Re: [edk2-devel] [PATCH v2 04/14] OvmfPkg: provide a generic implementation of QemuLoadImageLib

["Laszlo Ersek" <lersek@redhat.com>]

On 03/04/20 10:52, Ard Biesheuvel wrote:
> Implement QemuLoadImageLib, and make it load the image provided by the
> QEMU_EFI_LOADER_FS_MEDIA_GUID/kernel device path that we implemented
> in a preceding patch in a separate DXE driver, using only the standard
> LoadImage and StartImage boot services.
> 
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2566
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.c   | 278 ++++++++++++++++++++
>  OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.inf |  38 +++
>  2 files changed, 316 insertions(+)

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks,
Laszlo

> diff --git a/OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.c b/OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.c
> new file mode 100644
> index 000000000000..f5edb43cc0b9
> --- /dev/null
> +++ b/OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.c
> @@ -0,0 +1,278 @@
> +/**  @file
> +  Generic implementation of QemuLoadImageLib library class interface.
> +
> +  Copyright (c) 2020, ARM Ltd. All rights reserved.<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +**/
> +
> +#include <Uefi.h>
> +
> +#include <Base.h>
> +#include <Guid/QemuKernelLoaderFsMedia.h>
> +#include <Library/DebugLib.h>
> +#include <Library/MemoryAllocationLib.h>
> +#include <Library/PrintLib.h>
> +#include <Library/QemuFwCfgLib.h>
> +#include <Library/QemuLoadImageLib.h>
> +#include <Library/UefiBootServicesTableLib.h>
> +#include <Protocol/DevicePath.h>
> +#include <Protocol/LoadedImage.h>
> +
> +#pragma pack (1)
> +typedef struct {
> +  EFI_DEVICE_PATH_PROTOCOL  FilePathHeader;
> +  CHAR16                    FilePath[ARRAY_SIZE (L"kernel")];
> +} KERNEL_FILE_DEVPATH;
> +
> +typedef struct {
> +  VENDOR_DEVICE_PATH        VenMediaNode;
> +  KERNEL_FILE_DEVPATH       FileNode;
> +  EFI_DEVICE_PATH_PROTOCOL  EndNode;
> +} KERNEL_VENMEDIA_FILE_DEVPATH;
> +#pragma pack ()
> +
> +STATIC CONST KERNEL_VENMEDIA_FILE_DEVPATH mKernelDevicePath = {
> +  {
> +    {
> +      MEDIA_DEVICE_PATH, MEDIA_VENDOR_DP,
> +      { sizeof (VENDOR_DEVICE_PATH) }
> +    },
> +    QEMU_KERNEL_LOADER_FS_MEDIA_GUID
> +  }, {
> +    {
> +      MEDIA_DEVICE_PATH, MEDIA_FILEPATH_DP,
> +      { sizeof (KERNEL_FILE_DEVPATH) }
> +    },
> +    L"kernel",
> +  }, {
> +    END_DEVICE_PATH_TYPE, END_ENTIRE_DEVICE_PATH_SUBTYPE,
> +    { sizeof (EFI_DEVICE_PATH_PROTOCOL) }
> +  }
> +};
> +
> +/**
> +  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
> +  @param[out] LoadedImage       The loaded image protocol that was installed
> +                                on ImageHandle by the LoadImage boot service.
> +
> +  @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
> +  )
> +{
> +  EFI_STATUS                Status;
> +  EFI_HANDLE                KernelImageHandle;
> +  EFI_LOADED_IMAGE_PROTOCOL *KernelLoadedImage;
> +  UINTN                     CommandLineSize;
> +  CHAR8                     *CommandLine;
> +  UINTN                     InitrdSize;
> +
> +  //
> +  // Load the image. This should call back into the QEMU EFI loader file system.
> +  //
> +  Status = gBS->LoadImage (
> +                  FALSE,                    // BootPolicy: exact match required
> +                  gImageHandle,             // ParentImageHandle
> +                  (EFI_DEVICE_PATH_PROTOCOL *)&mKernelDevicePath,
> +                  NULL,                     // SourceBuffer
> +                  0,                        // SourceSize
> +                  &KernelImageHandle
> +                  );
> +  switch (Status) {
> +  case EFI_SUCCESS:
> +    break;
> +
> +  case EFI_SECURITY_VIOLATION:
> +    //
> +    // In this case, the image was loaded but failed to authenticate.
> +    //
> +    Status = EFI_ACCESS_DENIED;
> +    goto UnloadImage;
> +
> +  default:
> +    DEBUG ((DEBUG_ERROR, "%a: LoadImage(): %r\n", __FUNCTION__, Status));
> +    return Status;
> +  }
> +
> +  //
> +  // Construct the kernel command line.
> +  //
> +  Status = gBS->OpenProtocol (
> +                  KernelImageHandle,
> +                  &gEfiLoadedImageProtocolGuid,
> +                  (VOID **)&KernelLoadedImage,
> +                  gImageHandle,                  // AgentHandle
> +                  NULL,                          // ControllerHandle
> +                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
> +                  );
> +  ASSERT_EFI_ERROR (Status);
> +
> +  QemuFwCfgSelectItem (QemuFwCfgItemCommandLineSize);
> +  CommandLineSize = (UINTN)QemuFwCfgRead32 ();
> +
> +  if (CommandLineSize == 0) {
