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=-13.5 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 84413C4361B for ; Thu, 10 Dec 2020 18:43:17 +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 C831C221E8 for ; Thu, 10 Dec 2020 18:43:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C831C221E8 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]:44484 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1knQuJ-0006yA-PS for qemu-devel@archiver.kernel.org; Thu, 10 Dec 2020 13:43:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41430) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1knQrI-0005dX-Tb for qemu-devel@nongnu.org; Thu, 10 Dec 2020 13:40:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:33903) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1knQrC-0003dG-9z for qemu-devel@nongnu.org; Thu, 10 Dec 2020 13:40:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607625600; 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=UyUf2z94P2VdxWHOSrvh5OP2sMM8+a+b2gFBtx5ni24=; b=iV7dDLU9Q1DldNu8ZimLlcndVHzVE759sLM+m/sLdbdd/HMPUlzO23yauhj1WV4LK+mimq CM+ox7fn4JraLzE0lg7U6DHZmbF6CWKZ7+mjztl96CQ92HbCgkTf0cgCusRG1M6mEZeQbt dO1QSbKs02AQJZjewSlNKjKDgDmBkpQ= 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-294-geo25HAcMRqT69Ew2LGsZw-1; Thu, 10 Dec 2020 13:39:58 -0500 X-MC-Unique: geo25HAcMRqT69Ew2LGsZw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ABC53184214B; Thu, 10 Dec 2020 18:39:56 +0000 (UTC) Received: from gondolin (ovpn-112-67.ams2.redhat.com [10.36.112.67]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5D5FA1F443; Thu, 10 Dec 2020 18:39:41 +0000 (UTC) Date: Thu, 10 Dec 2020 19:39:39 +0100 From: Cornelia Huck To: Shenming Lu Subject: Re: [RFC PATCH v2 2/3] vfio: Set the priority of the VFIO VM state change handler explicitly Message-ID: <20201210193939.5c29997b.cohuck@redhat.com> In-Reply-To: <817ace0f-ddcf-db7f-8f92-f94cc450fb90@huawei.com> References: <20201209080919.156-1-lushenming@huawei.com> <20201209080919.156-3-lushenming@huawei.com> <20201209134537.5c7ab401.cohuck@redhat.com> <817ace0f-ddcf-db7f-8f92-f94cc450fb90@huawei.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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 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: Lorenzo Pieralisi , Neo Jia , mst@redhat.com, qemu-devel@nongnu.org, Marc Zyngier , Kirti Wankhede , "Dr . David Alan Gilbert" , Eric Auger , Alex Williamson , qemu-arm@nongnu.org, yuzenghui@huawei.com, wanghaibin.wang@huawei.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 10 Dec 2020 11:11:17 +0800 Shenming Lu wrote: > On 2020/12/9 20:45, Cornelia Huck wrote: > > On Wed, 9 Dec 2020 16:09:18 +0800 > > Shenming Lu wrote: > > > >> In the VFIO VM state change handler, VFIO devices are transitioned > >> in the _SAVING state, which should keep them from sending interrupts. > >> Then we can save the pending states of all interrupts in the GIC VM > >> state change handler (on ARM). > >> > >> So we have to set the priority of the VFIO VM state change handler > >> explicitly (like virtio devices) to ensure it is called before the > >> GIC's in saving. > > > > What this patch does is to make the priority of the vfio migration > > state change handler depending on the position in the qdev tree. As all > > state change handlers with no explicit priority are added at priority > > 0, this will make sure that this handler runs before (save) resp. after > > (restore) nearly all other handlers, which will address your issue here > > (and possibly similar ones). > > > > So, this patch seems fine for now, but I'm wondering whether we need to > > think more about priorities for handlers in general, and if there are > > more hidden dependencies lurking in there. > > As far as I know, as for the migration of interrupt, on x86 the sync from > the PIR field to the Virtual-APIC page for posted interrupts (in > KVM_GET_LAPIC ioctl) is after the pause of VFIO devices, which is fine. > Not sure about others... Interrupt handling had been my first guess, but it seems most interrupt controllers don't use a state change handler anyway. "handlers in general" actually also referred to use cases outside of vfio migration, so out of scope of this patch... > > Thanks, > Shenming > > > > >> > >> Signed-off-by: Shenming Lu > >> Reviewed-by: Kirti Wankhede > >> --- > >> hw/vfio/migration.c | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c > >> index 3b9de1353a..97ea82b100 100644 > >> --- a/hw/vfio/migration.c > >> +++ b/hw/vfio/migration.c > >> @@ -862,7 +862,8 @@ static int vfio_migration_init(VFIODevice *vbasedev, > >> register_savevm_live(id, VMSTATE_INSTANCE_ID_ANY, 1, &savevm_vfio_handlers, > >> vbasedev); > >> > >> - migration->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change, > >> + migration->vm_state = qdev_add_vm_change_state_handler(vbasedev->dev, > >> + vfio_vmstate_change, > >> vbasedev); > >> migration->migration_state.notify = vfio_migration_state_notifier; > >> add_migration_state_change_notifier(&migration->migration_state); > > > > . > > > In any case, Reviewed-by: Cornelia Huck