[PATCH v2 10/11] OvmfPkg: introduce PcdCsmEnable feature flag

["Laszlo Ersek" <lersek@redhat.com>]

In the DXE phase and later, it is possible for a module to dynamically
determine whether a CSM is enabled. An example can be seen in commit
855743f71774 ("OvmfPkg: prevent 64-bit MMIO BAR degradation if there is no
CSM", 2016-05-25).

SEC and PEI phase modules cannot check the Legacy BIOS Protocol however.
For their sake, introduce a new feature PCD that simply reflects the
CSM_ENABLE build flag.

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien@xen.org>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---

Notes:
    v2:
    - new patch

 OvmfPkg/OvmfPkg.dec        | 5 +++++
 OvmfPkg/OvmfPkgIa32.dsc    | 3 +++
 OvmfPkg/OvmfPkgIa32X64.dsc | 3 +++
 OvmfPkg/OvmfPkgX64.dsc     | 3 +++
 OvmfPkg/OvmfXen.dsc        | 3 +++
 5 files changed, 17 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 57034c784f88..4c5b6511cb97 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -276,3 +276,8 @@ [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
+
+  ## Informs modules (including pre-DXE-phase modules) whether the platform
+  #  firmware contains a CSM (Compatibility Support Module).
+  #
+  gUefiOvmfPkgTokenSpaceGuid.PcdCsmEnable|FALSE|BOOLEAN|0x35
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 43ff51933609..19728f20b34e 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -428,6 +428,9 @@ [PcdsFeatureFlag]
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutGopSupport|TRUE
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutUgaSupport|FALSE
   gEfiMdeModulePkgTokenSpaceGuid.PcdInstallAcpiSdtProtocol|TRUE
+!ifdef $(CSM_ENABLE)
+  gUefiOvmfPkgTokenSpaceGuid.PcdCsmEnable|TRUE
+!endif
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 5b3e217e9220..3c0c229e3a72 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -433,6 +433,9 @@ [PcdsFeatureFlag]
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutGopSupport|TRUE
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutUgaSupport|FALSE
   gEfiMdeModulePkgTokenSpaceGuid.PcdInstallAcpiSdtProtocol|TRUE
+!ifdef $(CSM_ENABLE)
+  gUefiOvmfPkgTokenSpaceGuid.PcdCsmEnable|TRUE
+!endif
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index a378d0a449aa..f6c1d8d228c6 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -433,6 +433,9 @@ [PcdsFeatureFlag]
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutGopSupport|TRUE
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutUgaSupport|FALSE
   gEfiMdeModulePkgTokenSpaceGuid.PcdInstallAcpiSdtProtocol|TRUE
+!ifdef $(CSM_ENABLE)
+  gUefiOvmfPkgTokenSpaceGuid.PcdCsmEnable|TRUE
+!endif
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire|TRUE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmEnableBspElection|FALSE
diff --git a/OvmfPkg/OvmfXen.dsc b/OvmfPkg/OvmfXen.dsc
index 1b18f1769bbc..5751ff1f0352 100644
--- a/OvmfPkg/OvmfXen.dsc
+++ b/OvmfPkg/OvmfXen.dsc
@@ -361,6 +361,9 @@ [PcdsFeatureFlag]
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutGopSupport|TRUE
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutUgaSupport|FALSE
   gEfiMdeModulePkgTokenSpaceGuid.PcdInstallAcpiSdtProtocol|TRUE
+!ifdef $(CSM_ENABLE)
+  gUefiOvmfPkgTokenSpaceGuid.PcdCsmEnable|TRUE
+!endif
 
 [PcdsFixedAtBuild]
   gEfiMdeModulePkgTokenSpaceGuid.PcdStatusCodeMemorySize|1
-- 
2.19.1.3.g30247aa5d201