Re: [PATCH] MdeModulePkg/PciHostBridge: Update Mem and PMem Limit Checks

["Ni, Ray" <ray.ni@intel.com>]

Thanks for fixing the check.

PCI_ROOT_BRIDGE_APERTURE.Base/Limit are device address while the memory space
in GCD belongs to host domain.
So, host address for Mem/Pmem should be below 4GB while device address can across
4GB.

Can you enhance the check as below?
  ASSERT (TO_HOST_ADDRESS (Bridge->Mem.Limit, Bridge->Mem.Translation) < SIZE_4GB);
  if (TO_HOST_ADDRESS (Bridge->Mem.Limit, Bridge->Mem.Translation) >= SIZE_4GB) {
    return NULL;
  }

It will look more precise and can detect invalid Mem/Pmem resource.

> -----Original Message-----
> From: Wasim Khan <wasim.khan@nxp.com>
> Sent: Thursday, April 23, 2020 6:44 PM
> To: devel@edk2.groups.io
> Cc: ard.biesheuvel@linaro.org; v.sethi@nxp.com; Wu, Hao A <hao.a.wu@intel.com>; Ni, Ray <ray.ni@intel.com>; Wasim
> Khan <wasim.khan@nxp.com>
> Subject: [PATCH] MdeModulePkg/PciHostBridge: Update Mem and PMem Limit Checks
> 
> With Address Translation Support, it is possible and
> also correct that Mem and Pmem Limit cross the 4GB boundary.
> Update the checks so that Mem/PMem Limit should not cross 4GB
> from the Mem/PMem Base address.
> 
> Signed-off-by: Wasim Khan <wasim.khan@nxp.com>
> ---
>  MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> index d304fae..9cf7e98 100644
> --- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> +++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> @@ -117,8 +117,8 @@ CreateRootBridge (
>    // Make sure Mem and MemAbove4G apertures are valid
>    //
>    if (RESOURCE_VALID (&Bridge->Mem)) {
> -    ASSERT (Bridge->Mem.Limit < SIZE_4GB);
> -    if (Bridge->Mem.Limit >= SIZE_4GB) {
> +    ASSERT (Bridge->Mem.Limit < (Bridge->Mem.Base + SIZE_4GB));
> +    if (Bridge->Mem.Limit >= (Bridge->Mem.Base + SIZE_4GB)) {
>        return NULL;
>      }
>    }
> @@ -129,8 +129,8 @@ CreateRootBridge (
>      }
>    }
>    if (RESOURCE_VALID (&Bridge->PMem)) {
> -    ASSERT (Bridge->PMem.Limit < SIZE_4GB);
> -    if (Bridge->PMem.Limit >= SIZE_4GB) {
> +    ASSERT (Bridge->PMem.Limit < (Bridge->PMem.Base + SIZE_4GB));
> +    if (Bridge->PMem.Limit >= (Bridge->PMem.Base + SIZE_4GB)) {
>        return NULL;
>      }
>    }
> --
> 2.7.4