Add PciResourcesPreAssigned config flag to skip PCI bus enumeration#78
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Pull request overview
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Adds support for disabling PCI bus enumeration via a platform configuration flag, wiring it through PCDs and exposing the control bit in the BIOS interface flags.
Changes:
- Introduces use of
gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumerationin Platform PEI. - Sets the new PCD based on
UEFI_CONFIG_FLAGS.Flags.PciResourcesPreAssigned. - Extends
UEFI_CONFIG_FLAGSwith new flag bits and updates default PCD values in DSCs.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| MsvmPkg/PlatformPei/PlatformPei.inf | Declares the module’s consumption of PcdPciDisableBusEnumeration. |
| MsvmPkg/PlatformPei/Config.c | Sets PcdPciDisableBusEnumeration from a UEFI config flag. |
| MsvmPkg/MsvmPkgX64.dsc | Adds default value for PcdPciDisableBusEnumeration (FALSE). |
| MsvmPkg/MsvmPkgAARCH64.dsc | Adds default value for PcdPciDisableBusEnumeration (FALSE). |
| MsvmPkg/Include/BiosInterface.h | Adds new bitfields including PciResourcesPreAssigned. |
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When the VMM has pre-assigned PCI bus numbers and BAR addresses, it sets the PciResourcesPreAssigned flag in UEFI_CONFIG_FLAGS. PlatformPei reads this flag and sets PcdPciDisableBusEnumeration to TRUE, causing PciBusDxe to use its PciEnumeratorLight() path which discovers devices and reads their existing BAR values without reallocating resources. Also adds placeholder bits for HvSintEnabled (bit 30) and VmbusDisabled (bit 31) to keep the config flags layout in sync with other branches.
Member
Author
maheeraeron
approved these changes
Jun 1, 2026
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When the VMM has pre-assigned PCI bus numbers and BAR addresses, it sets the PciResourcesPreAssigned flag in UEFI_CONFIG_FLAGS. PlatformPei reads this flag and sets PcdPciDisableBusEnumeration to TRUE, causing PciBusDxe to use its PciEnumeratorLight() path which discovers devices and reads their existing BAR values without reallocating resources.
Also adds placeholder bits for HvSintEnabled (bit 30) and VmbusDisabled (bit 31) to keep the config flags layout in sync with other branches.