[edk2-platforms][PATCH 1/1] RPi4: reserve/map memory above 4GB when present

["Andrei Warkentin" <andrey.warkentin@gmail.com>]

This makes all 8GB usable on the Pi 4 8GB variant.

Like RAM in the 3-4GB range, this is still gated by the
option to limit RAM to 3GB.

Tested on 4GB and 8GB boards, with and without 3GB limit.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
---

 This is the v2 with Pete's feedback.

 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c        | 39 +++++---
 Platform/RaspberryPi/Library/PlatformLib/PlatformLib.inf  |  1 -
 Platform/RaspberryPi/Library/PlatformLib/RaspberryPiMem.c | 99 ++++++++++++--------
 Platform/RaspberryPi/RPi4/RPi4.dsc                        |  1 -
 Platform/RaspberryPi/RaspberryPi.dec                      |  1 -
 5 files changed, 88 insertions(+), 53 deletions(-)

diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
index 583f07c9..2ce3af89 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
@@ -343,7 +343,6 @@ ApplyVariables (
   UINT32 CpuClock = PcdGet32 (PcdCpuClock);
   UINT32 CustomCpuClock = PcdGet32 (PcdCustomCpuClock);
   UINT32 Rate = 0;
-  UINT64 SystemMemorySize;
 
   switch (CpuClock) {
   case CHIPSET_CPU_CLOCK_LOW:
@@ -386,27 +385,43 @@ ApplyVariables (
 
   if (mModelFamily >= 4 && PcdGet32 (PcdRamMoreThan3GB) != 0 &&
       PcdGet32 (PcdRamLimitTo3GB) == 0) {
+    UINT64 SystemMemorySize;
+    UINT64 SystemMemorySizeBelow4GB;
+
+    ASSERT (BCM2711_SOC_REGISTERS != 0);
+    SystemMemorySize = (UINT64)mModelInstalledMB * SIZE_1MB;
     /*
      * Similar to how we compute the > 3 GB RAM segment's size in PlatformLib/
      * RaspberryPiMem.c, with some overlap protection for the Bcm2xxx register
-     * spaces. This computation should also work for models with more than 4 GB
-     * RAM, if there ever exist ones.
+     * spaces. SystemMemorySizeBelow4GB tracks the maximum memory below 4GB
+     * line, factoring in the limit imposed by the SoC register range.
      */
-    SystemMemorySize = (UINT64)mModelInstalledMB * SIZE_1MB;
-    ASSERT (SystemMemorySize > 3UL * SIZE_1GB);
-    SystemMemorySize = MIN(SystemMemorySize, BCM2836_SOC_REGISTERS);
-    if (BCM2711_SOC_REGISTERS > 0) {
-      SystemMemorySize = MIN(SystemMemorySize, BCM2711_SOC_REGISTERS);
-    }
+    SystemMemorySizeBelow4GB = MIN(SystemMemorySize, 4UL * SIZE_1GB);
+    SystemMemorySizeBelow4GB = MIN(SystemMemorySizeBelow4GB, BCM2836_SOC_REGISTERS);
+    SystemMemorySizeBelow4GB = MIN(SystemMemorySizeBelow4GB, BCM2711_SOC_REGISTERS);
+
+    ASSERT (SystemMemorySizeBelow4GB > 3UL * SIZE_1GB);
 
