Re: [PATCH 6/7] MdeModulePkg/PciHostBridgeDxe: restrict 64-bit DMA to devices that support it

[Laszlo Ersek <lersek@redhat.com>]

On 09/05/16 11:17, Ard Biesheuvel wrote:
> Currently, the EFI_PCI_ATTRIBUTE_DUAL_ADDRESS_CYCLE attribute is completely
> ignored by the PCI host bridge driver, which means that, on an implementation
> that supports DMA above 4 GB, allocations above 4 GB may be provided to
> devices that have not expressed support for it.
> 
> So in addition to checking 'RootBridge->DmaAbove4G' to establish whether the
> root bridge itself supports DMA above 4 GB, we must also take into account
> the operation type (EfiPciOperationBusMaster{Read|Write|CommBuffer}64),
> and the EFI_PCI_ATTRIBUTE_DUAL_ADDRESS_CYCLE attribute, when mapping and
> allocating DMA memory, respectively.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> index b2d76d67afa2..8af131b0af37 100644
> --- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> +++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> @@ -1073,10 +1073,15 @@ RootBridgeIoMap (
>    RootBridge = ROOT_BRIDGE_FROM_THIS (This);
>  
>    PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress;
> -  if (!RootBridge->DmaAbove4G && ((PhysicalAddress + *NumberOfBytes) > SIZE_4GB)) {
> +  if ((!RootBridge->DmaAbove4G ||
> +       (Operation != EfiPciOperationBusMasterRead64 &&
> +        Operation != EfiPciOperationBusMasterWrite64 &&
> +        Operation != EfiPciOperationBusMasterCommonBuffer64)) &&
> +      ((PhysicalAddress + *NumberOfBytes) > SIZE_4GB)) {
> +
>      //
> -    // If the root bridge can not handle performing DMA above 4GB but
> -    // any part of the DMA transfer being mapped is above 4GB, then
> +    // If the root bridge or the device cannot handle performing DMA above
> +    // 4GB but any part of the DMA transfer being mapped is above 4GB, then
>      // map the DMA transfer to a buffer below 4GB.
>      //
>  
> @@ -1308,7 +1313,8 @@ RootBridgeIoAllocateBuffer (
>    RootBridge = ROOT_BRIDGE_FROM_THIS (This);
>  
>    AllocateType = AllocateAnyPages;
> -  if (!RootBridge->DmaAbove4G) {
> +  if (!RootBridge->DmaAbove4G ||
> +      (Attributes & EFI_PCI_ATTRIBUTE_DUAL_ADDRESS_CYCLE) == 0) {
>      //
>      // Limit allocations to memory below 4GB
>      //
> 

Reviewed-by: Laszlo Ersek <lersek@redhat.com>