New subject: [PATCH] Platforms/AMD: remove bogus 4 GB limit in PciHostBridgeDxe

15 Apr 2016

The copy-pasted PciHostBridgeDxe driver has some interesting restrictions
that are difficult to fulfil on Seattle, i.e., its AllocateBuffer() and
IoMap() operations require the DMA address to be below 4 GB. This would
only makes sense in the presence of 32-bit only DMA bus masters that are
not behind a SMMU, but in the Seattle case, it is completely pointless
since it does not have any RAM below 4 GB in the first place.
So simply drop these restrictions.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org
---
 .../Drivers/PciHostBridgeDxe/PciRootBridgeIo.c     | 91 +---------------------
 1 file changed, 2 insertions(+), 89 deletions(-)

diff --git a/Platforms/AMD/Styx/Drivers/PciHostBridgeDxe/PciRootBridgeIo.c b/Platforms/AMD/Styx/Drivers/PciHostBridgeDxe/PciRootBridgeIo.c
index 4ac89fb7548f..941c330a4228 100644
--- a/Platforms/AMD/Styx/Drivers/PciHostBridgeDxe/PciRootBridgeIo.c
+++ b/Platforms/AMD/Styx/Drivers/PciHostBridgeDxe/PciRootBridgeIo.c
@@ -1715,89 +1715,7 @@ DEBUG((EFI_D_ERROR, "RootBridgeIoMap() - %d\n", __LINE__));
     return EFI_INVALID_PARAMETER;
   }
-  //
-  // Most PCAT like chipsets can not handle performing DMA above 4GB.
-  // If any part of the DMA transfer being mapped is above 4GB, then
-  // map the DMA transfer to a buffer below 4GB.
-  //
-  PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress;
-  if ((PhysicalAddress + *NumberOfBytes) > 0x100000000ULL) {
-
-    //
-    // Common Buffer operations can not be remapped.  If the common buffer
-    // if above 4GB, then it is not possible to generate a mapping, so return 
-    // an error.
-    //
-    if (Operation == EfiPciOperationBusMasterCommonBuffer || Operation == EfiPciOperationBusMasterCommonBuffer64) {
-      return EFI_UNSUPPORTED;
-    }
-
-    //
-    // Allocate a MAP_INFO structure to remember the mapping when Unmap() is
-    // called later.
-    //
-    Status = gBS->AllocatePool (
-                    EfiBootServicesData, 
-                    sizeof(MAP_INFO), 
-                    (VOID **)&MapInfo
-                    );
-    if (EFI_ERROR (Status)) {
-      *NumberOfBytes = 0;
-      return Status;
-    }
-
-    //
-    // Return a pointer to the MAP_INFO structure in Mapping
-    //
-    *Mapping = MapInfo;
-
-    //
-    // Initialize the MAP_INFO structure
-    //
-    MapInfo->Operation         = Operation;
-    MapInfo->NumberOfBytes     = *NumberOfBytes;
-    MapInfo->NumberOfPages     = EFI_SIZE_TO_PAGES(*NumberOfBytes);
-    MapInfo->HostAddress       = PhysicalAddress;
-    MapInfo->MappedHostAddress = 0x00000000ffffffff;
-
-    //
-    // Allocate a buffer below 4GB to map the transfer to.
-    //
-    Status = gBS->AllocatePages (
-                    AllocateMaxAddress, 
-                    EfiBootServicesData, 
-                    MapInfo->NumberOfPages,
-                    &MapInfo->MappedHostAddress
-                    );
-    if (EFI_ERROR (Status)) {
-      gBS->FreePool (MapInfo);
-      *NumberOfBytes = 0;
-      return Status;
-    }
-
-    //
-    // If this is a read operation from the Bus Master's point of view,
-    // then copy the contents of the real buffer into the mapped buffer
-    // so the Bus Master can read the contents of the real buffer.
-    //
-    if (Operation == EfiPciOperationBusMasterRead || Operation == EfiPciOperationBusMasterRead64) {
-      CopyMem (
-        (VOID *)(UINTN)MapInfo->MappedHostAddress, 
-        (VOID *)(UINTN)MapInfo->HostAddress,
-        MapInfo->NumberOfBytes
-        );
-    }
-
-    //
-    // The DeviceAddress is the address of the maped buffer below 4GB
-    //
-    *DeviceAddress = MapInfo->MappedHostAddress;
-  } else {
-    //
-    // The transfer is below 4GB, so the DeviceAddress is simply the HostAddress
-    //
-    *DeviceAddress = PhysicalAddress;
-  }
+  *DeviceAddress = PhysicalAddress;
return EFI_SUCCESS;
 }
@@ -1917,12 +1835,7 @@ DEBUG((EFI_D_ERROR, "RootBridgeIoAllocateBuffer() - %d\n", __LINE__));
     return EFI_INVALID_PARAMETER;
   }
-  //
-  // Limit allocations to memory below 4GB
-  //
-  PhysicalAddress = (EFI_PHYSICAL_ADDRESS)(0xffffffff);
-
-  Status = gBS->AllocatePages (AllocateMaxAddress, MemoryType, Pages, &PhysicalAddress);
+  Status = gBS->AllocatePages (AllocateAnyPages, MemoryType, Pages, &PhysicalAddress);
   if (EFI_ERROR (Status)) {
     return Status;
   }
-- 
2.5.0


    