DasharoPayloadPkg/BlSupportPei: fix PEI memory range discovery code

Previously, the code chose the highest non-reserved RAM region below
4G mark, regardless of its size. If the memory is fragmented, this
may result in failed memory allocation further down the line. Skip
regions smaller than PeiMemSize as defined in BlPeiEntryPoint.

This commit also fixes the MTRR setting that used the end of last
non-reserved RAM region. This may result in running out of available
MTRRs in some cases due to alignment. Now, the first MMIO region above
1M is used to determine where WB ends and UC begins.

Signed-off-by: Krystian Hebel <[email protected]>

DasharoPayloadPkg/BlSupportPei/BlSupportPei.c

@@ -8,6 +8,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 #include "BlSupportPei.h"
 
+#define PEI_MEM_SIZE                      SIZE_64MB
+
 #define LEGACY_8259_MASK_REGISTER_MASTER  0x21
 #define LEGACY_8259_MASK_REGISTER_SLAVE   0xA1
 
@@ -310,7 +312,6 @@ MemInfoCallback (
   EFI_PHYSICAL_ADDRESS    Base;
   EFI_RESOURCE_TYPE       Type;
   UINT64                  Size;
-  UINT32                  SystemLowMemTop;
   UINT8                   Flag;
 
   Attribute = EFI_RESOURCE_ATTRIBUTE_PRESENT |
@@ -327,12 +328,12 @@ MemInfoCallback (
   Size    = MemoryMapEntry->Size;
   Flag    = MemoryMapEntry->Flag;
 
-  if ((Base  < 0x100000) && ((Base + Size) > 0x100000)) {
-    Size -= (0x100000 - Base);
-    Base  = 0x100000;
+  if ((Base  < BASE_1MB) && ((Base + Size) > BASE_1MB)) {
+    Size -= (BASE_1MB - Base);
+    Base  = BASE_1MB;
   }
 
-  if (Base >= 0x100000) {
+  if (Base >= BASE_1MB) {
     if (!(Flag & EFI_RESOURCE_ATTRIBUTE_PRESENT)) {
       BuildResourceDescriptorHob (
         Type,
@@ -341,8 +342,14 @@ MemInfoCallback (
         Size
         );
     } else if (Type == EFI_RESOURCE_SYSTEM_MEMORY) {
-      if (Base < 0x100000000ULL) {
-        MemInfo->UsableLowMemTop = (UINT32)(Base + Size);
+      if (Base < BASE_4GB) {
+        //
+        // Skip regions smaller than PEI_MEM_SIZE, the highest non-reserved
+        // region may be too small.
+        //
+        if (Size >= PEI_MEM_SIZE) {
+          MemInfo->UsableLowMemTop = (UINT32)(Base + Size);
+        }
       } else {
         Attribute &= ~EFI_RESOURCE_ATTRIBUTE_TESTED;
       }
@@ -364,14 +371,16 @@ MemInfoCallback (
         Size,
         EfiACPIReclaimMemory
         );
-      if (Base < 0x100000000ULL) {
-        SystemLowMemTop = ((UINT32)(Base + Size) + 0x0FFFFFFF) & 0xF0000000;
-        if (SystemLowMemTop > MemInfo->SystemLowMemTop) {
-          MemInfo->SystemLowMemTop = SystemLowMemTop;
-        }
-      }
     } else if (Type == EFI_RESOURCE_MEMORY_MAPPED_IO) {
       BuildMemoryMappedIoRangeHob((EFI_PHYSICAL_ADDRESS)Base, Size);
+      //
+      // Find base of the lowest MMIO in range 1M - 4G.
+      //
+      if (Base < BASE_4GB) {
+        if (Base < MemInfo->SystemLowMemTop) {
+          MemInfo->SystemLowMemTop = Base;
+        }
+      }
     } else if (Type == EFI_RESOURCE_FIRMWARE_DEVICE) {
       BuildResourceDescriptorHob (
           EFI_RESOURCE_FIRMWARE_DEVICE,
@@ -513,7 +522,6 @@ BlPeiEntryPoint (
 {
   EFI_STATUS                       Status;
   UINT64                           LowMemorySize;
-  UINT64                           PeiMemSize = SIZE_64MB;
   EFI_PHYSICAL_ADDRESS             PeiMemBase = 0;
   UINT32                           RegEax;
   UINT8                            PhysicalAddressBits;
@@ -583,7 +591,8 @@ BlPeiEntryPoint (
   //
   // Parse memory info
   //
-  ZeroMem (&PldMemInfo, sizeof(PldMemInfo));
+  PldMemInfo.UsableLowMemTop = 0;
+  PldMemInfo.SystemLowMemTop = 0xFFFFFFFFUL;
   Status = ParseMemoryInfo (MemInfoCallback, &PldMemInfo);
   if (EFI_ERROR(Status)) {
     return Status;
@@ -593,18 +602,19 @@ BlPeiEntryPoint (
   // Install memory
   //
   LowMemorySize = PldMemInfo.UsableLowMemTop;
-  PeiMemBase = (LowMemorySize - PeiMemSize) & (~(BASE_64KB - 1));
-  DEBUG ((DEBUG_INFO, "Low memory 0x%lx\n", LowMemorySize));
+  ASSERT (LowMemorySize >= BASE_1MB + PEI_MEM_SIZE);
+  PeiMemBase = (LowMemorySize - PEI_MEM_SIZE) & (~(BASE_64KB - 1));
+  DEBUG ((DEBUG_INFO, "UsableLowMemTop 0x%lx\n", LowMemorySize));
   DEBUG ((DEBUG_INFO, "SystemLowMemTop 0x%x\n", PldMemInfo.SystemLowMemTop));
   DEBUG ((DEBUG_INFO, "PeiMemBase: 0x%lx.\n", PeiMemBase));
-  DEBUG ((DEBUG_INFO, "PeiMemSize: 0x%lx.\n", PeiMemSize));
-  Status = PeiServicesInstallPeiMemory (PeiMemBase, PeiMemSize);
+  DEBUG ((DEBUG_INFO, "PeiMemSize: 0x%lx.\n", PEI_MEM_SIZE));
+  Status = PeiServicesInstallPeiMemory (PeiMemBase, PEI_MEM_SIZE);
   ASSERT_EFI_ERROR (Status);
 
   //
   // Set cache on the physical memory
   //
-  MtrrSetMemoryAttribute (BASE_1MB, LowMemorySize - BASE_1MB, CacheWriteBack);
+  MtrrSetMemoryAttribute (BASE_1MB, PldMemInfo.SystemLowMemTop - BASE_1MB, CacheWriteBack);
   MtrrSetMemoryAttribute (0, 0xA0000, CacheWriteBack);
 
   //