This reverts commit 4c5e242d.

Prior to 4c5e242d ("x86/PCI: Clip only host bridge windows for E820
regions"), E820 regions did not affect PCI host bridge windows.  We only
looked at E820 regions and avoided them when allocating new MMIO space.
If firmware PCI bridge window and BAR assignments used E820 regions, we
left them alone.

After 4c5e242d, we removed E820 regions from the PCI host bridge
windows before looking at BARs, so firmware assignments in E820 regions
looked like errors, and we moved things around to fit in the space left
(if any) after removing the E820 regions.  This unnecessary BAR
reassignment broke several machines.

Guilherme reported that Steam Deck fails to boot after 4c5e242d.  We
clipped the window that contained most 32-bit BARs:

  BIOS-e820: [mem 0x00000000a0000000-0x00000000a00fffff] reserved
  acpi PNP0A08:00: clipped [mem 0x80000000-0xf7ffffff window] to [mem 0xa0100000-0xf7ffffff window] for e820 entry [mem 0xa0000000-0xa00fffff]

which forced us to reassign all those BARs, for example, this NVMe BAR:

  pci 0000:00:01.2: PCI bridge to [bus 01]
  pci 0000:00:01.2:   bridge window [mem 0x80600000-0x806fffff]
  pci 0000:01:00.0: BAR 0: [mem 0x80600000-0x80603fff 64bit]
  pci 0000:00:01.2: can't claim window [mem 0x80600000-0x806fffff]: no compatible bridge window
  pci 0000:01:00.0: can't claim BAR 0 [mem 0x80600000-0x80603fff 64bit]: no compatible bridge window

  pci 0000:00:01.2: bridge window: assigned [mem 0xa0100000-0xa01fffff]
  pci 0000:01:00.0: BAR 0: assigned [mem 0xa0100000-0xa0103fff 64bit]

All the reassignments were successful, so the devices should have been
functional at the new addresses, but some were not.

Andy reported a similar failure on an Intel MID platform.  Benjamin
reported a similar failure on a VMWare Fusion VM.

Note: this is not a clean revert; this revert keeps the later change to
make the clipping dependent on a new pci_use_e820 bool, moving the checking
of this bool to arch_remove_reservations().

[bhelgaas: commit log, add more reporters and testers]
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=216109Reported-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reported-by: Benjamin Coddington <bcodding@redhat.com>
Reported-by: Jongman Heo <jongman.heo@gmail.com>
Fixes: 4c5e242d ("x86/PCI: Clip only host bridge windows for E820 regions")
Link: https://lore.kernel.org/r/20220612144325.85366-1-hdegoede@redhat.comTested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>