On Wed, 2023-11-01 at 17:20 -0500, Bjorn Helgaas wrote: > On Tue, Oct 31, 2023 at 12:59:34PM -0700, Nirmal Patel wrote: > > On Tue, 2023-10-31 at 10:31 -0500, Bjorn Helgaas wrote: > > > On Mon, Oct 30, 2023 at 04:16:54PM -0400, Nirmal Patel wrote: > > > > VMD Hotplug should be enabled or disabled based on VMD > > > > rootports' > > > > Hotplug configuration in BIOS. is_hotplug_bridge is set on each > > > > VMD rootport based on Hotplug capable bit in SltCap in probe.c. > > > > Check is_hotplug_bridge and enable or disable > > > > native_pcie_hotplug > > > > based on that value. > > > > > > > > Currently VMD driver copies ACPI settings or platform > > > > configurations > > > > for Hotplug, AER, DPC, PM, etc and enables or disables these > > > > features > > > > on VMD bridge which is not correct in case of Hotplug. > > > > > > This needs some background about why it's correct to copy the > > > ACPI > > > settings in the case of AER, DPC, PM, etc, but incorrect for > > > hotplug. > > > > > > > Also during the Guest boot up, ACPI settings along with VMD > > > > UEFI > > > > driver are not present in Guest BIOS which results in assigning > > > > default values to Hotplug, AER, DPC, etc. As a result Hotplug > > > > is > > > > disabled on VMD in the Guest OS. > > > > > > > > This patch will make sure that Hotplug is enabled properly in > > > > Host > > > > as well as in VM. > > > > > > Did we come to some consensus about how or whether _OSC for the > > > host > > > bridge above the VMD device should apply to devices in the > > > separate > > > domain below the VMD? > > > > We are not able to come to any consensus. Someone suggested to copy > > either all _OSC flags or none. But logic behind that assumption is > > that the VMD is a bridge device which is not completely true. VMD > > is an > > endpoint device and it owns its domain. > > Do you want to facilitate a discussion in the PCI firmware SIG about > this? It seems like we may want a little text in the spec about how > to handle this situation so platforms and OSes have the same > expectations. The patch 04b12ef163d1 broke intel VMD's hotplug capabilities and author did not test in VM environment impact. We can resolve the issue easily by #1 Revert the patch which means restoring VMD's original functionality and author provide better fix. or #2 Allow the current change to re-enable VMD hotplug inside VMD driver. There is a significant impact for our customers hotplug use cases which forces us to apply the fix in out-of-box drivers for different OSs. nirmal > > Bjorn
