[RFC v2 0/7] PCI: hv: Support host bridge probing on ARM64

[Boqun Feng]

Hi Bjorn, Arnd and Marc,

This is the updated version of my first try to prepare for virtual PCI
support on Hyper-V ARM64:

	https://lore.kernel.org/lkml/20210319161956.2838291-1-boqun.feng@gmail.com/

, thanks a lot for your suggestions in the previous one.

This is still more an RFC, and trying to see what I'm on the correct
direction.

The basic problem we need to resolve is that ARM64 is an arch with
PCI_DOMAINS_GENERIC=y, so the bus sysdata is pci_config_window. However,
Hyper-V PCI provides a paravirtualized PCI interface, so there is no
actual pci_config_window for a PCI host bridge, so no information can be
retrieve from the pci_config_window of a Hyper-V virtual PCI bus.

This patchset mainly handle three things:

1)	PCI domain number. As suggested by Bjorn and Arnd, I introduce
	a member in pci_host_bridge, and Hyper-V can use it to set up
	the correct PCI domain number for the bus, while others remain
	the same behavior.

2)	MSI irq_domain. As suggested by Arnd, I use the
	GENERIC_MSI_IRQ_DOMAIN's dev_{set,get}_msi_domain() to allow
	Hyper-V set up the msi domain using generic code.

3)	pcibios_root_bridge_prepare(). This one is new, PCI core will
	call this during host bridge register, and it will access the
	pci_config_window, luckily the only field it accesses it the
	parent field, and I change the ARM64's behavior to treat the
	acpi device as NULL if pci_config_window::parent is NULL, so
	that Hyper-V can provide a all-zeroed pci_config_window.

With the above, we could enable the virtual PCI on Hyper-V ARM64 guest
with other code under development.

Comments and suggestions are welcome.

Regards,
Boqun

Arnd Bergmann (1):
  PCI: hv: Generify PCI probing

Boqun Feng (6):
  PCI: Introduce pci_host_bridge::domain_nr
  PCI: Allow msi domain set-up at host probing time
  PCI: hv: Use pci_host_bridge::domain_nr for PCI domain
  PCI: hv: Set up msi domain at bridge probing time
  PCI: arm64: Allow pci_config_window::parent to be NULL
  PCI: hv: Turn on the host bridge probing on ARM64

 arch/arm/kernel/bios32.c              |  2 +
 arch/arm/mach-dove/pcie.c             |  2 +
 arch/arm/mach-mv78xx0/pcie.c          |  2 +
 arch/arm/mach-orion5x/pci.c           |  2 +
 arch/arm64/kernel/pci.c               |  5 +-
 arch/mips/pci/pci-legacy.c            |  2 +
 arch/mips/pci/pci-xtalk-bridge.c      |  2 +
 drivers/pci/controller/pci-ftpci100.c |  2 +
 drivers/pci/controller/pci-hyperv.c   | 90 +++++++++++++++------------
 drivers/pci/controller/pci-mvebu.c    |  2 +
 drivers/pci/pci.c                     |  4 +-
 drivers/pci/probe.c                   | 12 +++-
 include/linux/pci.h                   | 11 +++-
 13 files changed, 89 insertions(+), 49 deletions(-)

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2.30.2