OvmfPkg: Define a new PPI GUID to signal TPM MMIO accessability

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>
Message-Id: <03e292339273721724c8b14605cfe9d7bbe45a71.1619716333.git.thomas.lendacky@amd.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 9629707020ba9e31a8774e079bb02939d78cd190..6ae733f6e39f449db2d95644b3f52332fb6dba61 100644 (file)
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -128,6 +128,10 @@
   # has been discovered and recorded\r
   gOvmfTpmDiscoveredPpiGuid             = {0xb9a61ad0, 0x2802, 0x41f3, {0xb5, 0x13, 0x96, 0x51, 0xce, 0x6b, 0xd5, 0x75}}\r
 \r
+  # This PPI signals that accessing the MMIO range of the TPM is possible in\r
+  # the PEI phase, regardless of memory encryption\r
+  gOvmfTpmMmioAccessiblePpiGuid         = {0x35c84ff2, 0x7bfe, 0x453d, {0x84, 0x5f, 0x68, 0x3a, 0x49, 0x2c, 0xf7, 0xb7}}\r
+\r
 [Protocols]\r
   gVirtioDeviceProtocolGuid             = {0xfa920010, 0x6785, 0x4941, {0xb6, 0xec, 0x49, 0x8c, 0x57, 0x9f, 0x16, 0x0a}}\r
   gXenBusProtocolGuid                   = {0x3d3ca290, 0xb9a5, 0x11e3, {0xb7, 0x5d, 0xb8, 0xac, 0x6f, 0x7d, 0x65, 0xe6}}\r