     Status = gDS->AddMemorySpace (EfiGcdMemoryTypeSystemMemory, 3UL * BASE_1GB,
-                    SystemMemorySize - (3UL * SIZE_1GB),
+                    SystemMemorySizeBelow4GB - (3UL * SIZE_1GB),
                     EFI_MEMORY_UC | EFI_MEMORY_WC | EFI_MEMORY_WT | EFI_MEMORY_WB);
     ASSERT_EFI_ERROR (Status);
     Status = gDS->SetMemorySpaceAttributes (3UL * BASE_1GB,
-                    SystemMemorySize - (3UL * SIZE_1GB),
-                    EFI_MEMORY_WB);
+                    SystemMemorySizeBelow4GB - (3UL * SIZE_1GB), EFI_MEMORY_WB);
     ASSERT_EFI_ERROR (Status);
+
+    if (SystemMemorySize > 4UL * SIZE_1GB) {
+      //
+      // Register any memory above 4GB.
+      //
+      Status = gDS->AddMemorySpace (EfiGcdMemoryTypeSystemMemory, 4UL * BASE_1GB,
+                      SystemMemorySize - (4UL * SIZE_1GB),
+                      EFI_MEMORY_UC | EFI_MEMORY_WC | EFI_MEMORY_WT | EFI_MEMORY_WB);
+      ASSERT_EFI_ERROR (Status);
+      Status = gDS->SetMemorySpaceAttributes (4UL * BASE_1GB,
+                      SystemMemorySize - (4UL * SIZE_1GB), EFI_MEMORY_WB);
+      ASSERT_EFI_ERROR (Status);      
+    }
   }
 
   if (mModelFamily == 3 || mModelFamily == 2) {
diff --git a/Platform/RaspberryPi/Library/PlatformLib/PlatformLib.inf b/Platform/RaspberryPi/Library/PlatformLib/PlatformLib.inf
index f48016cc..54c3f303 100644
--- a/Platform/RaspberryPi/Library/PlatformLib/PlatformLib.inf
+++ b/Platform/RaspberryPi/Library/PlatformLib/PlatformLib.inf
@@ -55,7 +55,6 @@
   gEmbeddedTokenSpaceGuid.PcdDmaDeviceOffset
   gArmTokenSpaceGuid.PcdSystemMemoryBase
   gArmTokenSpaceGuid.PcdSystemMemorySize
-  gRaspberryPiTokenSpaceGuid.PcdExtendedMemoryBase
   gRaspberryPiTokenSpaceGuid.PcdNvStorageEventLogSize
   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageVariableSize
   gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingSize
diff --git a/Platform/RaspberryPi/Library/PlatformLib/RaspberryPiMem.c b/Platform/RaspberryPi/Library/PlatformLib/RaspberryPiMem.c
index aae189ec..60a7b43a 100644
--- a/Platform/RaspberryPi/Library/PlatformLib/RaspberryPiMem.c
+++ b/Platform/RaspberryPi/Library/PlatformLib/RaspberryPiMem.c
@@ -58,18 +58,55 @@ ArmPlatformGetVirtualMemoryMap (
 {
   UINTN                         Index = 0;
   UINTN                         GpuIndex;
-  INT64                         OrigMemorySize;
-  INT64                         SystemMemorySize;
+  INT64                         TotalMemorySize;
+  INT64                         MemorySizeBelow3GB;
+  INT64                         MemorySizeBelow4GB;
   ARM_MEMORY_REGION_DESCRIPTOR  *VirtualMemoryTable;
 
   // Early output of the info we got from VideoCore can prove valuable.
   DEBUG ((DEBUG_INFO, "Board Rev: 0x%lX\n", mBoardRevision));
-  DEBUG ((DEBUG_INFO, "Base RAM : 0x%ll08X (Size 0x%ll08X)\n", mSystemMemoryBase, mSystemMemoryEnd + 1));
+  DEBUG ((DEBUG_INFO, "RAM < 1GB: 0x%ll08X (Size 0x%ll08X)\n", mSystemMemoryBase, mSystemMemoryEnd + 1));
   DEBUG ((DEBUG_INFO, "VideoCore: 0x%ll08X (Size 0x%ll08X)\n", mVideoCoreBase, mVideoCoreSize));
 
   ASSERT (mSystemMemoryBase == 0);
   ASSERT (VirtualMemoryMap != NULL);
 
