MdeModulePkg/NonDiscoverablePciDeviceDxe: expose unique B/D/F identifiers

Currently, the implementation of EFI_PCI_IO_PROTOCOL::GetLocation()
in NonDiscoverablePciDeviceDxe returns the same set of dummy values
for each instance of the NON_DISCOVERABLE_DEVICE protocol that it
attaches itself to. However, this turns out to be causing problems
in cases where software (such as the ARM Compliance Test Suite [ACS])
attempts to use these values to uniquely identify controllers, since
the collisions create ambiguity in this regard.

So let's modify GetLocation() to return an arbitrary bus/device tuple
on segment 0xff instead. This is guaranteed not to clash with other
non-discoverable PCI devices, and highly unlikely to clash with real
PCIe devices.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>

MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceDxe.c

@@ -16,6 +16,9 @@
 
 #include <Protocol/DriverBinding.h>
 
+#define MAX_NON_DISCOVERABLE_PCI_DEVICE_ID   (32 * 256)
+
+STATIC UINTN               mUniqueIdCounter = 0;
 EFI_CPU_ARCH_PROTOCOL      *mCpu;
 
 //
@@ -141,6 +144,11 @@ NonDiscoverablePciDeviceStart (
   NON_DISCOVERABLE_PCI_DEVICE   *Dev;
   EFI_STATUS                    Status;
 
+  ASSERT (mUniqueIdCounter < MAX_NON_DISCOVERABLE_PCI_DEVICE_ID);
+  if (mUniqueIdCounter >= MAX_NON_DISCOVERABLE_PCI_DEVICE_ID) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
   Dev = AllocateZeroPool (sizeof *Dev);
   if (Dev == NULL) {
     return EFI_OUT_OF_RESOURCES;
@@ -167,6 +175,8 @@ NonDiscoverablePciDeviceStart (
     goto CloseProtocol;
   }
 
+  Dev->UniqueId = mUniqueIdCounter++;
+
   return EFI_SUCCESS;
 
 CloseProtocol: