ArmVirtPkg: Map QEMU fw_cfg MMIO region in PEI

Get the QEMU fw_cfg MMIO range from the device tree and add it
to the PEI virtual memory map. This ensures the fw_cfg selector
and data registers are mapped as device memory before
PlatformPei initialises the PEIM instance of QemuFwCfgLib.

Without this mapping, accessing the fw_cfg selector can trigger a
synchronous exception during PEI on ArmVirtQemu.

Note: The PlatformPeiLib calls QemuFwCfgGetAsString() to read
the "opt/org.tianocore/DebugLevel", which results in the
QemuFwCfgMmioPeiLib constructor QemuFwCfgInitialize() being
invoked that accesses the fw_cfg MMIO range.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>

1 files changed, 95 insertions, 1 deletions

diff --git a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c
index e0a1182041..7c6d84db65 100644
--- a/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c
+++ b/ArmVirtPkg/Library/QemuVirtMemInfoLib/QemuVirtMemInfoLib.c
@@ -10,14 +10,16 @@
 #include <Uefi.h>

 #include <Pi/PiMultiPhase.h>

 #include <Library/ArmLib.h>

+#include <Library/BaseLib.h>

 #include <Library/BaseMemoryLib.h>

 #include <Library/DebugLib.h>

 #include <Library/HobLib.h>

 #include <Library/MemoryAllocationLib.h>

 #include <Library/FdtSerialPortAddressLib.h>

+#include <Library/FdtLib.h>

 

 // Number of Virtual Memory Map Descriptors

-#define MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS  (4)

+#define MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS  (5)

 

 /** A macro to trace the memory map.

 **/

@@ -100,6 +102,75 @@ GetUartBase (
 }

 

 /**

+  Get the QEMU fw_cfg MMIO region from the device tree.

+

+  @param[in]  DeviceTreeBase        Base address of the Device Tree.

+  @param[out] FwCfgBase             Base address of the fw_cfg MMIO region.

+  @param[out] FwCfgSize             Size of the fw_cfg MMIO region.

+

+  @retval RETURN_INVALID_PARAMETER  Device Tree Base address is invalid.

+  @retval RETURN_NOT_FOUND          No fw_cfg MMIO node has been found.

+  @retval RETURN_SUCCESS            FwCfgBase and FwCfgSize have been populated.

+**/

+STATIC

+RETURN_STATUS

+EFIAPI

+GetFwCfgMmioRegion (

+  IN  VOID    *DeviceTreeBase,

+  OUT UINT64  *FwCfgBase,

+  OUT UINT64  *FwCfgSize

+  )

+{

+  RETURN_STATUS  Status;

+  INT32          Len;

+  INT32          Node;

+  INT32          Prev;

+  CONST CHAR8    *Type;

+  CONST UINT64   *Reg;

+

+  if (DeviceTreeBase == NULL) {

+    return RETURN_INVALID_PARAMETER;

+  }

+

+  Status = RETURN_NOT_FOUND;

+  for (Prev = 0; ; Prev = Node) {

+    Node = FdtNextNode (DeviceTreeBase, Prev, NULL);

+    if (Node < 0) {

+      break;

+    }

+

+    //

+    // Check for memory node

+    //

+    Type = FdtGetProp (DeviceTreeBase, Node, "compatible", &Len);

+    if ((Type != NULL) &&

+        (AsciiStrnCmp (Type, "qemu,fw-cfg-mmio", Len) == 0))

+    {

+      //

+      // Get the 'reg' property of this node. For now, we will assume

+      // two 8 byte quantities for base and size, respectively.

+      //

+      Reg = FdtGetProp (DeviceTreeBase, Node, "reg", &Len);

+      if ((Reg != 0) && (Len == (2 * sizeof (UINT64)))) {

+        *FwCfgBase = SwapBytes64 (ReadUnaligned64 ((VOID *)&Reg[0]));

+        *FwCfgSize = SwapBytes64 (ReadUnaligned64 ((VOID *)&Reg[1]));

+        Status     = RETURN_SUCCESS;

+        break;

+      } else {

+        DEBUG ((

+          DEBUG_ERROR,

+          "%a: Failed to parse FDT QemuCfg node\n",

+          __func__

+          ));

+        break;

+      }

+    }

+  } // for

+

+  return Status;

+}

+

+/**

   Return the Virtual Memory Map of your platform

 

   This Virtual Memory Map is used by MemoryInitPei Module to initialize the MMU

@@ -125,6 +196,8 @@ ArmVirtGetMemoryMap (
   UINT64                        MappingBase;

   UINT64                        MappingSize;

   UINT64                        UartBase;

+  UINT64                        FwCfgBase;

+  UINT64                        FwCfgSize;

 

   ASSERT (VirtualMemoryMap != NULL);

 

@@ -148,6 +221,15 @@ ArmVirtGetMemoryMap (
     return;

   }

 

+  RetStatus = GetFwCfgMmioRegion (DeviceTreeBase, &FwCfgBase, &FwCfgSize);

+  if (RETURN_ERROR (RetStatus) ||

+      (FwCfgBase == 0) ||

+      (FwCfgSize == 0))

+  {

+    ASSERT_RETURN_ERROR (RetStatus);

+    return;

+  }

+

   VirtualMemoryTable = AllocatePool (

                          sizeof (ARM_MEMORY_REGION_DESCRIPTOR) *

                          MAX_VIRTUAL_MEMORY_MAP_DESCRIPTORS

@@ -192,6 +274,18 @@ ArmVirtGetMemoryMap (
   LOG_MEM_MAP ("Serial Port");

   Idx++;

 

+  // Map the fw_cfg MMIO region

+  MappingBase = FwCfgBase & ~(UINT64)EFI_PAGE_MASK;

+  MappingSize = EFI_PAGES_TO_SIZE (

+                  EFI_SIZE_TO_PAGES (FwCfgBase - MappingBase + FwCfgSize)

+                  );

+  VirtualMemoryTable[Idx].PhysicalBase = MappingBase;

+  VirtualMemoryTable[Idx].VirtualBase  = MappingBase;

+  VirtualMemoryTable[Idx].Length       = MappingSize;

+  VirtualMemoryTable[Idx].Attributes   = ARM_MEMORY_REGION_ATTRIBUTE_DEVICE;

+  LOG_MEM_MAP ("FwCfg");

+  Idx++;

+

   // End of Table

   ZeroMem (&VirtualMemoryTable[Idx], sizeof (ARM_MEMORY_REGION_DESCRIPTOR));