tree f644f4e236082876cc3940f2ac2c703a8c4638f6
parent a798c10faf62a505d24e5f6213fbaf904a39623f
author Bjorn Helgaas <bhelgaas@google.com> 1398270066 -0600
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1398299980 +0200

PNP: Work around BIOS defects in Intel MCH area reporting

Work around BIOSes that don't report the entire Intel MCH area.

MCHBAR is not an architected PCI BAR, so MCH space is usually reported as a
PNP0C02 resource.  The MCH space was once 16KB, but is 32KB in newer parts.
Some BIOSes still report a PNP0C02 resource that is only 16KB, which means
the rest of the MCH space is consumed but unreported.

This can cause resource map sanity check warnings or (theoretically) a
device conflict if we assigned the unreported space to another device.

The Intel perf event uncore driver tripped over this when it claimed the
MCH region:

  resource map sanity check conflict: 0xfed10000 0xfed15fff 0xfed10000 0xfed13fff pnp 00:01
  Info: mapping multiple BARs. Your kernel is fine.

To prevent this, if we find a PNP0C02 resource that covers part of the MCH
space, extend it to cover the entire space.

References: http://lkml.kernel.org/r/20140224162400.GE16457@pd.tnic
Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>