Re: [PATCH] MdeModulePkg/AtaAtapiPassThru: disable only BM-DMA at ExitBootServices()

[Laszlo Ersek <lersek@redhat.com>]

On 11/23/17 03:20, Ni, Ruiyu wrote:
> I cannot explain precisely why the S4 resume fails.
> I can just guess: Windows might have some assumptions on the BM bit.

Can we make this configurable on the platform level somehow?

On one hand, I certainly don't want to break Windows 10, even in case
this issue ultimately turns out to be a Windows 10 bug.

On the other hand, OVMF does not support S4, and disabling BMDMA at
ExitBootServices() in PCI drivers is specifically what the Driver
Writers' Guide recommends. Otherwise pending DMA could corrupt OS memory.

So, for OVMF at least, I'd like to keep the present behavior, but for
other platforms, I don't insist on disabling BMDMA, of course.

We already have a PCD called "PcdAcpiS3Enable" in "MdeModulePkg.dec";
maybe we can introduce "PcdAcpiS4Enable" too.

BTW, has anyone reported this S4 issue to Microsoft? (Personally I'm
totally unable to talk to Microsoft -- no working communication channels
seem to be accessible to me. I hope Intel might fare better.) I wonder
what their opinion would be on the issue.

Thanks,
Laszlo

>> -----Original Message-----
>> From: Zeng, Star
>> Sent: Wednesday, November 22, 2017 6:26 PM
>> To: Ni, Ruiyu <ruiyu.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>;
>> edk2-devel-01 <edk2-devel@lists.01.org>
>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Dong, Eric
>> <eric.dong@intel.com>; Dann Frazier <dannf@ubuntu.com>; Zeng, Star
>> <star.zeng@intel.com>
>> Subject: RE: [edk2] [PATCH] MdeModulePkg/AtaAtapiPassThru: disable only
>> BM-DMA at ExitBootServices()
>>
>> Ray,
>>
>> You may explain more why Win10 S4 resume fails with only BM disabled,
>> then Laszlo can know the issue well.
>>
>>
>> Thanks,
>> Star
>> -----Original Message-----
>> From: Ni, Ruiyu
>> Sent: Wednesday, November 22, 2017 6:06 PM
>> To: Laszlo Ersek <lersek@redhat.com>; edk2-devel-01 <edk2-
>> devel@lists.01.org>
>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Dong, Eric
>> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>; Dann Frazier
>> <dannf@ubuntu.com>
>> Subject: RE: [edk2] [PATCH] MdeModulePkg/AtaAtapiPassThru: disable only
>> BM-DMA at ExitBootServices()
>>
>> Laszlo,
>> Our QA found Win10 S4 resume fails due to your change.
>> As you might notice that I just rolled back the BM disabling patches in PciBus
>> module, I am thinking about maybe you need to rollback the whole
>> ExitBootServices callback as well to fix the compatibility issue.
>>
>> Thanks/Ray
>>
>>> -----Original Message-----
>>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
>>> Laszlo Ersek
>>> Sent: Saturday, October 28, 2017 12:10 AM
>>> To: edk2-devel-01 <edk2-devel@lists.01.org>
>>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Dong, Eric
>>> <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>; Dann Frazier
>>> <dannf@ubuntu.com>
>>> Subject: Re: [edk2] [PATCH] MdeModulePkg/AtaAtapiPassThru: disable
>>> only BM-DMA at ExitBootServices()
>>>
>>> On 10/26/17 17:48, Laszlo Ersek wrote:
>>>> Clearing I/O port decoding in the PCI command register at
>>>> ExitBootServices() breaks IDE boot in Windows, on QEMU's "pc"
>>>> (i440fx) machine type. (AHCI boot on "q35" is unaffected.) Windows
>>>> seems repeatedly stuck, apparently waiting for a timeout of sorts.
>>>>
>>>> This is arguably a Windows bug; a native OS driver should not expect
>>>> the firmware to leave the PCI command register in any particular state.
>>>>
>>>> Strictly speaking, we only need to disable BM-DMA at
>>>> ExitBootServices(), in order to abort pending transfers to/from RAM,
>>>> which is soon to be owned by the OS. BM-DMA is also the only bit
>>>> that's explicitly named by the UEFI Driver Writers' Guide, for
>>>> clearing at
>>> ExitBootServices().
>>>>
>>>> I've verified that clearing only BM-DMA fixes the isse (boot time)
>>>> on i440fx, and does not regress q35/AHCI.
>>>>
>>>> Cc: Aleksei Kovura <alex3kov@zoho.com>
>>>> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> Cc: Dann Frazier <dannf@ubuntu.com>
>>>> Cc: Eric Dong <eric.dong@intel.com>
>>>> Cc: Star Zeng <star.zeng@intel.com>
>>>> Reported-by: Aleksei Kovura <alex3kov@zoho.com>
>>>> Reported-by: Dann Frazier <dannf@ubuntu.com>
>>>> Reported-by: https://launchpad.net/~cjkrupp
>>>> Bisected-by: Dann Frazier <dannf@ubuntu.com>
>>>> Bisected-by: https://launchpad.net/~cjkrupp
>>>> Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> Suggested-by: Star Zeng <star.zeng@intel.com>
>>>> Ref: https://bugs.launchpad.net/ubuntu/+source/edk2/+bug/1725560
>>>> Fixes: 6fb8ddd36bde45614b0a069528cdc97077835a74
>>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>>>> ---
>>>>
>>>> Notes:
>>>>     Repo:   https://github.com/lersek/edk2.git
>>>>     Branch: ata_disable_only_bmdma
>>>>
>>>>  MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h | 3 +--
>>>> MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c | 5 ++---
>>>>  2 files changed, 3 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git
>>>> a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h
>>>> b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h
>>>> index 8d6eac706c0b..92c5bf2001cd 100644
>>>> --- a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h
>>>> +++ b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h
>>>> @@ -123,8 +123,7 @@ typedef struct {
>>>>    LIST_ENTRY                        NonBlockingTaskList;
>>>>
>>>>    //
>>>> -  // For disabling the device (especially Bus Master DMA) at
>>>> -  // ExitBootServices().
>>>> +  // For disabling Bus Master DMA on the device at ExitBootServices().
>>>>    //
>>>>    EFI_EVENT                         ExitBootEvent;
>>>>  } ATA_ATAPI_PASS_THRU_INSTANCE;
>>>> diff --git
>>>> a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
>>>> b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
>>>> index 09064dda18b7..e10e0d4e65f6 100644
>>>> --- a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
>>>> +++ b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c
>>>> @@ -480,8 +480,7 @@ InitializeAtaAtapiPassThru (  }
>>>>
>>>>  /**
>>>> -  Disable the device (especially Bus Master DMA) when exiting the
>>>> boot
>>>> -  services.
>>>> +  Disable Bus Master DMA on the device when exiting the boot services.
>>>>
>>>>    @param[in] Event    Event for which this notification function is being
>>>>                        called.
>>>> @@ -506,7 +505,7 @@ AtaPassThruExitBootServices (
>>>>    PciIo->Attributes (
>>>>             PciIo,
>>>>             EfiPciIoAttributeOperationDisable,
>>>> -           Instance->EnabledPciAttributes,
>>>> +           Instance->EnabledPciAttributes &
>>>> + EFI_PCI_IO_ATTRIBUTE_BUS_MASTER,
>>>>             NULL
>>>>             );
>>>>  }
>>>>
>>>
>>> Thanks Everyone for the feedback; I fixed the typo pointed out by Star
>>> and pushed the patch as commit 76fd5a660d70.
>>>
>>> Cheers
>>> Laszlo
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