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 9CCF2C433F5 for ; Tue, 8 Mar 2022 16:31:42 +0000 (UTC) Received: from localhost ([::1]:59860 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nRckP-0003rt-Lp for qemu-devel@archiver.kernel.org; Tue, 08 Mar 2022 11:31:41 -0500 Received: from eggs.gnu.org ([209.51.188.92]:36724) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nRcj6-0002RV-GQ for qemu-devel@nongnu.org; Tue, 08 Mar 2022 11:30:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:54552) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nRcj2-0000eY-Bu for qemu-devel@nongnu.org; Tue, 08 Mar 2022 11:30:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1646757014; 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=lGV1wFL5ji4hHhng4tQzRaaZDyBLyCs929ocrJqqSGI=; b=KLqA8eDmSkoXg5y2pwFlEinUpdN5n9gyEv5jq/NQ1blSMBIkhigIUd77aJmoItZG4wS4Sj AkEYbQWzZQvZ6K/5pzgYy9OHRR4ztaq9PKIlYOOiB3T+izHJXXmhKg671mie8fmvLDlygu j2buS0zxx74X5NsDTcax/++OznrNKpw= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-422-ZFc51le6OZyrSF07oQbxsA-1; Tue, 08 Mar 2022 11:30:13 -0500 X-MC-Unique: ZFc51le6OZyrSF07oQbxsA-1 Received: by mail-wm1-f72.google.com with SMTP id a26-20020a7bc1da000000b003857205ec7cso1318968wmj.2 for ; Tue, 08 Mar 2022 08:30:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=lGV1wFL5ji4hHhng4tQzRaaZDyBLyCs929ocrJqqSGI=; b=0Ud5WZZENqK+AwI8br4vwUqtDn4OcZbEIIlhm3REHjeaWjuKNMTVDzheRLwAFz+Zhl PymRnFepLKt4LHHfFVpJWz8lkW7ARjljBx8MrH9mvyqWI4YDVlJQp2OTfFjUuO+RehpI 9iR1EN2HJNKPRFdBRcA4Uz8fA9lY7O90HX2sV+rilyF2MDV7uTi3vULIFUSbPAqUUfdX fjYoB4L+mrPkuZsR7qALGrJapUm0hRTqA1ZTA0yBs0iWVhc1TOoopbnpSIp9e4zhQ0+A oHup8JirNBwTXv/bpZXm8gjhIoWQe793vOgW7JA5qPf4QQL/eoX+MsPO6GCOu4/ctqA1 /wDg== X-Gm-Message-State: AOAM532Ysr/3KTUQ3ZZGcjMwPFw+O825fsH/IZ2vHqKgkq1oxmC9f6tC vZb9qj/uFGzAkFjPADGpXpVU2gz0L1es4YQEgJdI9esZ86MzOMyEG/SehCXWaNnCB31+R+v/EH4 y4M3ms7v+Py/rjXo= X-Received: by 2002:a05:600c:5011:b0:389:948e:bb4 with SMTP id n17-20020a05600c501100b00389948e0bb4mr4179580wmr.107.1646757011758; Tue, 08 Mar 2022 08:30:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJxNVJMH+GeemumCEzXAIFukv6Ab2Dn9rBemq8p72XtqGjOBY5LpBbB1lf8wxjCUnp9NyDPBbw== X-Received: by 2002:a05:600c:5011:b0:389:948e:bb4 with SMTP id n17-20020a05600c501100b00389948e0bb4mr4179549wmr.107.1646757011338; Tue, 08 Mar 2022 08:30:11 -0800 (PST) Received: from redhat.com ([2.55.24.184]) by smtp.gmail.com with ESMTPSA id p2-20020a1c7402000000b0038159076d30sm2634677wmc.22.2022.03.08.08.30.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Mar 2022 08:30:10 -0800 (PST) Date: Tue, 8 Mar 2022 11:30:07 -0500 From: "Michael S. Tsirkin" To: Ani Sinha Subject: Re: [libvirt] [PATCH RESEND v2 0/4] re-introduce Message-ID: <20220308112811-mutt-send-email-mst@kernel.org> References: <20220308063955.2285902-1-ani@anisinha.ca> <399ca3a9-8b95-39af-8376-85f2edf00c7e@redhat.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Cc: libvir-list@redhat.com, imammedo@redhat.com, jusual@redhat.com, qemu list , Laine Stump Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Mar 08, 2022 at 09:57:04PM +0530, Ani Sinha wrote: > > > On Tue, Mar 8, 2022 at 21:21 Laine Stump wrote: > > Aha! the domain of qemu-devel@nongnu.org was incorrect in the original > send (it was "nognu.org"), so none of this thread was making it to that > list. I've corrected it in this message, but interested parties from > qemu-devel will need to look on the libvir-list archives for the actual > patch mails: > > https://listman.redhat.com/archives/libvir-list/2022-March/229089.html > > Anyone else who responds to any of the mail on this thread should fix > the qemu-devel address accordingly. > > > This patch set has been a true test of my diligence and perseverance 🙂 Right. But could you maybe repost to the proper qemu-devel? I'd like to be able to pull the whole email not just the summary listman deems safe to show me. > > > > On 3/8/22 10:33 AM, Laine Stump wrote: > > On 3/8/22 1:39 AM, Ani Sinha wrote: > >> Changelog: > >> v2 - rebased the patch series to latest master. > >> > >> I