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. -- MST