[PATCH v2 1/8] OvmfPkg: introduce PcdMemVarstoreEmuEnable feature flag

[Laszlo Ersek <lersek@redhat.com>]

... and the corresponding MEM_VARSTORE_EMU_ENABLE build define, which
defaults to TRUE.

Setting the build flag to FALSE will later enable the exclusion of the
dynamically allocated, emulated, in-memory varstore.

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien.grall@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/OvmfPkg.dec        | 6 ++++++
 OvmfPkg/OvmfPkgIa32.dsc    | 4 ++++
 OvmfPkg/OvmfPkgIa32X64.dsc | 4 ++++
 OvmfPkg/OvmfPkgX64.dsc     | 4 ++++
 4 files changed, 18 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 27bcfc141e5a..f03dd7e27d6b 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -150,3 +150,9 @@ [PcdsFeatureFlag]
   #  runtime OS from tampering with firmware structures (special memory ranges
   #  used by OVMF, the varstore pflash chip, LockBox etc).
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|FALSE|BOOLEAN|0x1e
+
+  ## This feature flag reports whether in-memory (that is, non-flash) variable
+  #  emulation is enabled. Note that with PcdSmmSmramRequire set to TRUE, this
+  #  setting is irrelevant, as SMM/SMRAM support always requires flash
+  #  variables.
+  gUefiOvmfPkgTokenSpaceGuid.PcdMemVarstoreEmuEnable|TRUE|BOOLEAN|3
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 9d23f8c162e4..443da553d0a3 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -39,6 +39,7 @@ [Defines]
   DEFINE HTTP_BOOT_ENABLE        = FALSE
   DEFINE SMM_REQUIRE             = FALSE
   DEFINE TLS_ENABLE              = FALSE
+  DEFINE MEM_VARSTORE_EMU_ENABLE = TRUE
 
   #
   # Flash size selection. Setting FD_SIZE_IN_KB on the command line directly to
@@ -410,6 +411,9 @@ [PcdsFeatureFlag]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
 !endif
+!if $(MEM_VARSTORE_EMU_ENABLE) == FALSE
+  gUefiOvmfPkgTokenSpaceGuid.PcdMemVarstoreEmuEnable|FALSE
+!endif
 
 [PcdsFixedAtBuild]
   gEfiMdeModulePkgTokenSpaceGuid.PcdStatusCodeMemorySize|1
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index a9c667fed8b0..0fc81743bac4 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -39,6 +39,7 @@ [Defines]
   DEFINE HTTP_BOOT_ENABLE        = FALSE
   DEFINE SMM_REQUIRE             = FALSE
   DEFINE TLS_ENABLE              = FALSE
+  DEFINE MEM_VARSTORE_EMU_ENABLE = TRUE
 
   #
   # Flash size selection. Setting FD_SIZE_IN_KB on the command line directly to
@@ -415,6 +416,9 @@ [PcdsFeatureFlag]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
 !endif
+!if $(MEM_VARSTORE_EMU_ENABLE) == FALSE
+  gUefiOvmfPkgTokenSpaceGuid.PcdMemVarstoreEmuEnable|FALSE
+!endif
 
 [PcdsFixedAtBuild]
   gEfiMdeModulePkgTokenSpaceGuid.PcdStatusCodeMemorySize|1
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index abf570512a38..db33be4bc0b7 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -39,6 +39,7 @@ [Defines]
   DEFINE HTTP_BOOT_ENABLE        = FALSE
   DEFINE SMM_REQUIRE             = FALSE
   DEFINE TLS_ENABLE              = FALSE
+  DEFINE MEM_VARSTORE_EMU_ENABLE = TRUE
 
   #
   # Flash size selection. Setting FD_SIZE_IN_KB on the command line directly to
@@ -415,6 +416,9 @@ [PcdsFeatureFlag]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
 !endif
+!if $(MEM_VARSTORE_EMU_ENABLE) == FALSE
+  gUefiOvmfPkgTokenSpaceGuid.PcdMemVarstoreEmuEnable|FALSE
+!endif
 
 [PcdsFixedAtBuild]
   gEfiMdeModulePkgTokenSpaceGuid.PcdStatusCodeMemorySize|1
-- 
2.14.1.3.gb7cf6e02401b