OvmfPkg/RiscVVirt: Add PlatformBootManagerLib library

RISC-V Qemu Virt platfform needs the PlatformBootManagerLib similar
to the one in ArmVirtPlatform. Add the library in OvmfPkg/RiscVVirt
leveraging the one from Arm.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Abner Chang <abner.chang@amd.com>
Reviewed-by: Andrei Warkentin <andrei.warkentin@intel.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>

OvmfPkg/RiscVVirt/Library/PlatformBootManagerLib/QemuKernel.c

@@ -0,0 +1,77 @@
+/** @file
+  Try to load an EFI-stubbed RISC-V Linux kernel from QEMU's fw_cfg.
+
+  This implementation differs from OvmfPkg/Library/LoadLinuxLib. An EFI
+  stub in the subject kernel is a hard requirement here.
+
+  Copyright (C) 2014-2016, Red Hat, Inc.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Library/QemuLoadImageLib.h>
+#include <Library/ReportStatusCodeLib.h>
+
+#include "PlatformBm.h"
+
+//
+// The entry point of the feature.
+//
+
+/**
+  Download the kernel, the initial ramdisk, and the kernel command line from
+  QEMU's fw_cfg. Construct a minimal SimpleFileSystem that contains the two
+  image files, and load and start the kernel from it.
+
+  The kernel will be instructed via its command line to load the initrd from
+  the same Simple FileSystem.
+
+  @retval EFI_NOT_FOUND         Kernel image was not found.
+  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.
+  @retval EFI_PROTOCOL_ERROR    Unterminated kernel command line.
+
+  @return                       Error codes from any of the underlying
+                                functions. On success, the function doesn't
+                                return.
+**/
+EFI_STATUS
+EFIAPI
+TryRunningQemuKernel (
+  VOID
+  )
+{
+  EFI_STATUS  Status;
+  EFI_HANDLE  KernelImageHandle;
+
+  Status = QemuLoadKernelImage (&KernelImageHandle);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  //
+  // Signal the EFI_EVENT_GROUP_READY_TO_BOOT event.
+  //
+  EfiSignalEventReadyToBoot ();
+
+  REPORT_STATUS_CODE (
+    EFI_PROGRESS_CODE,
+    (EFI_SOFTWARE_DXE_BS_DRIVER | EFI_SW_DXE_BS_PC_READY_TO_BOOT_EVENT)
+    );
+
+  //
+  // Start the image.
+  //
+  Status = QemuStartKernelImage (&KernelImageHandle);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((
+      DEBUG_ERROR,
+      "%a: QemuStartKernelImage(): %r\n",
+      __FUNCTION__,
+      Status
+      ));
+  }
+
+  QemuUnloadKernelImage (KernelImageHandle);
+
+  return Status;
+}