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 EF31BC6FD1D for ; Tue, 4 Apr 2023 14:40:36 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pjhpj-00036W-Dc; Tue, 04 Apr 2023 10:40:27 -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 1pjhph-00034P-En for qemu-devel@nongnu.org; Tue, 04 Apr 2023 10:40:25 -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 1pjhpf-0007Vt-E8 for qemu-devel@nongnu.org; Tue, 04 Apr 2023 10:40:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680619222; 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=wUUHHSUP/YRbicKm8dUXGbDQ0wHKd7XBQivwQT70oQQ=; b=S5sYrZK5edBd8Ee+mmnBq/3uRoYjaOTpZiaAN/qsQ12NDkRI9Uk8+3NGY9+lhdAnPjBwwx s/WVeDxTlVpjCF3LIHCHjrVb8MUzyUjjIgvD35+4mKHe3+sM0+Si6m8G1AAp6LrvqKq7z7 8E+hRYuWSeBrPfFpaPKcEOefY0Z6aBk= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-399-gN9WT0sFMEWPtqjn0TXB9w-1; Tue, 04 Apr 2023 10:40:21 -0400 X-MC-Unique: gN9WT0sFMEWPtqjn0TXB9w-1 Received: by mail-ed1-f70.google.com with SMTP id v1-20020a50d581000000b0050291cda08aso12874349edi.15 for ; Tue, 04 Apr 2023 07:40:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680619220; h=in-reply-to:content-transfer-encoding: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=wUUHHSUP/YRbicKm8dUXGbDQ0wHKd7XBQivwQT70oQQ=; b=tSxUwmA7hfIQ1LY9+8kx5xbXZxYxYl3IaWlSyTWQePGGfWgeAOV7y17Vy+uWQggvy0 MH4/x/539WZm19rrp9U5PWO4ntVCBt8WI2mdJxk1k3+v6wKZpiMbLXRc0oZhfPjOGzcZ eO14AS2tRu7xb6z+jDT6RH4CVtEWeu6bxRapZcneoMpzx7uO8cecVEiEUPpMWYjoULrV +2hj6F9ZslYhseWr4yyQ7pZORwI4RviM50YlopTXOW3kAKiqr8x9LXrgqHeXmA9930wX h02O7bbiMO7aZp/PDRQEfBU1j0wA4fzmN98GN82SOJ8E4TZlbAw9G9jBD6EI9ZCfMmcf TOdw== X-Gm-Message-State: AAQBX9f/Ncdd0VnUgl2v/Xi8bYgLiQUxITHi09UlWtxEsMpdxYmOxtSg UJC59gKl8WGIlbe0Eoy3f15Jl0iNvTOJYUboDvOo0frS00eJ2emmOSPdJQKcO75TX3eibZMejyg 0a7deax5qNcTgtPA= X-Received: by 2002:a17:906:5659:b0:931:99b5:6791 with SMTP id v25-20020a170906565900b0093199b56791mr2035324ejr.72.1680619220355; Tue, 04 Apr 2023 07:40:20 -0700 (PDT) X-Google-Smtp-Source: AKy350Y2bgWG98rrLi4v5CRxpPJF5eWnfvztcWGHKHesDHkvA0BZLLxGVkDs+q9F0GUXjl+BKDOg5A== X-Received: by 2002:a17:906:5659:b0:931:99b5:6791 with SMTP id v25-20020a170906565900b0093199b56791mr2035313ejr.72.1680619220078; Tue, 04 Apr 2023 07:40:20 -0700 (PDT) Received: from redhat.com ([2.52.129.179]) by smtp.gmail.com with ESMTPSA id be6-20020a1709070a4600b00949173c1dcfsm892479ejc.18.2023.04.04.07.40.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Apr 2023 07:40:19 -0700 (PDT) Date: Tue, 4 Apr 2023 10:40:16 -0400 From: "Michael S. Tsirkin" To: Ani Sinha Cc: Igor Mammedov , qemu-devel@nongnu.org, jusual@redhat.com, kraxel@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH] acpi: pcihp: make pending delete expire in 5sec Message-ID: <20230404103953-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> <20230404084603-mutt-send-email-mst@kernel.org> <20230404160435.45c2513d@imammedo.users.ipa.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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: -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_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 07:40:40PM +0530, Ani Sinha wrote: > > > On Tue, Apr 4, 2023 at 7:34 PM Igor Mammedov wrote: > > On Tue, 4 Apr 2023 08:46:15 -0400 > "Michael S. Tsirkin" wrote: > > > 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. > > ok, lets use 1ms then, I'd rather reuse the preexisting > pending_deleted_expires_ms machinery instead of > special-casing immediate repeat. > > > Sounds good to me. >   OK but please add a comment explaining what's going on. > > > > > > 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    > > > >    > > > >