0+fQwLGVa0qaCJPhlQf++E9U3N738mQ0hS+hBxwXK1d9RbVPbruke8eaDbtVo5Iw mnk9oWctpU0nv8mvlzyIn8t6PRb4Pct3ufb07QEY5l4/9rIiSsy54vQ+6a90vdx2N9mugN 1NLM1QYcjZoRxdnOXe+RVSNFEDYe/sg= 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-259-lsY_b76uPFmk48IoyvKhpQ-1; Fri, 27 Aug 2021 00:50:50 -0400 X-MC-Unique: lsY_b76uPFmk48IoyvKhpQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 31E06871803; Fri, 27 Aug 2021 04:50:49 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-4.ams2.redhat.com [10.36.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 254CF5D9C6; Fri, 27 Aug 2021 04:50:45 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 867F811380B0; Fri, 27 Aug 2021 06:50:44 +0200 (CEST) From: Markus Armbruster To: qemu-devel@nongnu.org Subject: [PULL 03/15] spapr: Explain purpose of ->fwnmi_migration_blocker more clearly Date: Fri, 27 Aug 2021 06:50:32 +0200 Message-Id: <20210827045044.388748-4-armbru@redhat.com> In-Reply-To: <20210827045044.388748-1-armbru@redhat.com> References: <20210827045044.388748-1-armbru@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.742, 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_H2=-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 , peter.maydell@linaro.org, "Michael S . Tsirkin" , "Dr . David Alan Gilbert" , Ganesh Goudar , 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 Message-Id: <20210720125408.387910-4-armbru@redhat.com> Acked-by: Michael S. Tsirkin --- 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 690533cbdc..630e86282c 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