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

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

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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