+  // Compute the total RAM size available on this platform
+  TotalMemorySize = SIZE_256MB;
+  TotalMemorySize <<= (mBoardRevision >> 20) & 0x07;
+  DEBUG ((DEBUG_INFO, "Total RAM: 0x%ll08X\n", TotalMemorySize));
+
+  //
+  // Ensure that what we declare as System Memory doesn't overlap with the
+  // SoC MMIO registers. This can be achieved through a MIN () with the
+  // base address since SystemMemoryBase is 0 (we assert if it isn't).
+  //
+  ASSERT (BCM2836_SOC_REGISTERS < 4UL * SIZE_1GB);
+  MemorySizeBelow4GB = MIN(TotalMemorySize, 4UL * SIZE_1GB);
+  MemorySizeBelow4GB = MIN(MemorySizeBelow4GB, BCM2836_SOC_REGISTERS);
+  if (BCM2711_SOC_REGISTERS > 0) {
+    ASSERT (BCM2836_SOC_REGISTERS < 4UL * SIZE_1GB);
+    MemorySizeBelow4GB = MIN(MemorySizeBelow4GB, BCM2711_SOC_REGISTERS);
+  }
+
+  //
+  // By default we limit the memory to 3 GB to work around OS support for
+  // DMA bugs in the SoC, for OSes that don't support _DMA range descriptors.
+  // On boards with more RAM (4GB, 8GB), the extra memory is  added by ConfigDxe
+  // provided the configuration setting for 3GB limit is off.
+  //
+  MemorySizeBelow3GB = MIN(MemorySizeBelow4GB, 3UL * SIZE_1GB);
+
+  //
+  // On Pi 3 we've seen SoC registers may overlap the reported VideoCore range,
+  // so clamp that down as well.
+  //
+  if (mVideoCoreBase + mVideoCoreSize > BCM2836_SOC_REGISTERS) {
+    mVideoCoreSize = BCM2836_SOC_REGISTERS - mVideoCoreBase;
+    DEBUG ((DEBUG_WARN, "VideoCore range overlapped SoC MMIO, now 0x%ll08X (Size 0x%ll08X)\n",
+            mVideoCoreBase, mVideoCoreSize));
+  }
+
   VirtualMemoryTable = (ARM_MEMORY_REGION_DESCRIPTOR*)AllocatePages
                        (EFI_SIZE_TO_PAGES (sizeof (ARM_MEMORY_REGION_DESCRIPTOR) *
                        MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS));
@@ -77,7 +114,6 @@ ArmPlatformGetVirtualMemoryMap (
     return;
   }
 
-
   // Firmware Volume
   VirtualMemoryTable[Index].PhysicalBase    = FixedPcdGet64 (PcdFdBaseAddress);
   VirtualMemoryTable[Index].VirtualBase     = VirtualMemoryTable[Index].PhysicalBase;
@@ -123,7 +159,7 @@ ArmPlatformGetVirtualMemoryMap (
   VirtualMemoryTable[Index].Length          = mSystemMemoryEnd + 1 - FixedPcdGet64 (PcdSystemMemoryBase);
   VirtualMemoryTable[Index].Attributes      = ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK;
   VirtualMemoryInfo[Index].Type             = RPI_MEM_BASIC_REGION;
-  VirtualMemoryInfo[Index++].Name           = L"Base System RAM";
+  VirtualMemoryInfo[Index++].Name           = L"System RAM < 1GB";
 
   // GPU Reserved
   GpuIndex = Index;
@@ -134,21 +170,9 @@ ArmPlatformGetVirtualMemoryMap (
   VirtualMemoryInfo[Index].Type             = RPI_MEM_UNMAPPED_REGION;
   VirtualMemoryInfo[Index++].Name           = L"GPU Reserved";
 
-  // Compute the total RAM size available on this platform
-  SystemMemorySize = SIZE_256MB;
-  SystemMemorySize <<= (mBoardRevision >> 20) & 0x07;
-
-  //
-  // Ensure that what we declare as System Memory doesn't overlap with the
-  // Bcm2836 SoC registers. This can be achieved through a MIN () with the
-  // base address since SystemMemoryBase is 0 (we assert if it isn't).
-  //
-  SystemMemorySize = MIN(SystemMemorySize, BCM2836_SOC_REGISTERS);
 
