<div dir="auto"> </div><div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Mar 8, 2022 at 21:21 Laine Stump <<a href="mailto:laine@redhat.com">laine@redhat.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">Aha! the domain of <a href="mailto:qemu-devel@nongnu.org" target="_blank">qemu-devel@nongnu.org</a> was incorrect in the original send (it was "<a href="http://nognu.org" rel="noreferrer" target="_blank">nognu.org</a>"), 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: <a href="https://listman.redhat.com/archives/libvir-list/2022-March/229089.html" rel="noreferrer" target="_blank">https://listman.redhat.com/archives/libvir-list/2022-March/229089.html</a> Anyone else who responds to any of the mail on this thread should fix the qemu-devel address accordingly.</blockquote><div dir="auto"> </div><div dir="auto">This patch set has been a true test of my diligence and perseverance 🙂</div><div dir="auto"> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)" dir="auto"> 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 <acpi-hotplug-bridge> which got >> reverted here few months back: >> >> <a href="https://www.spinics.net/linux/fedora/libvir/msg224089.html" rel="noreferrer" target="_blank">https://www.spinics.net/linux/fedora/libvir/msg224089.html</a> >> >> 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 <qemu:commandline>, and 2) we should avoid turning libvirt git > into a revolving door of experiments. The only practical difference > between using <qemu:commandline> and having a dedicated option is that > the use of <qemu:commandline> 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 > <qemu:commandline> 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 <<a href="mailto:jusual@redhat.com" target="_blank">jusual@redhat.com</a>> >> 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] <a href="https://gitlab.com/qemu-project/qemu/-/issues/641" rel="noreferrer" target="_blank">https://gitlab.com/qemu-project/qemu/-/issues/641</a> >> [2] <a href="https://bugzilla.redhat.com/show_bug.cgi?id=2006409" rel="noreferrer" target="_blank">https://bugzilla.redhat.com/show_bug.cgi?id=2006409</a> >> Signed-off-by: Julia Suvorova <<a href="mailto:jusual@redhat.com" target="_blank">jusual@redhat.com</a>> >> Signed-off-by: Igor Mammedov <<a href="mailto:imammedo@redhat.com" target="_blank">imammedo@redhat.com</a>> >> Message-Id: <<a href="mailto:20211112110857.3116853-5-imammedo@redhat.com" target="_blank">20211112110857.3116853-5-imammedo@redhat.com</a>> >> Reviewed-by: Ani Sinha <<a href="mailto:ani@anisinha.ca" target="_blank">ani@anisinha.ca</a>> >> Reviewed-by: Michael S. Tsirkin <<a href="mailto:mst@redhat.com" target="_blank">mst@redhat.com</a>> >> Signed-off-by: Michael S. Tsirkin <<a href="mailto:mst@redhat.com" target="_blank">mst@redhat.com</a>> >> >> >> 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 <<a href="mailto:jusual@redhat.com" target="_blank">jusual@redhat.com</a>> >> 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] <a href="https://gitlab.com/qemu-project/qemu/-/issues/641" rel="noreferrer" target="_blank">https://gitlab.com/qemu-project/qemu/-/issues/641</a> >> [2] <a href="https://bugzilla.redhat.com/show_bug.cgi?id=2006409" rel="noreferrer" target="_blank">https://bugzilla.redhat.com/show_bug.cgi?id=2006409</a> >> Signed-off-by: Julia Suvorova <<a href="mailto:jusual@redhat.com" target="_blank">jusual@redhat.com</a>> >> Signed-off-by: Igor Mammedov <<a href="mailto:imammedo@redhat.com" target="_blank">imammedo@redhat.com</a>> >> Message-Id: <<a href="mailto:20211112110857.3116853-3-imammedo@redhat.com" target="_blank">20211112110857.3116853-3-imammedo@redhat.com</a>> >> Reviewed-by: Michael S. Tsirkin <<a href="mailto:mst@redhat.com" target="_blank">mst@redhat.com</a>> >> Signed-off-by: Michael S. Tsirkin <<a href="mailto:mst@redhat.com" target="_blank">mst@redhat.com</a>> >> >> 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 <<a href="mailto:marcel.apfelbaum@gmail.com" target="_blank">marcel.apfelbaum@gmail.com</a>> >> 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 <<a href="mailto:imammedo@redhat.com" target="_blank">imammedo@redhat.com</a>> >> Signed-off-by: Marcel Apfelbaum <<a href="mailto:marcel@redhat.com" target="_blank">marcel@redhat.com</a>> >> Message-Id: <<a href="mailto:20210802090057.1709775-1-marcel@redhat.com" target="_blank">20210802090057.1709775-1-marcel@redhat.com</a>> >> Reviewed-by: Michael S. Tsirkin <<a href="mailto:mst@redhat.com" target="_blank">mst@redhat.com</a>> >> Signed-off-by: Michael S. Tsirkin <<a href="mailto:mst@redhat.com" target="_blank">mst@redhat.com</a>> >> >> 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 >> > </blockquote></div></div>