[RFC v4 3/3] MdeModulePkg/PciBus: return CPU address for GetBarAttributes

[Heyi Guo <heyi.guo@linaro.org>]

According to UEFI spec 2.7, PciIo->GetBarAttributes should return host
address (CPU view ddress) rather than device address (PCI view
address), and
device address = host address + address translation offset,
so we subtract translation from device address before returning.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
---
 MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c
index fef3eceb7f62..62179eb44bbd 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciIo.c
@@ -1972,6 +1972,10 @@ PciIoGetBarAttributes (
         return EFI_UNSUPPORTED;
       }
     }
+
+    // According to UEFI spec 2.7, we need return host address for
+    // PciIo->GetBarAttributes, and host address = device address - translation.
+    Descriptor->AddrRangeMin -= Descriptor->AddrTranslationOffset;
   }
 
   return EFI_SUCCESS;
-- 
2.7.4