Reviewed-by Sean Rhodes <sean@starlabs.systems>

On Wed, 30 Mar 2022 at 19:29, Sean Rhodes <sean@starlabs.systems> wrote:

> From: Lean Sheng Tan <sheng.tan@9elements.com>
>
> Don't assume a 64bit register always holds an address greater than 4GB.
> Check the value in the register and decide which Aperature it should be
> assigned to.
>
> Fixes assertion
> "ASSERT [PciHostBridgeDxe] Bridge->MemAbove4G.Base >=
> 0x0000000100000000ULL".
>
> Tested with coreboot as bootloader on platforms that have PCI resource
> above 4GiB and on platforms that don't have resource above 4GiB.
>
> Cc: Guo Dong <guo.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Maurice Ma <maurice.ma@intel.com>
> Cc: Benjamin You <benjamin.you@intel.com>
> Cc: Sean Rhodes <sean@starlabs.systems>
> Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
> ---
>  .../Library/PciHostBridgeLib/PciHostBridgeSupport.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git
> a/UefiPayloadPkg/Library/PciHostBridgeLib/PciHostBridgeSupport.c
> b/UefiPayloadPkg/Library/PciHostBridgeLib/PciHostBridgeSupport.c
> index 8a890b6b53..e1faa24ae7 100644
> --- a/UefiPayloadPkg/Library/PciHostBridgeLib/PciHostBridgeSupport.c
> +++ b/UefiPayloadPkg/Library/PciHostBridgeLib/PciHostBridgeSupport.c
> @@ -354,14 +354,19 @@ ScanForRootBridges (
>            Base  = ((UINT32)Pci.Bridge.PrefetchableMemoryBase & 0xfff0) <<
> 16;
>            Limit = (((UINT32)Pci.Bridge.PrefetchableMemoryLimit & 0xfff0)
>                     << 16) | 0xfffff;
> -          MemAperture = &Mem;
> +
>            if (Value == BIT0) {
> -            Base       |= LShiftU64 (Pci.Bridge.PrefetchableBaseUpper32,
> 32);
> -            Limit      |= LShiftU64 (Pci.Bridge.PrefetchableLimitUpper32,
> 32);
> -            MemAperture = &MemAbove4G;
> +            Base  |= LShiftU64 (Pci.Bridge.PrefetchableBaseUpper32, 32);
> +            Limit |= LShiftU64 (Pci.Bridge.PrefetchableLimitUpper32, 32);
>            }
>
>            if ((Base > 0) && (Base < Limit)) {
> +            if (Base < BASE_4GB) {
> +              MemAperture = &Mem;
> +            } else {
> +              MemAperture = &MemAbove4G;
> +            }
> +
>              if (MemAperture->Base > Base) {
>                MemAperture->Base = Base;
>              }
> --
> 2.32.0
>
>