[PATCH v3 3/5] OvmfPkg: Define a new PPI GUID to signal TPM MMIO accessability

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

Define a new PPI GUID that is to be used as a signal of when it is safe
to access the TPM MMIO range. This is needed so that, when SEV is active,
the MMIO range can be mapped unencrypted before it is accessed.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 OvmfPkg/OvmfPkg.dec | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 9629707020ba..6ae733f6e39f 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -128,6 +128,10 @@ [Ppis]
   # has been discovered and recorded
   gOvmfTpmDiscoveredPpiGuid             = {0xb9a61ad0, 0x2802, 0x41f3, {0xb5, 0x13, 0x96, 0x51, 0xce, 0x6b, 0xd5, 0x75}}
 
+  # This PPI signals that accessing the MMIO range of the TPM is possible in
+  # the PEI phase, regardless of memory encryption
+  gOvmfTpmMmioAccessiblePpiGuid         = {0x35c84ff2, 0x7bfe, 0x453d, {0x84, 0x5f, 0x68, 0x3a, 0x49, 0x2c, 0xf7, 0xb7}}
+
 [Protocols]
   gVirtioDeviceProtocolGuid             = {0xfa920010, 0x6785, 0x4941, {0xb6, 0xec, 0x49, 0x8c, 0x57, 0x9f, 0x16, 0x0a}}
   gXenBusProtocolGuid                   = {0x3d3ca290, 0xb9a5, 0x11e3, {0xb7, 0x5d, 0xb8, 0xac, 0x6f, 0x7d, 0x65, 0xe6}}
-- 
2.31.0