OvmfPkg/ResetSystemLib: add driver for microvm

Uses the generic event device to reset and poweroff.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3599
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>

OvmfPkg/Library/ResetSystemLib/DxeResetSystemLibMicrovm.c

@@ -0,0 +1,49 @@
+/** @file
+  Reset System Library functions for OVMF
+
+  Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Base.h>                   // BIT1
+#include <PiDxe.h>
+
+#include <Library/BaseLib.h>        // CpuDeadLoop()
+#include <Library/DebugLib.h>       // ASSERT()
+#include <Library/DxeServicesTableLib.h>
+#include <Library/IoLib.h>          // IoWrite8()
+#include <Library/ResetSystemLib.h> // ResetCold()
+#include <Library/TimerLib.h>       // MicroSecondDelay()
+#include <Library/UefiRuntimeLib.h> // EfiGoneVirtual()
+#include <OvmfPlatforms.h>          // PIIX4_PMBA_VALUE
+
+EFI_STATUS
+EFIAPI
+DxeResetSystemLibMicrovmConstructor (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  UINTN                            Address = MICROVM_GED_MMIO_BASE;
+  EFI_STATUS                       Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR  Descriptor;
+
+  DEBUG ((DEBUG_INFO, "%a: start\n", __FUNCTION__));
+
+  Status = gDS->GetMemorySpaceDescriptor (Address, &Descriptor);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_INFO, "%a: GetMemorySpaceDescriptor failed\n", __FUNCTION__));
+    return RETURN_UNSUPPORTED;
+  }
+
+  Status = gDS->SetMemorySpaceAttributes (Address, SIZE_4KB,
+                                          Descriptor.Attributes | EFI_MEMORY_RUNTIME);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_INFO, "%a: SetMemorySpaceAttributes failed\n", __FUNCTION__));
+    return RETURN_UNSUPPORTED;
+  }
+
+  DEBUG ((DEBUG_INFO, "%a: done\n", __FUNCTION__));
+  return EFI_SUCCESS;
+}