> +    KernelLoadedImage->LoadOptionsSize = 0;
> +  } else {
> +    CommandLine = AllocatePool (CommandLineSize);
> +    if (CommandLine == NULL) {
> +      Status = EFI_OUT_OF_RESOURCES;
> +      goto UnloadImage;
> +    }
> +
> +    QemuFwCfgSelectItem (QemuFwCfgItemCommandLineData);
> +    QemuFwCfgReadBytes (CommandLineSize, CommandLine);
> +
> +    //
> +    // Verify NUL-termination of the command line.
> +    //
> +    if (CommandLine[CommandLineSize - 1] != '\0') {
> +      DEBUG ((DEBUG_ERROR, "%a: kernel command line is not NUL-terminated\n",
> +        __FUNCTION__));
> +      Status = EFI_PROTOCOL_ERROR;
> +      goto FreeCommandLine;
> +    }
> +
> +    //
> +    // Drop the terminating NUL, convert to UTF-16.
> +    //
> +    KernelLoadedImage->LoadOptionsSize = (CommandLineSize - 1) * 2;
> +  }
> +
> +  QemuFwCfgSelectItem (QemuFwCfgItemInitrdSize);
> +  InitrdSize = (UINTN)QemuFwCfgRead32 ();
> +
> +  if (InitrdSize > 0) {
> +    //
> +    // Append ' initrd=initrd' in UTF-16.
> +    //
> +    KernelLoadedImage->LoadOptionsSize += sizeof (L" initrd=initrd") - 2;
> +  }
> +
> +  if (KernelLoadedImage->LoadOptionsSize == 0) {
> +    KernelLoadedImage->LoadOptions = NULL;
> +  } else {
> +    //
> +    // NUL-terminate in UTF-16.
> +    //
> +    KernelLoadedImage->LoadOptionsSize += 2;
> +
> +    KernelLoadedImage->LoadOptions = AllocatePool (
> +                                       KernelLoadedImage->LoadOptionsSize);
> +    if (KernelLoadedImage->LoadOptions == NULL) {
> +      KernelLoadedImage->LoadOptionsSize = 0;
> +      Status = EFI_OUT_OF_RESOURCES;
> +      goto FreeCommandLine;
> +    }
> +
> +    UnicodeSPrintAsciiFormat (
> +      KernelLoadedImage->LoadOptions,
> +      KernelLoadedImage->LoadOptionsSize,
> +      "%a%a",
> +      (CommandLineSize == 0) ?  "" : CommandLine,
> +      (InitrdSize == 0)      ?  "" : " initrd=initrd"
> +      );
> +    DEBUG ((DEBUG_INFO, "%a: command line: \"%s\"\n", __FUNCTION__,
> +      (CHAR16 *)KernelLoadedImage->LoadOptions));
> +  }
> +
> +  *ImageHandle = KernelImageHandle;
> +  return EFI_SUCCESS;
> +
> +FreeCommandLine:
> +  if (CommandLineSize > 0) {
> +    FreePool (CommandLine);
> +  }
> +UnloadImage:
> +  gBS->UnloadImage (KernelImageHandle);
> +
> +  return Status;
> +}
> +
> +/**
> +  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
> +**/
> +EFI_STATUS
> +EFIAPI
> +QemuStartKernelImage (
> +  IN  OUT EFI_HANDLE          *ImageHandle
> +  )
> +{
> +  return gBS->StartImage (
> +                *ImageHandle,
> +                NULL,              // ExitDataSize
> +                NULL               // ExitData
> +                );
> +}
> +
> +/**
> +  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
> +  )
> +{
> +  EFI_LOADED_IMAGE_PROTOCOL   *KernelLoadedImage;
> +  EFI_STATUS                  Status;
> +
> +  Status = gBS->OpenProtocol (
> +                  ImageHandle,
> +                  &gEfiLoadedImageProtocolGuid,
> +                  (VOID **)&KernelLoadedImage,
> +                  gImageHandle,                  // AgentHandle
> +                  NULL,                          // ControllerHandle
> +                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
> +                  );
> +  if (EFI_ERROR (Status)) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  if (KernelLoadedImage->LoadOptions != NULL) {
> +    FreePool (KernelLoadedImage->LoadOptions);
> +    KernelLoadedImage->LoadOptions = NULL;
> +  }
> +  KernelLoadedImage->LoadOptionsSize = 0;
> +
> +  return gBS->UnloadImage (ImageHandle);
> +}
> diff --git a/OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.inf b/OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.inf
> new file mode 100644
> index 000000000000..b262cb926a4d
> --- /dev/null
> +++ b/OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.inf
> @@ -0,0 +1,38 @@
> +## @file
> +#  Generic implementation of QemuLoadImageLib library class interface.
> +#
> +#  Copyright (c) 2020, ARM Ltd. All rights reserved.<BR>
> +#
> +#  SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 1.27
> +  BASE_NAME                      = GenericQemuLoadImageLib
> +  FILE_GUID                      = 9e3e28da-c7b5-4f85-841a-84e6a9a1f1a0
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = QemuLoadImageLib|DXE_DRIVER
> +
> +[Sources]
> +  GenericQemuLoadImageLib.c
> +
> +[Packages]
> +  MdeModulePkg/MdeModulePkg.dec
> +  MdePkg/MdePkg.dec
> +  OvmfPkg/OvmfPkg.dec
> +
> +[LibraryClasses]
> +  DebugLib
> +  MemoryAllocationLib
> +  PrintLib
> +  QemuFwCfgLib
> +  UefiBootServicesTableLib
> +
> +[Protocols]
> +  gEfiDevicePathProtocolGuid
> +  gEfiLoadedImageProtocolGuid
> +
> +[Guids]
> +  gQemuKernelLoaderFsMediaGuid
>