[RFC PATCH v2 0/2] MdeModulePkg, OvmfPkg: fixed PCI BAR placement

[Tushar Dave <tdave@nvidia.com>]

This is the EDK2 companion to the QEMU RFC v2 series [1].

This series implements the firmware side of fixed PCI BAR placement.
QEMU exports validated fixed BAR addresses through the
`etc/fixed-bars` fw_cfg file. This series consumes that information
in two steps.

Patch 1 adds minimal changes to `PciBusDxe` to honor fixed BAR
addresses supplied through `EFI_INCOMPATIBLE_PCI_DEVICE_SUPPORT_PROTOCOL`.
When both `_MIF` and `_MAF` flags are set in an ACPI address
descriptor returned by `CheckDevice()`, the described address is
treated as a fixed requirement. `UpdatePciInfo()` records the fixed
address on the BAR and `ProgramBar()` uses it in place of the
GCD-allocated address.

Patch 2 introduces `QemuFixedBarsDxe`, a new OvmfPkg driver that
installs `EFI_INCOMPATIBLE_PCI_DEVICE_SUPPORT_PROTOCOL` before
`PciBusDxe` starts. It reads the `etc/fixed-bars` fw_cfg blob,
reserves the required address ranges in the GCD, and returns fixed
BAR addresses through `CheckDevice()`. After `PciEnumerationComplete`,
it reprograms bridge memory windows along each fixed root-port
hierarchy to cover the fixed BAR placements.

Testing:

The series was tested together with the QEMU companion patches on
the AArch64 `virt` machine using multiple PCI topologies, including
emulated devices, VFIO passthrough devices, PCIe switches, and PCIe
root ports configured for fixed BAR placement.

A git branch with this series applied is available at:
https://github.com/tdavenvidia/edk2/tree/RFC-v2-fixed-bar-upstream

[1] companion QEMU RFC v2
https://github.com/tdavenvidia/upstream-qemu/tree/RFC-v2-fixed-bar-upstream

Tushar Dave (2):
  MdeModulePkg/PciBusDxe: honor fixed BAR addresses from IncompatiblePci
  ArmVirtPkg,OvmfPkg: add QemuFixedBarsDxe for fixed PCI BAR placement

 ArmVirtPkg/ArmVirtQemu.dsc                    |   1 +
 ArmVirtPkg/ArmVirtQemuFvMain.fdf.inc          |   1 +
 MdeModulePkg/Bus/Pci/PciBusDxe/PciBus.h       |   1 +
 .../Bus/Pci/PciBusDxe/PciEnumeratorSupport.c  |  12 +
 .../Bus/Pci/PciBusDxe/PciResourceSupport.c    |  13 +
 OvmfPkg/QemuFixedBarsDxe/QemuFixedBarsDxe.c   | 772 ++++++++++++++++++
 OvmfPkg/QemuFixedBarsDxe/QemuFixedBarsDxe.inf |  43 +
 7 files changed, 843 insertions(+)
 create mode 100644 OvmfPkg/QemuFixedBarsDxe/QemuFixedBarsDxe.c
 create mode 100644 OvmfPkg/QemuFixedBarsDxe/QemuFixedBarsDxe.inf

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2.34.1