   // Extended SoC registers (PCIe, genet, ...)
   if (BCM2711_SOC_REGISTERS > 0) {
-    // Same overlap protection as above for the Bcm2711 SoC registers
-    SystemMemorySize                        = MIN(SystemMemorySize, BCM2711_SOC_REGISTERS);
     VirtualMemoryTable[Index].PhysicalBase  = BCM2711_SOC_REGISTERS;
     VirtualMemoryTable[Index].VirtualBase   = VirtualMemoryTable[Index].PhysicalBase;
     VirtualMemoryTable[Index].Length        = BCM2711_SOC_REGISTER_LENGTH;
@@ -159,45 +183,44 @@ ArmPlatformGetVirtualMemoryMap (
 
   // Base SoC registers
   VirtualMemoryTable[Index].PhysicalBase    = BCM2836_SOC_REGISTERS;
-  // On the Pi 3 the SoC registers may overlap VideoCore => fix this
-  if (VirtualMemoryTable[GpuIndex].PhysicalBase + VirtualMemoryTable[GpuIndex].Length > VirtualMemoryTable[Index].PhysicalBase) {
-    VirtualMemoryTable[GpuIndex].Length = VirtualMemoryTable[Index].PhysicalBase - VirtualMemoryTable[GpuIndex].PhysicalBase;
-  }
   VirtualMemoryTable[Index].VirtualBase     = VirtualMemoryTable[Index].PhysicalBase;
   VirtualMemoryTable[Index].Length          = BCM2836_SOC_REGISTER_LENGTH;
   VirtualMemoryTable[Index].Attributes      = ARM_MEMORY_REGION_ATTRIBUTE_DEVICE;
   VirtualMemoryInfo[Index].Type             = RPI_MEM_UNMAPPED_REGION;
   VirtualMemoryInfo[Index++].Name           = L"SoC Reserved (283x)";
 
-  //
-  // By default we limit the memory to 3 GB to work around the DMA bugs in the SoC,
-  // for OSes that don't support _DMA range descriptors. On 4GB boards, it's runtime
-  // setting to boot with 4 GB, and the additional 1 GB is added by ConfigDxe.
-  //
-  OrigMemorySize = SystemMemorySize;
-  SystemMemorySize = MIN(SystemMemorySize, 3UL * SIZE_1GB);
 
-  // If we have RAM above the 1 GB mark, declare it
-  if (SystemMemorySize - SIZE_1GB > 0) {
-    VirtualMemoryTable[Index].PhysicalBase  = FixedPcdGet64 (PcdExtendedMemoryBase);
+  // Memory in the 1GB - 3GB range is always available.
+  if (MemorySizeBelow3GB > SIZE_1GB) {
+    VirtualMemoryTable[Index].PhysicalBase  = SIZE_1GB;
     VirtualMemoryTable[Index].VirtualBase   = VirtualMemoryTable[Index].PhysicalBase;
-    VirtualMemoryTable[Index].Length        = SystemMemorySize - SIZE_1GB;
+    VirtualMemoryTable[Index].Length        = MemorySizeBelow3GB - VirtualMemoryTable[Index].PhysicalBase;
     VirtualMemoryTable[Index].Attributes    = ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK;
     VirtualMemoryInfo[Index].Type           = RPI_MEM_BASIC_REGION;
-    VirtualMemoryInfo[Index++].Name         = L"Extended System RAM below 3 GB";
+    VirtualMemoryInfo[Index++].Name         = L"Extended System RAM < 3GB";
   }
 