am re-introducing the patchset for which got > >> reverted here few months back: > >> > >> https://www.spinics.net/linux/fedora/libvir/msg224089.html > >> > >> The reason for the reversal was that there seemed to be some > >> instability/issues around the use of the qemu commandline which this > >> patchset tries to support. In particular, some guest operating systems > >> did not like the way QEMU was trying to disable native hotplug on pcie > >> root ports. > > > > My memory isn't completely clear, but I think there was also the issue > > that the option claims to enable ACPI hotplug when set to on, but > > instead what it actually does (in the Q35 case at least) is to enable > > native PCI hotplug when set to off (without actually disabling ACPI > > hotplug) and disable native PCI hotplug when set to on, or something > > like that. This ends up leaving it up to the guest OS to decide which > > type of hotplug to use, meaning its decision could override what's in > > the libvirt config, thus confusing everyone. Again, I probably have the > > details mixed up, but it was something like this. > > > > I asked mst about this this morning, and he suggested something that > > you've already done - Cc'ing the series to qemu-devel and the relevant > > maintainers so we can have a discussion with all involved parties about > > their opinions on whether we really should expose this existing option > > in libvirt, or if we should instead have two new options that are more > > orthogonal about enabling/disabling the two types of hotplug, so that > > libvirt config can more accurately represent what is being presented to > > the guest rather than a "best guess" of what we think the guest is going > > to do with what is presented. > > > > (Michael did also say that, with the current flurry of bug reports for > > the QEMU rc's, this discusion may not happen until closer to release > > when the bug reports die down. I know this doesn't mesh with your desire > > to "push now to allow for testing" (which in general would be a good > > thing if we were certain that we wanted the option like this and were > > just expecting some minor bugs that could be fixed), but my opinion is > > that 1) it's possible for anyone interested to test the functionality > > using , and 2) we should avoid turning libvirt git > > into a revolving door of experiments. The only practical difference > > between using and having a dedicated option is that > > the use of causes the domain to be tainted, and the > > XML is a bit more complicated. But since the people we're talking about > > here will already have built their own libvirt binaries, the tainted > > status of any guests is irrelevant and the extra complexity of using > > is probably trivial to them :-). > > > >> Subsequently, in QEMU 6.2, we have changed our mechanism > >> using which we disable native hotplug. As I understand, we do not have > >> any reported issues so far in 6.2 around this area. QEMU will enter a > >> soft feature freeze in the first week of march in prep for 7.0 release. > >> Libvirt is also entering a new release cycle phaze. Hence, I am > >> introducing this patchset early enough in the release cycles so that if > >> we do see any issues on the qemu side during the rc0, rc1 cycles and if > >> reversal of this patchset is again required, it can be done in time > >> before the next libvirt release end of March. > >> > >> All the patches in this series had been previously reviewed. Some > >> subsequent fixes were made after my initial patches were pushed. I have > >> squashed all those fixes and consolidated them into four patches. I have > >> also updated the documentation to reflect the new changes from the QEMU > >> side and rebased my changes fixing the tests in the process. > >> > >> What changed in QEMU post version 6.1 ? > >> ========================================= > >> > >> We have made basically two major changes in QEMU. First is this change: > >> > >> (1) commit 211afe5c69b597acf85fdd577eb497f5be1ffbd8 > >> Author: