[RFC PATCH v5 25/28] OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address

["Brijesh Singh" <brijesh.singh@amd.com>]

The SetMemoryEncDec() is used by the higher level routines to set or clear
the page encryption mask for system RAM and Mmio address. When SEV-SNP is
active, in addition to set/clear page mask it also updates the RMP table.
The RMP table updates are required for the system RAM address and not
the Mmio address.

Add a new parameter in SetMemoryEncDec() to tell whether the specified
address is Mmio. If its Mmio then skip the page state change in the RMP
table.

Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 .../X64/PeiDxeVirtualMemory.c                 | 20 ++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
index 56db1e4b6ecf..0bb86d768017 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
@@ -673,6 +673,7 @@ InternalMemEncryptSevCreateIdentityMap1G (
   @param[in]  Mode                    Set or Clear mode
   @param[in]  CacheFlush              Flush the caches before applying the
                                       encryption mask
+  @param[in]  Mmio                    The physical address specified is Mmio
 
   @retval RETURN_SUCCESS              The attributes were cleared for the
                                       memory region.
@@ -688,7 +689,8 @@ SetMemoryEncDec (
   IN    PHYSICAL_ADDRESS         PhysicalAddress,
   IN    UINTN                    Length,
   IN    MAP_RANGE_MODE           Mode,
-  IN    BOOLEAN                  CacheFlush
+  IN    BOOLEAN                  CacheFlush,
+  IN    BOOLEAN                  Mmio
   )
 {
   PAGE_MAP_AND_DIRECTORY_POINTER *PageMapLevel4Entry;
@@ -711,14 +713,15 @@ SetMemoryEncDec (
 
   DEBUG ((
     DEBUG_VERBOSE,
-    "%a:%a: Cr3Base=0x%Lx Physical=0x%Lx Length=0x%Lx Mode=%a CacheFlush=%u\n",
+    "%a:%a: Cr3Base=0x%Lx Physical=0x%Lx Length=0x%Lx Mode=%a CacheFlush=%u Mmio=%u\n",
     gEfiCallerBaseName,
     __FUNCTION__,
     Cr3BaseAddress,
     PhysicalAddress,
     (UINT64)Length,
     (Mode == SetCBit) ? "Encrypt" : "Decrypt",
-    (UINT32)CacheFlush
+    (UINT32)CacheFlush,
+    (UINT32)Mmio
     ));
 
   //
@@ -760,7 +763,7 @@ SetMemoryEncDec (
   //
   // The InternalSetPageState() is used for setting the page state in the RMP table.
   //
-  if ((Mode == ClearCBit) && MemEncryptSevSnpIsEnabled ()) {
+  if (!Mmio && (Mode == ClearCBit) && MemEncryptSevSnpIsEnabled ()) {
     InternalSetPageState (PhysicalAddress, EFI_SIZE_TO_PAGES (Length), SevSnpPageShared, FALSE);
   }
 
@@ -998,7 +1001,8 @@ InternalMemEncryptSevSetMemoryDecrypted (
            PhysicalAddress,
            Length,
            ClearCBit,
-           TRUE
+           TRUE,
+           FALSE
            );
 }
 
@@ -1031,7 +1035,8 @@ InternalMemEncryptSevSetMemoryEncrypted (
            PhysicalAddress,
            Length,
            SetCBit,
-           TRUE
+           TRUE,
+           FALSE
            );
 }
 
@@ -1064,6 +1069,7 @@ InternalMemEncryptSevClearMmioPageEncMask (
            PhysicalAddress,
            Length,
            ClearCBit,
-           FALSE
+           FALSE,
+           TRUE
            );
 }
-- 
2.17.1