   //
-  // If we have RAM above 3 GB mark, declare it so it's mapped, but
-  // don't add it to the memory map. This is done later by ConfigDxe if necessary.
+  // If we have RAM in the 3GB - 4GB range, declare it as mapped, but don't
+  // add it to the memory map. This is done later by ConfigDxe if necessary.
   //
-  if (OrigMemorySize > (3UL * SIZE_1GB)) {
+  if (MemorySizeBelow4GB > 3UL * SIZE_1GB) {
     VirtualMemoryTable[Index].PhysicalBase  = 3UL * SIZE_1GB;
     VirtualMemoryTable[Index].VirtualBase   = VirtualMemoryTable[Index].PhysicalBase;
-    VirtualMemoryTable[Index].Length        = OrigMemorySize - VirtualMemoryTable[Index].PhysicalBase;
+    VirtualMemoryTable[Index].Length        = MemorySizeBelow4GB - VirtualMemoryTable[Index].PhysicalBase;
+    VirtualMemoryTable[Index].Attributes    = ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK;
+    VirtualMemoryInfo[Index].Type           = RPI_MEM_UNMAPPED_REGION;
+    VirtualMemoryInfo[Index++].Name         = L"Extended System RAM < 4GB";
+  }
+
+  // Same treatment for the memory above 4GB.
+  if (TotalMemorySize > 4UL * SIZE_1GB) {
+    VirtualMemoryTable[Index].PhysicalBase  = 4UL * SIZE_1GB;
+    VirtualMemoryTable[Index].VirtualBase   = VirtualMemoryTable[Index].PhysicalBase;
+    VirtualMemoryTable[Index].Length        = TotalMemorySize - VirtualMemoryTable[Index].PhysicalBase;
     VirtualMemoryTable[Index].Attributes    = ARM_MEMORY_REGION_ATTRIBUTE_WRITE_BACK;
     VirtualMemoryInfo[Index].Type           = RPI_MEM_UNMAPPED_REGION;
-    VirtualMemoryInfo[Index++].Name         = L"Extended System RAM above 3 GB";
+    VirtualMemoryInfo[Index++].Name         = L"Extended System RAM >= 4GB";
   }
 
   // End of Table
diff --git a/Platform/RaspberryPi/RPi4/RPi4.dsc b/Platform/RaspberryPi/RPi4/RPi4.dsc
index cbff9d99..e055f13c 100644
--- a/Platform/RaspberryPi/RPi4/RPi4.dsc
+++ b/Platform/RaspberryPi/RPi4/RPi4.dsc
@@ -403,7 +403,6 @@
   #
   # Device specific addresses
   #
-  gRaspberryPiTokenSpaceGuid.PcdExtendedMemoryBase|0x40000000
   gBcm27xxTokenSpaceGuid.PcdBcm27xxRegistersAddress|0xfc000000
   gBcm27xxTokenSpaceGuid.PcdBcmGenetRegistersAddress|0xfd580000
   gBcm283xTokenSpaceGuid.PcdBcm283xRegistersAddress|0xfe000000
diff --git a/Platform/RaspberryPi/RaspberryPi.dec b/Platform/RaspberryPi/RaspberryPi.dec
index 1a3c44e0..5b402123 100644
--- a/Platform/RaspberryPi/RaspberryPi.dec
+++ b/Platform/RaspberryPi/RaspberryPi.dec
@@ -39,7 +39,6 @@
   gRaspberryPiTokenSpaceGuid.PcdNvStorageVariableBase|0x0|UINT32|0x00000005
   gRaspberryPiTokenSpaceGuid.PcdNvStorageFtwSpareBase|0x0|UINT32|0x00000006
   gRaspberryPiTokenSpaceGuid.PcdNvStorageFtwWorkingBase|0x0|UINT32|0x00000007
-  gRaspberryPiTokenSpaceGuid.PcdExtendedMemoryBase|0x0|UINT32|0x00000008
   gRaspberryPiTokenSpaceGuid.PcdFdtSize|0x10000|UINT32|0x00000009
   gRaspberryPiTokenSpaceGuid.PcdCpuLowSpeedMHz|600|UINT32|0x0000000a
   gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz|800|UINT32|0x0000000b
-- 
2.17.1