UefiCpuPkg: Always Initialize Separate AP Exception Stacks

Today, CpuMpPei and CpuDxe only initialize separate exception
stacks for the APs when PcdCpuStackGuard is enabled so that
if a stack overflow occurs, hitting the guard page, the exception
can be handler with a separate stack.

However, this operation also creates a separate GDT for each AP.
This is a safer option than all APs sharing the BSP's GDT because
there are issues with concurrent access to the structures contained
within. Furthermore, even when a stack guard page is not present,
stack overflows can still occur and corrupt the stack; if an
exception is taken here, it is still valuable to have a separate
exception stack for sanity.

This commit updates CpuMpPei and CpuDxe to always create separate
exception stacks for the APs (and therefore separate GDTs).

Signed-off-by: Oliver Smith-Denny <osde@microsoft.com>

0 files changed, 0 insertions, 0 deletions