Julia Suvorova > >> Date:   Fri Nov 12 06:08:56 2021 -0500 > >> > >>      hw/i386/acpi-build: Deny control on PCIe Native Hot-plug in _OSC > >>      There are two ways to enable ACPI PCI Hot-plug: > >>              * Disable the Hot-plug Capable bit on PCIe slots. > >>      This was the first approach which led to regression [1-2], as > >>      I/O space for a port is allocated only when it is hot-pluggable, > >>      which is determined by HPC bit. > >>              * Leave the HPC bit on and disable PCIe Native Hot-plug > >> in _OSC > >>                method. > >>      This removes the (future) ability of hot-plugging switches with > PCIe > >>      Native hotplug since ACPI PCI Hot-plug only works with cold-plugged > >>      bridges. If the user wants to explicitely use this feature, they > can > >>      disable ACPI PCI Hot-plug with: > >>              --global ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off > >>      Change the bit in _OSC method so that the OS selects ACPI PCI > >> Hot-plug > >>      instead of PCIe Native. > >>      [1] https://gitlab.com/qemu-project/qemu/-/issues/641 > >>      [2] https://bugzilla.redhat.com/show_bug.cgi?id=2006409 > >>      Signed-off-by: Julia Suvorova > >>      Signed-off-by: Igor Mammedov > >>      Message-Id: <20211112110857.3116853-5-imammedo@redhat.com> > >>      Reviewed-by: Ani Sinha > >>      Reviewed-by: Michael S. Tsirkin > >>      Signed-off-by: Michael S. Tsirkin > >> > >> > >> The patch description says it all. Instead of masking out the HPC bit in > >> pcie slots, we keep them turned on. Instead, we do not advertize native > >> hotplug capability for PCIE using _OSC control method. See section > >> 6.2.11 in ACPI spec 6.2. At the same time, we turn on ACPI hotplug for > >> these slots so now the guest OS can select ACPI hotplug instead. > >> > >> The second change is introduction of a property with which we keep the > >> existing behavior for pc-q35-6.1 machines. This means HPC bit is masked > >> and ACPI hotplug is enabled by default for pcie root ports. > >> The QEMU commit is: > >> > >> (2) commit c318bef76206c2ecb6016e8e68c4ac6ff9a4c8cb > >> Author: Julia Suvorova > >> Date:   Fri Nov 12 06:08:54 2021 -0500 > >> > >>      hw/acpi/ich9: Add compat prop to keep HPC bit set for 6.1 machine > >> type > >>      To solve issues [1-2] the Hot Plug Capable bit in PCIe Slots will > be > >>      turned on, while the switch to ACPI Hot-plug will be done in the > >>      DSDT table. > >>      Introducing 'x-keep-native-hpc' property disables the HPC bit only > >>      in 6.1 and as a result keeps the forced 'reserve-io' on > >>      pcie-root-ports in 6.1 too. > >>      [1] https://gitlab.com/qemu-project/qemu/-/issues/641 > >>      [2] https://bugzilla.redhat.com/show_bug.cgi?id=2006409 > >>      Signed-off-by: Julia Suvorova > >>      Signed-off-by: Igor Mammedov > >>      Message-Id: <20211112110857.3116853-3-imammedo@redhat.com> > >>      Reviewed-by: Michael S. Tsirkin > >>      Signed-off-by: Michael S. Tsirkin > >> > >> Lastly, as a related side note, because from QEMU 6.2 onwards, we do not > >> mask out HPC bit in PCIE, the work done by this patch is no longer > >> needed: > >> > >> (3) commit e2a6290aab578b2170c1f5909fa556385dc0d820 > >> Author: Marcel Apfelbaum > >> Date:   Mon Aug 2 12:00:57 2021 +0300 > >> > >>      hw/pcie-root-port: Fix hotplug for PCI devices requiring IO > >>      Q35 has now ACPI hotplug enabled by default for PCI(e) devices. > >>      As opposed to native PCIe hotplug, guests like Fedora 34 > >>      will not assign IO range to pcie-root-ports not supporting > >>      native hotplug, resulting into a regression. > >>      Reproduce by: > >>          qemu-bin -M q35 -device pcie-root-port,id=p1 -monitor stdio > >>          device_add e1000,bus=p1 > >>      In the Guest OS the respective pcie-root-port will have the IO > range > >>      disabled. > >>      Fix it by setting the "reserve-io" hint capability of the > >>      pcie-root-ports so the firmware will allocate the IO range