[PATCH wave 1 01/10] OvmfPkg: introduce PcdQ35SmramAtDefaultSmbase

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

For supporting VCPU hotplug with SMM enabled/required, QEMU offers the
(dynamically detectable) feature called "SMRAM at default SMBASE". When
the feature is enabled, the firmware can lock down the 128 KB range
starting at the default SMBASE; that is, the [0x3_0000, 0x4_FFFF]
interval. The goal is to shield the very first SMI handler of the
hotplugged VCPU from OS influence.

Multiple modules in OVMF will have to inter-operate for locking down this
range. Introduce a dynamic PCD that will reflect the feature (to be
negotiated by PlatformPei), for coordination between drivers.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Joao M Martins <joao.m.martins@oracle.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Phillip Goerl <phillip.goerl@oracle.com>
Cc: Yingwen Chen <yingwen.chen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/OvmfPkg.dec        | 6 ++++++
 OvmfPkg/OvmfPkgIa32.dsc    | 1 +
 OvmfPkg/OvmfPkgIa32X64.dsc | 1 +
 OvmfPkg/OvmfPkgX64.dsc     | 1 +
 4 files changed, 9 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index d5fee805ef4a..57034c784f88 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -257,6 +257,12 @@ [PcdsDynamic, PcdsDynamicEx]
   #  This PCD is only accessed if PcdSmmSmramRequire is TRUE (see below).
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8|UINT16|0x20
 
+  ## Set to TRUE by PlatformPei if the Q35 board supports the "SMRAM at default
+  #  SMBASE" feature.
+  #
+  #  This PCD is only accessed if PcdSmmSmramRequire is TRUE (see below).
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase|FALSE|BOOLEAN|0x34
+
 [PcdsFeatureFlag]
   gUefiOvmfPkgTokenSpaceGuid.PcdQemuBootOrderPciTranslation|TRUE|BOOLEAN|0x1c
   gUefiOvmfPkgTokenSpaceGuid.PcdQemuBootOrderMmioTranslation|FALSE|BOOLEAN|0x1d
diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 66e944436a69..8a970a40cc62 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -561,6 +561,7 @@ [PcdsDynamicDefault]
 
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase|FALSE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x01
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
 !endif
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 51c2bfb44f14..2a3ba9ec2ca1 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -573,6 +573,7 @@ [PcdsDynamicDefault]
 
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase|FALSE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x01
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
 !endif
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index ba7a75884490..17a135a8edfe 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -572,6 +572,7 @@ [PcdsDynamicDefault]
 
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase|FALSE
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode|0x01
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
 !endif
-- 
2.19.1.3.g30247aa5d201