[PATCH v4 11/11] UefiCpuPkg/MpInitLib: For SEV-ES guest, set stack based on processor number

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

From: Tom Lendacky <thomas.lendacky@amd.com>

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3008

Set the SEV-ES reset stack address for an AP based on the processor number
instead of the APIC ID in case the APIC IDs are not zero-based and densely
packed/enumerated. This will ensure an AP reset stack address does not get
set outside of the AP reset stack memory allocation.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Acked-by: Ray Ni <ray.ni@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 1f47ff3f73b5..681fa79b4cff 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -680,11 +680,16 @@ MpInitLibSevEsAPReset (
   IN CPU_MP_DATA                  *CpuMpData
   )
 {
+  EFI_STATUS       Status;
+  UINTN            ProcessorNumber;
   UINT16           Code16, Code32;
   AP_RESET         *APResetFn;
   UINTN            BufferStart;
   UINTN            StackStart;
 
+  Status = GetProcessorNumber (CpuMpData, &ProcessorNumber);
+  ASSERT_EFI_ERROR (Status);
+
   Code16 = GetProtectedMode16CS ();
   Code32 = GetProtectedMode32CS ();
 
@@ -696,7 +701,7 @@ MpInitLibSevEsAPReset (
 
   BufferStart = CpuMpData->MpCpuExchangeInfo->BufferStart;
   StackStart = CpuMpData->SevEsAPResetStackStart -
-                 (AP_RESET_STACK_SIZE * GetApicId ());
+                 (AP_RESET_STACK_SIZE * ProcessorNumber);
 
   //
   // This call never returns.
-- 
2.28.0