On Thu, Feb 24, 2022 at 12:44:07PM -0500, Igor Mammedov wrote: > Currently ACPI PCI hotplug is enabled by default for Q35 machine > type and overrides native PCIe hotplug. It works as expected when > a PCIe device is hotplugged into slot, however the device becomes > in-operational after migration. Which is caused by BARs being > disabled on target due to powered off status of the slot. > > Proposed fix disables power control on PCIe slot when ACPI pcihp > takes over hotplug control and makes PCIe slot check if power > control is enabled before trying to change slot's power. Which > leaves slot always powered on and that makes PCI core keep BARs > enabled. > > PS: > it's still hacky approach as all ACPI PCI hotplug is, but it's > the least intrusive one. Alternative, I've considered, could be > chaining hotplug callbacks and making pcihp ones call overriden > native callbacks while inhibiting hotplug event in native callbacks > somehow. But that were a bit more intrusive and spills over to SHPC > if implemented systematically, so I ditched that for now. It could > be resurrected later on if current approach turns out to be > insufficient.
Yes, I am wondering about this myself. Replace callbacks with some kind of notifier, so instead of overrides we add things? I will ponder this over the weekend. > RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=2053584 > CC: m...@redhat.com > CC: kra...@redhat.com > > Igor Mammedov (4): > pci: expose TYPE_XIO3130_DOWNSTREAM name > pcie: update slot power status only is power control is enabled > acpi: pcihp: disable power control on PCIe slot > q35: compat: keep hotplugged PCIe device broken after migration for > 6.2-older machine types > > include/hw/acpi/pcihp.h | 4 +++- > include/hw/pci-bridge/xio3130_downstream.h | 15 +++++++++++++++ > hw/acpi/acpi-pci-hotplug-stub.c | 3 ++- > hw/acpi/ich9.c | 21 ++++++++++++++++++++- > hw/acpi/pcihp.c | 16 +++++++++++++++- > hw/acpi/piix4.c | 3 ++- > hw/core/machine.c | 4 +++- > hw/pci-bridge/xio3130_downstream.c | 3 ++- > hw/pci/pcie.c | 5 ++--- > 9 files changed, 64 insertions(+), 10 deletions(-) > create mode 100644 include/hw/pci-bridge/xio3130_downstream.h > > -- > 2.31.1
