Re: [PATCH v2 0/6] ArmVirtQemu: move to generic PciHostBridgeDxe

[Laszlo Ersek <lersek@redhat.com>]

On 09/02/16 16:58, Ard Biesheuvel wrote:
> (on the road atm, will reply in full later)
> 
>> On 2 sep. 2016, at 14:09, Laszlo Ersek <lersek@redhat.com> wrote:

>> (2) aarch64 KVM, using virtio-gpu-pci and USB 2 keyboard and
>> tablet. I actually booted a Fedora 24 guest with this, and in the
>> guest, everything works just fine (display, keyboard,
>> mouse/tablet). Most of the firmware log looks good too.
>>
>> (2a) However, the USB 2 keyboard is broken while in the firmware
>> (in spite of it working well in the guest OS).
>>
>>  -device ich9-usb-ehci1,multifunction=on,id=ehci,addr=05.0 \
>>  -device ich9-usb-uhci1,multifunction=on,masterbus=ehci.0,firstport=0,addr=05.1 \
>>  -device ich9-usb-uhci2,multifunction=on,masterbus=ehci.0,firstport=2,addr=05.2 \
>>  -device ich9-usb-uhci3,multifunction=on,masterbus=ehci.0,firstport=4,addr=05.3 \
>>  -device usb-kbd,bus=ehci.0 \
>>  -device usb-tablet,bus=ehci.0 \
>>
>> My QEMU has your commit 5d636e21c44e ("hw/arm/virt: mark the PCIe
>> host controller as DMA coherent in the DT"), but I guess the EHCI
>> driver in edk2 doesn't comply with the "guest drivers should use
>> cacheable accesses as well when running under KVM" part. :(
>>
>> The following snippet repeats in the log:
>>
>>  EhcClearLegacySupport: called to clear legacy support
>>  processing error - resetting ehci HC
>>  EhcInitHC: failed to enable period schedule
>>  EhcDriverBindingStart: failed to init host controller
>>  EhcCreateUsb2Hc: capability length 32
>>
>> Interestingly, if I back out your series, then USB2 works in the
>> firmware. I don't understand this, given that my build includes
>> commit 3ef3209d3028 ("ArmVirtPkg: remove
>> PcdKludgeMapPciMmioAsCached") from the master branch!
>>
> 
> Does it work when you limit DMA to < 4 GB?

You are one wicked genius, man; the following change

> diff --git a/ArmVirtPkg/Library/FdtPciHostBridgeLib/FdtPciHostBridgeLib.c b/ArmVirtPkg/Library/FdtPciHostBridgeLib/FdtPciHostBridgeLib.c
> index efccedcca14f..1f0f87cac8a9 100644
> --- a/ArmVirtPkg/Library/FdtPciHostBridgeLib/FdtPciHostBridgeLib.c
> +++ b/ArmVirtPkg/Library/FdtPciHostBridgeLib/FdtPciHostBridgeLib.c
> @@ -317,7 +317,7 @@ PciHostBridgeGetRootBridges (
>                                        EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO_16;
>    mRootBridge.Attributes            = mRootBridge.Supports;
>  
> -  mRootBridge.DmaAbove4G            = TRUE;
> +  mRootBridge.DmaAbove4G            = FALSE;
>    mRootBridge.NoExtendedConfigSpace = FALSE;
>    mRootBridge.ResourceAssigned      = FALSE;
>  

does make it work! Excellent!

Explain please. :) (Although, I'll look into PciHostBridgeDxe in a moment too. :))

Thank you!
Laszlo