Re: [edk2-devel] [PATCH] UefiCpuPkg: support single EFI_PEI_CORE_FV_LOCATION_PPI in PpiList

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

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Chiu, Chasel
> Sent: Wednesday, September 4, 2019 1:56 AM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>
> Subject: [edk2-devel] [PATCH] UefiCpuPkg: support single EFI_PEI_CORE_FV_LOCATION_PPI in PpiList
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2153
> 
> Current logic will skip searching EFI_PEI_CORE_FV_LOCATION_PPI when the
> PPI in PpiList having EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST flag,
> but platform may pass single PPI in PpiList that should be supported.
> 
> Changed the logic to verify PpiList first before checking
> EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST flag.
> 
> Test: Verified single EFI_PEI_CORE_FV_LOCATION_PPI in PpiList and
>       still can boot with the PeiCore specified by above PPI.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Signed-off-by: Chasel Chiu <chasel.chiu@intel.com>
> ---
>  UefiCpuPkg/SecCore/SecMain.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/UefiCpuPkg/SecCore/SecMain.c b/UefiCpuPkg/SecCore/SecMain.c
> index 66c952b897..6beb025b4b 100644
> --- a/UefiCpuPkg/SecCore/SecMain.c
> +++ b/UefiCpuPkg/SecCore/SecMain.c
> @@ -238,9 +238,8 @@ SecStartupPhase2(
>    // is enabled.
>    //
>    if (PpiList != NULL) {
> -    for (Index = 0;
> -      (PpiList[Index].Flags & EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST) != EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST;
> -      Index++) {
> +    Index = 0;
> +    do {
>        if (CompareGuid (PpiList[Index].Guid, &gEfiPeiCoreFvLocationPpiGuid) &&
>            (((EFI_PEI_CORE_FV_LOCATION_PPI *) PpiList[Index].Ppi)->PeiCoreFvLocation != 0)
>           ) {
> @@ -261,7 +260,8 @@ SecStartupPhase2(
>            CpuDeadLoop ();
>          }
>        }
> -    }
> +      Index++;
> +    } while ((PpiList[Index].Flags & EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST) != EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST);

Index is firstly increased, and comparison of the Flags is after that.
What if there is only one PPI in the list, the comparison happens in the random data out of the PPI list.

Thanks,
Ray