From 17246cdfce3e920cff52dcc58acb9d2e1e7c5510 Mon Sep 17 00:00:00 2001
From: Alexander Graf <graf@amazon.com>
Date: Wed, 12 May 2021 09:58:13 +0200
Subject: [PATCH] Varstore: Use MMIO access for ARM

On ARM, we want to use MMIO instead of PIO to notify the hypervisor. Adapt
the code so that it uses MMIO on ARM.

Signed-off-by: Alexander Graf <graf@amazon.com>
Reviewed-by: Hendrik Borghorst <hborghor@amazon.de>
Reviewed-by: Lav Joshi <lavjoshi@amazon.de>
CC: Deepak Gupta <dkgupta@amazon.com>
CC: Alexander Graf <graf@amazon.com>
CC: David Woodhouse <dwmw@amazon.com>
CC: Hendrik Borghorst <hborghor@amazon.com>
CC: Saurav Sachidanand <sauravsc@amazon.com>

diff --git a/nitro/ExtVarStore/ExtVarStore.c b/nitro/ExtVarStore/ExtVarStore.c
index ade749c053..c2b0008c97 100644
--- a/nitro/ExtVarStore/ExtVarStore.c
+++ b/nitro/ExtVarStore/ExtVarStore.c
@@ -37,12 +37,27 @@
 #include "interface.h"
 
 static EFI_EVENT mExtVirtualAddressChangeEvent = NULL;
+#ifdef EXTVAR_MMIO_ADDRESS
+static UINTN mExtVarMMIO = EXTVAR_MMIO_ADDRESS;
+#endif
 
 static SPIN_LOCK var_lock;
 
 static VOID *comm_buf_phys;
 VOID *comm_buf;
 
+static void
+exec_command(VOID *buf)
+{
+  MemoryFence ();
+#ifdef EXTVAR_MMIO_ADDRESS
+  MmioWrite64 (mExtVarMMIO, ((UINTN)buf) >> 12);
+#else
+  IoWrite32 (EXTVAR_PORT_ADDRESS, ((UINTN)buf) >> 12);
+#endif
+  MemoryFence ();
+}
+
 STATIC
 EFI_STATUS
 EFIAPI
@@ -391,6 +406,9 @@ VariableClassAddressChangeEvent (
    * at runtime.
    */
   EfiConvertPointer (0x0, (VOID **) &comm_buf);
+#ifdef EXTVAR_MMIO_ADDRESS
+  EfiConvertPointer (0x0, (VOID **) &mExtVarMMIO);
+#endif
   ReleaseSpinLock(&var_lock);
 }
 
@@ -416,6 +434,20 @@ ExtVarStoreInit(IN EFI_HANDLE ImageHandle, IN EFI_SYSTEM_TABLE *SystemTable)
     return EFI_OUT_OF_RESOURCES;
   comm_buf = comm_buf_phys;
 
+#ifdef EXTVAR_MMIO_ADDRESS
+  Status = gDS->AddMemorySpace (
+      EfiGcdMemoryTypeMemoryMappedIo,
+      EXTVAR_MMIO_ADDRESS, EFI_PAGE_SIZE,
+      EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
+      );
+  ASSERT_EFI_ERROR (Status);
+
+  Status = gDS->SetMemorySpaceAttributes (
+      EXTVAR_MMIO_ADDRESS, EFI_PAGE_SIZE,
+      EFI_MEMORY_UC | EFI_MEMORY_RUNTIME);
+  ASSERT_EFI_ERROR (Status);
+#endif
+
   InitializeSpinLock(&var_lock);
 
   // Taken from FSVariable.c
diff --git a/nitro/ExtVarStore/ExtVarStore.inf b/nitro/ExtVarStore/ExtVarStore.inf
index 62930e0e1c..09c75ee5dd 100644
--- a/nitro/ExtVarStore/ExtVarStore.inf
+++ b/nitro/ExtVarStore/ExtVarStore.inf
@@ -37,6 +37,9 @@
   UefiDriverEntryPoint
   MemoryAllocationLib
   SynchronizationLib
+  IoLib
+
+[LibraryClasses.X64]
   PciLib
 
 [Guids]
diff --git a/nitro/ExtVarStore/interface.h b/nitro/ExtVarStore/interface.h
index 5225f07c9c..eee9ae5c65 100644
--- a/nitro/ExtVarStore/interface.h
+++ b/nitro/ExtVarStore/interface.h
@@ -17,7 +17,11 @@ enum command_t {
   COMMAND_ENTER_RUNTIME,
 };
 
-#define PORT_ADDRESS 0x0100
+#ifdef __aarch64__
+#define EXTVAR_MMIO_ADDRESS 0x09050000
+#else
+#define EXTVAR_PORT_ADDRESS 0x0100
+#endif
 #define SHMEM_PAGES  16
 
 #define VAR_STORE_VERSION 1
@@ -187,11 +191,3 @@ static inline EFI_STATUS unserialize_result(uefi_param_parser *parser, EFI_STATU
 {
 	return uefi_parser_pop_head(parser, status, sizeof(*status));
 }
-
-static inline void
-exec_command(VOID *buf)
-{
-  MemoryFence ();
-  IoWrite32 (PORT_ADDRESS, ((UINTN)buf) >> 12);
-  MemoryFence ();
-}