Re: [edk2-devel] [PATCH v2] MdeModulePkg: Correct high-memory use in NvmExpressDxe

["Tomas Pilar (tpilar)" <quic_tpilar@quicinc.com>]

On 24/02/2022 13:19, Tomas Pilar (tpilar) wrote:
>
>
> On 24/02/2022 13:14, Tomas Pilar (tpilar) wrote:
>>
>>
>> On 24/02/2022 13:13, Ard Biesheuvel wrote:
>>> On Thu, 24 Feb 2022 at 13:58, Tomas Pilar (tpilar)
>>> <quic_tpilar@quicinc.com> wrote:
>>>> Move the logic that sets EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE Pci
>>>>
>>>> attribute to DriverBindingStart() before the memory that backs the
>>>>
>>>> DMA engine is allocated.
>>>>
>>>>
>>>>
>>>> This ensures that the DMA-backing memory is not forcibly allocated
>>>>
>>>> below 4G in system address map. Otherwise the allocation fails on
>>>>
>>>> platforms that do not have any memory below the 4G mark and the drive
>>>>
>>>> initialisation fails.
>>>>
>>>>
>>>>
>>>> Cc: Ray Ni <ray.ni@intel.com>
>>>>
>>>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
>>>>
>>>> Cc: Leif Lindholm <leif@nuviainc.com>
>>>>
>>>> Signed-off-by: Tomas Pilar <quic_tpilar@quicinc.com>
>>> Ehm, nope, that is not exactly what I meant.
>>>
>>> The existing code stores the original PCI attributes in the controller
>>> private data, enables MMIO/IO decoding and bus mastering, and only
>>> then sets the dual address cycle attribute.
>>>
>>> All of that needs to move, so that the captured attributes are 
>>> accurate.
>>>
>>>
>> Okay, I was wondering. My thought was that we probably want to 
>> re-enable bus mastering
>> on reset so I kept that bit of code in the original location.
>>
>
> Also, doesn't this code:
>
>   if (!EFI_ERROR (Status)) {
>     Supports &= (UINT64)EFI_PCI_DEVICE_ENABLE;
>     Status    = PciIo->Attributes (
>                          PciIo,
>                          EfiPciIoAttributeOperationEnable,
>                          Supports,
>                          NULL
>                          );
>   }
>
> *strip* the PCI_DEVICE_ENABLE set of attributes rather than add them? 
> I am somewhat confused about this.
>
Wait no. I just cannot read code, ignore that last bit. I'll prepare a 
patch.