On Tue, Mar 08, 2022 at 09:57:04PM +0530, Ani Sinha wrote: > > > On Tue, Mar 8, 2022 at 21:21 Laine Stump <laine@xxxxxxxxxx> wrote: > > Aha! the domain of qemu-devel@xxxxxxxxxx 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 <acpi-hotplug-bridge> 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 <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 <jusual@xxxxxxxxxx> > >> 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 <jusual@xxxxxxxxxx> > >> Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx> > >> Message-Id: <20211112110857.3116853-5-imammedo@xxxxxxxxxx> > >> Reviewed-by: Ani Sinha <ani@xxxxxxxxxxx> > >> Reviewed-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >> > >> > >> 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 <jusual@xxxxxxxxxx> > >> 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 <jusual@xxxxxxxxxx> > >> Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx> > >> Message-Id: <20211112110857.3116853-3-imammedo@xxxxxxxxxx> > >> Reviewed-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >> > >> 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 <marcel.apfelbaum@xxxxxxxxx> > >> 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 <imammedo@xxxxxxxxxx> > >> Signed-off-by: Marcel Apfelbaum <marcel@xxxxxxxxxx> > >> Message-Id: <20210802090057.1709775-1-marcel@xxxxxxxxxx> > >> Reviewed-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >> > >> 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 > >> > > > >
