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 674BCC6FD1D for ; Tue, 4 Apr 2023 12:47:11 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pjg3R-0007gV-R1; Tue, 04 Apr 2023 08:46:29 -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 1pjg3M-0007g2-LF for qemu-devel@nongnu.org; Tue, 04 Apr 2023 08:46:24 -0400 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 1pjg3K-0003op-Uq for qemu-devel@nongnu.org; Tue, 04 Apr 2023 08:46:24 -0400 Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-449-GJtXN90dNYGsBaL8kKQMiQ-1; Tue, 04 Apr 2023 08:46:20 -0400 X-MC-Unique: GJtXN90dNYGsBaL8kKQMiQ-1 Received: by mail-ed1-f69.google.com with SMTP id t14-20020a056402240e00b004fb36e6d670so45645135eda.5 for ; Tue, 04 Apr 2023 05:46:20 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680612379; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=u/hL4MX8D7qF3+aqq/oVih+V1m8I1WqtawQN76J6xoo=; b=Ul1mzCnm8gfhfqgEjrQTjDGJ40y/vSisPf1QJ82K50L3BVrcCpiSKlZ+mHuyq9hOu+ Zc59s2YyyIoe5+uozQFsz5qsfH9wzGJRWaq8R7bkk4rDK+e3NJciUY/VWnfF7QBhYRMM sB9lRKGVhHZtJdhDZNzNzq75sm+IgoMVm8c6Z/2AOyADcx5U8T2ya4ZRtSVtuWL2zjFA xRgMv/maR2HknakLGSjsUp4lKHVy4k98HXCcewhXVJf1xMkKJxPfOCKaNuQbGvnaBIol vEQvMSQXG8g5gr5OOXhOLIJs5bda0vwwJNd9FpyQgbdKaBBoG7jKqenmK9/t9Bc2X7Pl 2Wfw== X-Gm-Message-State: AAQBX9fPn/eMeMimVSWiQesGzpxjktaI7Orzr1jfVRggrhcJq7dt//96 fwbhlMy8W9CfdVnYTiUc37E0+Izr1zTxWDSNQBtdXnXUBekZUh42NDkhBsIuxe5GBVL6G8fIwhQ zfy8DQQw5axwPMG8= X-Received: by 2002:a05:6402:26d5:b0:4af:7bdc:188e with SMTP id x21-20020a05640226d500b004af7bdc188emr21363634edd.16.1680612379376; Tue, 04 Apr 2023 05:46:19 -0700 (PDT) X-Google-Smtp-Source: AKy350aeFdvedHQCteOO29W5en8qgO9CSNrO66MvO+w9fHNsRWLLvTUCz85AxFuxSJ6KjhLmF0KTxA== X-Received: by 2002:a05:6402:26d5:b0:4af:7bdc:188e with SMTP id x21-20020a05640226d500b004af7bdc188emr21363623edd.16.1680612379108; Tue, 04 Apr 2023 05:46:19 -0700 (PDT) Received: from redhat.com ([2.52.129.179]) by smtp.gmail.com with ESMTPSA id cy8-20020a0564021c8800b00502689a06b2sm5760718edb.91.2023.04.04.05.46.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Apr 2023 05:46:18 -0700 (PDT) Date: Tue, 4 Apr 2023 08:46:15 -0400 From: "Michael S. Tsirkin" To: Igor Mammedov Cc: qemu-devel@nongnu.org, anisinha@redhat.com, jusual@redhat.com, kraxel@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH] acpi: pcihp: make pending delete expire in 5sec Message-ID: <20230404084603-mutt-send-email-mst@kernel.org> References: <20230403161618.1344414-1-imammedo@redhat.com> <20230403131833-mutt-send-email-mst@kernel.org> <20230404102807.4626b0be@imammedo.users.ipa.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230404102807.4626b0be@imammedo.users.ipa.redhat.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 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 On Tue, Apr 04, 2023 at 10:28:07AM +0200, Igor Mammedov wrote: > On Mon, 3 Apr 2023 13:23:45 -0400 > "Michael S. Tsirkin" wrote: > > > On Mon, Apr 03, 2023 at 06:16:18PM +0200, Igor Mammedov wrote: > > > with Q35 using ACPI PCI hotplug by default, user's request to unplug > > > device is ignored when it's issued before guest OS has been booted. > > > And any additional attempt to request device hot-unplug afterwards > > > results in following error: > > > > > > "Device XYZ is already in the process of unplug" > > > > > > arguably it can be considered as a regression introduced by [2], > > > before