OvmfPkg: introduce QemuLoadImageLib library class

Introduce the QemuLoadImageLib library class that we will instantiate
to load the kernel image passed via the QEMU command line using the
standard LoadImage boot service.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2566
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/Include/Library/QemuLoadImageLib.h

@@ -0,0 +1,84 @@
+/** @file
+  Load a kernel image and command line passed to QEMU via
+  the command line
+
+  Copyright (C) 2020, Arm, Limited.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef QEMU_LOAD_IMAGE_LIB_H__
+#define QEMU_LOAD_IMAGE_LIB_H__
+
+#include <Uefi/UefiBaseType.h>
+#include <Base.h>
+
+#include <Protocol/LoadedImage.h>
+
+/**
+  Download the kernel, the initial ramdisk, and the kernel command line from
+  QEMU's fw_cfg. The kernel will be instructed via its command line to load
+  the initrd from the same Simple FileSystem where the kernel was loaded from.
+
+  @param[out] ImageHandle       The image handle that was allocated for
+                                loading the image
+
+  @retval EFI_SUCCESS           The image was loaded successfully.
+  @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.
+  @retval EFI_ACCESS_DENIED     The underlying LoadImage boot service call
+                                returned EFI_SECURITY_VIOLATION, and the image
+                                was unloaded again.
+
+  @return                       Error codes from any of the underlying
+                                functions.
+**/
+EFI_STATUS
+EFIAPI
+QemuLoadKernelImage (
+  OUT EFI_HANDLE          *ImageHandle
+  );
+
+/**
+  Transfer control to a kernel image loaded with QemuLoadKernelImage ()
+
+  @param[in,out]  ImageHandle     Handle of image to be started. May assume a
+                                  different value on return if the image was
+                                  reloaded.
+
+  @retval EFI_INVALID_PARAMETER   ImageHandle is either an invalid image handle
+                                  or the image has already been initialized with
+                                  StartImage
+  @retval EFI_SECURITY_VIOLATION  The current platform policy specifies that the
+                                  image should not be started.
+
+  @return                         Error codes returned by the started image.
+                                  On success, the function doesn't return.
+**/
+EFI_STATUS
+EFIAPI
+QemuStartKernelImage (
+  IN  OUT EFI_HANDLE          *ImageHandle
+  );
+
+/**
+  Unloads an image loaded with QemuLoadKernelImage ().
+
+  @param  ImageHandle             Handle that identifies the image to be
+                                  unloaded.
+
+  @retval EFI_SUCCESS             The image has been unloaded.
+  @retval EFI_UNSUPPORTED         The image has been started, and does not
+                                  support unload.
+  @retval EFI_INVALID_PARAMETER   ImageHandle is not a valid image handle.
+
+  @return                         Exit code from the image's unload function.
+**/
+EFI_STATUS
+EFIAPI
+QemuUnloadKernelImage (
+  IN  EFI_HANDLE          ImageHandle
+  );
+
+#endif

OvmfPkg/OvmfPkg.dec

@@ -58,6 +58,11 @@
   #
   QemuBootOrderLib|Include/Library/QemuBootOrderLib.h
 
+  ##  @libraryclass  Load a kernel image and command line passed to QEMU via
+  #                  the command line
+  #
+  QemuLoadImageLib|Include/Library/QemuLoadImageLib.h
+
   ##  @libraryclass  Serialize (and deserialize) variables
   #
   SerializeVariablesLib|Include/Library/SerializeVariablesLib.h