Re: [edk2-devel] [PATCH v4 7/7] OvmfPkg/LinuxInitrdDynamicShellCommand: bail if initrd already exists

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

On 03/03/20 15:01, Ard Biesheuvel wrote:
> Before taking any actions, check if an instance of the LoadFile2 exists
> already on the Linux initrd media GUID device path, and whether it was
> provided by this command. If so, abort, since no duplicate instances of
> the device path should exist.
> 
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2564
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c   | 31 ++++++++++++++++++++
>  OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni |  3 ++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
> index 47ed26b50d3a..ed8fbaa77069 100644
> --- a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
> +++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.c
> @@ -53,6 +53,33 @@ STATIC CONST SINGLE_NODE_VENDOR_MEDIA_DEVPATH mInitrdDevicePath = {
>    }
>  };
>  
> +STATIC
> +BOOLEAN
> +IsOtherInitrdDevicePathAlreadyInstalled (
> +  VOID
> +  )
> +{
> +  EFI_STATUS                  Status;
> +  EFI_DEVICE_PATH_PROTOCOL    *DevicePath;
> +  EFI_HANDLE                  Handle;
> +
> +  DevicePath = (EFI_DEVICE_PATH_PROTOCOL *)&mInitrdDevicePath;
> +  Status = gBS->LocateDevicePath (&gEfiLoadFile2ProtocolGuid, &DevicePath,
> +                  &Handle);
> +  if (EFI_ERROR (Status)) {
> +    return FALSE;
> +  }
> +
> +  //
> +  // Check whether the existing instance is one that we installed during
> +  // a previous invocation.
> +  //
> +  if (Handle == mInitrdLoadFile2Handle) {
> +    return FALSE;
> +  }
> +  return TRUE;
> +}

Looks good, the function will return TRUE when mInitrdLoadFile2Handle is
NULL.

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

Thanks
Laszlo


> +
>  STATIC
>  EFI_STATUS
>  EFIAPI
> @@ -217,6 +244,10 @@ RunInitrd (
>      } else {
>        ASSERT(FALSE);
>      }
> +  } else if (IsOtherInitrdDevicePathAlreadyInstalled ()) {
> +    ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_ALREADY_INSTALLED),
> +      mLinuxInitrdShellCommandHiiHandle, L"initrd");
> +    ShellStatus = SHELL_UNSUPPORTED;
>    } else {
>      if (ShellCommandLineGetCount (Package) > 2) {
>        ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_TOO_MANY),
> diff --git a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
> index a88fa6e3641b..4b6b1285fffd 100644
> --- a/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
> +++ b/OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.uni
> @@ -18,6 +18,7 @@
>  #langdef   en-US "english"
>  
>  #string STR_GEN_PROBLEM           #language en-US "%H%s%N: Unknown flag - '%H%s%N'\r\n"
> +#string STR_GEN_ALREADY_INSTALLED #language en-US "%H%s%N: Linux initrd already provided by platform\r\n"
>  #string STR_GEN_TOO_MANY          #language en-US "%H%s%N: Too many arguments.\r\n"
>  #string STR_GEN_TOO_FEW           #language en-US "%H%s%N: Too few arguments.\r\n"
>  #string STR_GEN_FIND_FAIL         #language en-US "%H%s%N: File not found - '%H%s%N'\r\n"
> @@ -47,3 +48,5 @@
>  "     Consumers of the LoadFile2 protocol on the LINUX_EFI_INITRD_MEDIA_GUID\r\n"
>  "     device path that are started via means other than the shell will be able\r\n"
>  "     to locate the protocol and invoke it.\r\n"
> +"  3. Exposing an initrd using this command is only supported if no initrd is\r\n"
> +"     already being exposed by another driver on the platform.\r\n"
>