On Wed, May 20, 2020 at 11:56:26AM +0200, Igor Mammedow wrote: > On Wed, 20 May 2020 05:47:53 -0400 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > On Wed, May 20, 2020 at 11:43:54AM +0200, Igor Mammedow wrote: > > > On Fri, 15 May 2020 12:13:53 +0000 > > > Ani Sinha <ani.si...@nutanix.com> wrote: > > > > > > > > On May 14, 2020, at 1:13 AM, Igor Mammedov <imamm...@redhat.com> > > > > > wrote: > > > > >> > > > > >> > > > > >>> Will following hack work for you? > > > > >>> possible permutations > > > > >>> 1) ACPI hotplug everywhere > > > > >>> -global PIIX4_PM.acpi-pci-hotplug=on -global > > > > >>> PIIX4_PM.acpi-pci-hotplug-with-bridge-support=on -device > > > > >>> pci-bridge,chassis_nr=1,shpc=doesnt_matter -device > > > > >>> e1000,bus=pci.1,addr=01,id=netdev1 > > > > >>> > > > > >>> 2) No hotplug at all > > > > >>> -global PIIX4_PM.acpi-pci-hotplug=off -global > > > > >>> PIIX4_PM.acpi-pci-hotplug-with-bridge-support=on -device > > > > >>> pci-bridge,chassis_nr=1,shpc=off -device > > > > >>> e1000,bus=pci.1,addr=01,id=netdev1 > > > > >>> > > > > >>> -global PIIX4_PM.acpi-pci-hotplug=off -global > > > > >>> PIIX4_PM.acpi-pci-hotplug-with-bridge-support=off -device > > > > >>> pci-bridge,chassis_nr=1,shpc=doesnt_matter -device > > > > >>> e1000,bus=pci.1,addr=01,id=netdev1 > > > > >> > > > > >> Given that my patch is not acceptable, I’d prefer the > > > > >> following in the order of preference: > > > > >> > > > > >> (a) Have an option to disable hot ejection of PCI-PCI bridge so > > > > >> that Windows does not even show this HW in the “safely remove > > > > >> HW” option. If we can do this then from OS perspective the GUI > > > > >> options will be same as what is available with PCIE/q35 - none > > > > >> of the devices will be hot ejectable if the hot plug option is > > > > >> turned off from the PCIE slots where devices are plugged into. > > > > >> I looked at the code. It seems to manipulate ACPI tables of > > > > >> the empty slots of the root bus where no devices are attached > > > > >> (see comment "/* add hotplug slots for non present devices */ > > > > >> “). For cold plugged bridges, it recurses down to scan the > > > > >> slots of the bridge. Is it possible to disable hot plug for > > > > >> the slot to which the bridge is attached? > > > > > > > > > > I don't think it's possible to have per slot hotplug on > > > > > conventional PCI hardware. it's per bridge property. > > > > > > > > We add the AMLs per empty slot though. When the pic bridge is > > > > attached, we do nothing, just recurse into the bridge slots. That > > > > is what I was asking, if it was possible to just disable the AMLs > > > > or use some tricks to say that this particular slot is not > > > > hotpluggable. I am not sure why Windows is trying to eject the > > > > PCI bridge and failing. Maybe something related to this comment? > > > > > > > > > > > > /* When hotplug for bridges is enabled, bridges are > > > > > > > > * described in ACPI separately (see build_pci_bus_end). > > > > > > > > * In this case they aren't themselves hot-pluggable. > > > > > > > > * Hotplugged bridges *are* hot-pluggable. > > > > */ > > > > > > thinking some more on this topic, it seems that with ACPI hotplug we > > > already have implicit non-hotpluggble slot (slot with bridge) while > > > the rest are staying hotpluggable. > > > > > > So my question is: if it's acceptable to add > > > 'PCIDevice::hotpluggable" property to all PCI devices so that user > > > / libvirt could set it to false in case they do not want > > > coldplugged device be considered as hotpluggable? (this way other > > > devices could be treated the same way as bridges) > > > > > > [...] > > > > > > I think Julia already posted a patch adding this to downstream pcie > > bridges. Adding this to pci slots sounds like a reasonable thing. > Question was more about external interface, were we do not have ports > as separate devices with conventional PCI. The only knob we have is a > a PCI device, where we have a property to turn on/off hotplug. ex: > -device e1000,hotpluggable=off > and if libvirt would be able to use it
Libvirt can certainly use a property that is settable per-device, instead of against the pcie-root-port. In fact the application that requested hotplug control (KubeVirt) would strongly prefer if this was doable per-device, because they really dislike the idea of having to deal with pcie-root-port devices. So if you added it per-device, libvirt would support both the per-device option, and the pcie-root-port option. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