instead. > >>      Acked-by: Igor Mammedov > >>      Signed-off-by: Marcel Apfelbaum > >>      Message-Id: <20210802090057.1709775-1-marcel@redhat.com> > >>      Reviewed-by: Michael S. Tsirkin > >>      Signed-off-by: Michael S. Tsirkin > >> > >> This is what commit (2) alludes to. In pc-q35-6.1 machines we do need > >> patch (3) since we mask out HPC bit from pcie ports. > >> > >> > >> I know this is convoluted mess. In fairness I am trying all I can in my > >> spare time to help from the QEMU side. I am determined to see this > >> patchset through into libvirt. > >> > >> Thanks > >> > >> > >> Ani Sinha (4): > >>    qemu: capablities: detect acpi-pci-hotplug-with-bridge-support > >>    conf: introduce support for acpi-bridge-hotplug feature > >>    qemu: command: add support for acpi-bridge-hotplug feature > >>    NEWS: document new acpi pci hotplug config option > >> > >>   NEWS.rst                                      |  8 ++ > >>   docs/formatdomain.rst                         | 32 +++++++ > >>   docs/schemas/domaincommon.rng                 | 15 ++++ > >>   src/conf/domain_conf.c                        | 89 ++++++++++++++++++- > >>   src/conf/domain_conf.h                        |  9 ++ > >>   src/qemu/qemu_capabilities.c                  |  4 + > >>   src/qemu/qemu_capabilities.h                  |  3 + > >>   src/qemu/qemu_command.c                       | 19 ++++ > >>   src/qemu/qemu_validate.c                      | 42 +++++++++ > >>   .../caps_6.1.0.x86_64.xml                     |  1 + > >>   .../caps_6.2.0.x86_64.xml                     |  1 + > >>   .../caps_7.0.0.x86_64.xml                     |  1 + > >>   ...-hotplug-bridge-disable.aarch64-latest.err |  1 + > >>   .../aarch64-acpi-hotplug-bridge-disable.xml   | 13 +++ > >>   ...-hotplug-bridge-disable.x86_64-latest.args | 35 ++++++++ > >>   .../pc-i440fx-acpi-hotplug-bridge-disable.xml | 36 ++++++++ > >>   .../pc-i440fx-acpi-hotplug-bridge-enable.xml  | 36 ++++++++ > >>   ...pi-hotplug-bridge-disable.x86_64-6.0.0.err |  1 + > >>   ...-hotplug-bridge-disable.x86_64-latest.args | 38 ++++++++ > >>   .../q35-acpi-hotplug-bridge-disable.xml       | 53 +++++++++++ > >>   .../q35-acpi-hotplug-bridge-enable.xml        | 53 +++++++++++ > >>   tests/qemuxml2argvtest.c                      |  7 ++ > >>   ...i-hotplug-bridge-disable.x86_64-latest.xml |  1 + > >>   ...pi-hotplug-bridge-enable.x86_64-latest.xml |  1 + > >>   ...i-hotplug-bridge-disable.x86_64-latest.xml |  1 + > >>   ...pi-hotplug-bridge-enable.x86_64-latest.xml |  1 + > >>   tests/qemuxml2xmltest.c                       |  4 + > >>   27 files changed, 504 insertions(+), 1 deletion(-) > >>   create mode 100644 > >> tests/qemuxml2argvdata/ > aarch64-acpi-hotplug-bridge-disable.aarch64-latest.err > >> > >>   create mode 100644 > >> tests/qemuxml2argvdata/aarch64-acpi-hotplug-bridge-disable.xml > >>   create mode 100644 > >> tests/qemuxml2argvdata/ > pc-i440fx-acpi-hotplug-bridge-disable.x86_64-latest.args > >> > >>   create mode 100644 > >> tests/qemuxml2argvdata/pc-i440fx-acpi-hotplug-bridge-disable.xml > >>   create mode 100644 > >> tests/qemuxml2argvdata/pc-i440fx-acpi-hotplug-bridge-enable.xml > >>   create mode 100644 > >> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-disable.x86_64-6.0.0.err > >>   create mode 100644 > >> tests/qemuxml2argvdata/ > q35-acpi-hotplug-bridge-disable.x86_64-latest.args > >>   create mode 100644 > >> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-disable.xml > >>   create mode 100644 > >> tests/qemuxml2argvdata/q35-acpi-hotplug-bridge-enable.xml > >>   create mode 120000 > >> tests/qemuxml2xmloutdata/ > pc-i440fx-acpi-hotplug-bridge-disable.x86_64-latest.xml > >> > >>   create mode 120000 > >> tests/qemuxml2xmloutdata/ > pc-i440fx-acpi-hotplug-bridge-enable.x86_64-latest.xml > >> > >>   create mode 120000 > >> tests/qemuxml2xmloutdata/ > q35-acpi-hotplug-bridge-disable.x86_64-latest.xml > >> > >>   create mode 120000 > >> tests/qemuxml2xmloutdata/ > q35-acpi-hotplug-bridge-enable.x86_64-latest.xml > >> > > > >