From f64a597d45f9a10c378735baeeaed0c0c42da527 Mon Sep 17 00:00:00 2001 From: Ray Ni Date: Mon, 26 Aug 2019 06:27:13 +0800 Subject: [PATCH] UefiCpuPkg: Explain relationship between several SMM PCDs There are three PCDs that may impact the behavior of each other in SMM environment: PcdCpuSmmProfileEnable PcdHeapGuardPropertyMask in MdeModulePkg PcdCpuSmmRestrictedMemoryAccess The patch updates the comments in DEC file to document it. Signed-off-by: Ray Ni Reviewed-by: Eric Dong Cc: Jiewen Yao Reviewed-by: Laszlo Ersek --- UefiCpuPkg/UefiCpuPkg.dec | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec index 83acd33612..9a03bdd716 100644 --- a/UefiCpuPkg/UefiCpuPkg.dec +++ b/UefiCpuPkg/UefiCpuPkg.dec @@ -81,7 +81,8 @@ [PcdsFeatureFlag] ## Indicates if SMM Profile will be enabled. # If enabled, instruction executions in and data accesses to memory outside of SMRAM will be logged. - # It could not be enabled at the same time with SMM static page table feature (PcdCpuSmmStaticPageTable). + # In X64 build, it could not be enabled when PcdCpuSmmRestrictedMemoryAccess is TRUE. + # In IA32 build, the page table memory is not marked as read-only when it is enabled. # This PCD is only for validation purpose. It should be set to false in production.

# TRUE - SMM Profile will be enabled.
# FALSE - SMM Profile will be disabled.
@@ -285,6 +286,11 @@ # The PCD value is considered as constantly TRUE in IA32 platforms. # When the PCD value is TRUE, page table is initialized to cover all memory spaces # and the memory occupied by page table is protected by page table itself as read-only. + # In X64 build, it cannot be enabled at the same time with SMM profile feature (PcdCpuSmmProfileEnable). + # In X64 build, it could not be enabled also at the same time with heap guard feature for SMM + # (PcdHeapGuardPropertyMask in MdeModulePkg). + # In IA32 build, page table memory is not marked as read-only when either SMM profile feature (PcdCpuSmmProfileEnable) + # or heap guard feature for SMM (PcdHeapGuardPropertyMask in MdeModulePkg) is enabled. # TRUE - Access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock.
# FALSE - Access to any type of non-SMRAM memory after SmmReadyToLock is allowed.
# @Prompt Access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock. -- 2.39.2