which it was possible to issue unplug request multiple > > > times. > > > > > > Allowing pending delete expire brings ACPI PCI hotplug on par > > > with native PCIe unplug behavior [1] which in its turn refers > > > back to ACPI PCI hotplug ability to repeat unplug requests. > > > > > > PS: > > > >From ACPI point of view, unplug request sets PCI hotplug status > > > bit in GPE0 block. However depending on OSPM, status bits may > > > be retained (Windows) or cleared (Linux) during guest's ACPI > > > subsystem initialization, and as result Linux guest looses > > > plug/unplug event (no SCI generated) if plug/unplug has > > > happend before guest OS initialized GPE registers handling. > > > I couldn't find any restrictions wrt OPM clearing GPE status > > > bits ACPI spec. > > > Hence a fallback approach is to let user repeat unplug request > > > later at the time when guest OS has booted. > > > > > > 1) 18416c62e3 ("pcie: expire pending delete") > > > 2) > > > Fixes: cce8944cc9ef ("qdev-monitor: Forbid repeated device_del") > > > Signed-off-by: Igor Mammedov > > > > A bit concerned about how this interacts with failover, > > and 5sec is a lot of time that I hoped we'd avoid with acpi. > > Any better ideas of catching such misbehaving guests? > > It shouldn't affect affect failover, pending_delete is not > cleared after all (only device removal should do that). > So all patch does is allowing to reissue unplug request > in case it was lost, delay here doesn't mean much > (do you have any preference wrt specific value)? I'd prefer immediately. > As for 'misbehaving' - I tried to find justification > for it in spec, but I couldn't. > Essentially it's upto OSPM to clear or not GPE status > bits at startup (linux was doing it since forever), > depending on guest's ability to handle hotplug events > at boot time. > > It's more a user error, ACPI hotplug does imply booted > guest for it to function properly. So it's fine to > loose unplug event at boot time. What QEMU does wrong is > preventing follow up unplug requests. > > > > > Also at this point I do not know why we deny hotplug > > pending_deleted_event in qdev core. > > Commit log says: > > > > Device unplug can be done asynchronously. Thus, sending the second > > device_del before the previous unplug is complete may lead to > > unexpected results. On PCIe devices, this cancels the hot-unplug > > process. > > > > so it's a work around for an issue in pcie hotplug (and maybe shpc > > too?). Maybe we should have put that check in pcie/shpc and > > leave acpi along? > > > > > > > > > > > --- > > > CC: mst@redhat.com > > > CC: anisinha@redhat.com > > > CC: jusual@redhat.com > > > CC: kraxel@redhat.com > > > --- > > > hw/acpi/pcihp.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c > > > index dcfb779a7a..cd4f9fee0a 100644 > > > --- a/hw/acpi/pcihp.c > > > +++ b/hw/acpi/pcihp.c > > > @@ -357,6 +357,8 @@ void acpi_pcihp_device_unplug_request_cb(HotplugHandler *hotplug_dev, > > > * acpi_pcihp_eject_slot() when the operation is completed. > > > */ > > > pdev->qdev.pending_deleted_event = true; > > > + pdev->qdev.pending_deleted_expires_ms = > > > + qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 5000; /* 5 secs */ > > > s->acpi_pcihp_pci_status[bsel].down |= (1U << slot); > > > acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS); > > > } > > > -- > > > 2.39.1 > >