From 76fd5a660d704538a1b14a58d03a4eef9682b01c Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Thu, 26 Oct 2017 15:48:31 +0200 Subject: [PATCH] MdeModulePkg/AtaAtapiPassThru: disable only BM-DMA at ExitBootServices() 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 issue (boot time) on i440fx, and does not regress q35/AHCI. Cc: Aleksei Kovura Cc: Ard Biesheuvel Cc: Dann Frazier Cc: Eric Dong Cc: Star Zeng Reported-by: Aleksei Kovura Reported-by: Dann Frazier Reported-by: https://launchpad.net/~cjkrupp Bisected-by: Dann Frazier Bisected-by: https://launchpad.net/~cjkrupp Suggested-by: Ard Biesheuvel Suggested-by: Star Zeng Ref: https://bugs.launchpad.net/ubuntu/+source/edk2/+bug/1725560 Fixes: 6fb8ddd36bde45614b0a069528cdc97077835a74 Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek Tested-by: dann frazier Reviewed-by: Star Zeng Tested-by: Aleksei Kovura --- MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c | 5 ++--- MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h | 3 +-- 2 files changed, 3 insertions(+), 5 deletions(-) diff --git a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.c index 09064dda18..e10e0d4e65 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 ); } diff --git a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AtaAtapiPassThru.h index 8d6eac706c..92c5bf2001 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; -- 2.39.2