Re: [PATCH] MdeModulePkg/NonDiscoverablePciDeviceDxe: expose unique B/D/F identifiers

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Hi Star,

On 10 October 2018 at 10:08, Zeng, Star <star.zeng@intel.com> wrote:
> Two minor comments.
> 1. Is it better to initialize mUniqueIdCounter to 0?

The C standard guarantees that it is initialized to 0 so this is unnecessary

> 2. With this patch, the Bus value returned may be > 0xFF, right? Should the code restrict the Bus value to be <= 0xFF?
>

That will happen if we register more than 32 * 256 == 8192
non-discoverable PCI devices. That is unlikely ever to occur, but it
makes sense to add an ASSERT for it and return an error, I suppose.

I will change that.

>
> Thanks,
> Star
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Ard Biesheuvel
> Sent: Tuesday, October 9, 2018 10:01 PM
> To: edk2-devel@lists.01.org
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: [edk2] [PATCH] MdeModulePkg/NonDiscoverablePciDeviceDxe: expose unique B/D/F identifiers
>
> Currently, the implementation of EFI_PCI_IO_PROTOCOL::GetLocation()
> in NonDiscoverablePciDeviceDxe returns the same set of dummy values
> for each instance of the NON_DISCOVERABLE_DEVICE protocol that it
> attaches itself to. However, this turns out to be causing problems
> in cases where software (such as the ARM Compliance Test Suite [ACS])
> attempts to use these values to uniquely identify controllers, since
> the collisions create ambiguity in this regard.
>
> So let's modify GetLocation() to return an arbitrary bus/device tuple
> on segment 0xff instead. This is guaranteed not to clash with other
> non-discoverable PCI devices, and highly unlikely to clash with real
> PCIe devices.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceDxe.c |  4 ++++
>  MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c  | 10 +++++++---
>  MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.h  |  6 ++++++
>  3 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceDxe.c b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceDxe.c
> index 3e9ff6620d8d..ed5256f3c7ea 100644
> --- a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceDxe.c
> +++ b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceDxe.c
> @@ -18,6 +18,8 @@
>
>  EFI_CPU_ARCH_PROTOCOL      *mCpu;
>
> +STATIC UINTN mUniqueIdCounter;
> +
>  //
>  // We only support the following device types
>  //
> @@ -167,6 +169,8 @@ NonDiscoverablePciDeviceStart (
>      goto CloseProtocol;
>    }
>
> +  Dev->UniqueId = mUniqueIdCounter++;
> +
>    return EFI_SUCCESS;
>
>  CloseProtocol:
> diff --git a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c
> index 0e42ae4bf6ec..58cb5d8b1fc5 100644
> --- a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c
> +++ b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.c
> @@ -1181,6 +1181,8 @@ PciIoGetLocation (
>    OUT  UINTN                *FunctionNumber
>    )
>  {
> +  NON_DISCOVERABLE_PCI_DEVICE         *Dev;
> +
>    if (SegmentNumber == NULL ||
>        BusNumber == NULL ||
>        DeviceNumber == NULL ||
> @@ -1188,9 +1190,11 @@ PciIoGetLocation (
>      return EFI_INVALID_PARAMETER;
>    }
>
> -  *SegmentNumber  = 0;
> -  *BusNumber      = 0xff;
> -  *DeviceNumber   = 0;
> +  Dev = NON_DISCOVERABLE_PCI_DEVICE_FROM_PCI_IO(This);
> +
> +  *SegmentNumber  = 0xff;
> +  *BusNumber      = Dev->UniqueId >> 5;
> +  *DeviceNumber   = Dev->UniqueId & 0x1f;
>    *FunctionNumber = 0;
>
>    return EFI_SUCCESS;
> diff --git a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.h b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.h
> index e641189267ee..5b4c57fa2a8e 100644
> --- a/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.h
> +++ b/MdeModulePkg/Bus/Pci/NonDiscoverablePciDeviceDxe/NonDiscoverablePciDeviceIo.h
> @@ -100,6 +100,12 @@ typedef struct {
>    // on behalf of this device
>    //
>    LIST_ENTRY                UncachedAllocationList;
> +  //
> +  // Unique ID for this device instance: needed so that we can report unique
> +  // segment/bus/device number for each device instance. Note that this number
> +  // may change when disconnecting/reconnecting the driver.
> +  //
> +  UINTN                     UniqueId;
>  } NON_DISCOVERABLE_PCI_DEVICE;
>
>  /**
> --
> 2.17.1
>
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