Re: [edk2-devel] [PATCH v2 06/11] ArmVirtPkg: Add kvmtool platform driver

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

On 05/14/20 11:29, Ard Biesheuvel wrote:
> On 5/14/20 10:40 AM, Sami Mujawar wrote:
>> Kvmtool is a virtual machine manager that enables
>> hosting KVM guests. It essentially provides an
>> emulated platform for guest operating systems.
>>
>> Kvmtool hands of a device tree containing the
>> current hardware configuration to the firmware.
>>
>> A standards-based operating system would use
>> ACPI to consume the platform hardware
>> information, while some operating systems may
>> prefer to use Device Tree.
>>
>> The KvmtoolPlatformDxe performs the platform
>> actions like determining if the firmware should
>> expose ACPI or the Device Tree based hardware
>> description to the operating system.
>>
>> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
>> ---
>>
>> Notes:
>>      v2:
>>        - Updated according to review comments.                     [Sami]
>>           v1:
>>        - Add kvmtool platform driver to support loading platform   [Sami]
>>          specific information.
>>        - Keep code to initialise the variable storage PCDs in the 
>> [Laszlo]
>>          platform-specific FVB driver.
>>        - Document code derived from                               
>> [Laszlo]
>>          "ArmVirtPkg/PlatformHasAcpiDtDxe"
>>          Ref: https://edk2.groups.io/g/devel/topic/30915278#30757
>>
>>   ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c   | 93
>> ++++++++++++++++++++
>>   ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf | 47 ++++++++++
>>   2 files changed, 140 insertions(+)
>>
>> diff --git a/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c
>> b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c
>> new file mode 100644
>> index
>> 0000000000000000000000000000000000000000..e7568f66f5ebeb0423fc1c10345cd8dad0800d94
>>
>> --- /dev/null
>> +++ b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c
>> @@ -0,0 +1,93 @@
>> +/** @file
>> +
>> +  The KvmtoolPlatformDxe performs the platform specific
>> initialization like:
>> +  - It decides if the firmware should expose ACPI or Device Tree-based
>> +    hardware description to the operating system.
>> +
>> +  Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.
>> +
>> +  SPDX-License-Identifier: BSD-2-Clause-Patent
>> +
>> +**/
>> +
>> +#include <Guid/VariableFormat.h>
>> +#include <Library/BaseLib.h>
>> +#include <Library/BaseMemoryLib.h>
>> +#include <Library/DebugLib.h>
>> +#include <Library/DxeServicesTableLib.h>
>> +#include <Library/UefiBootServicesTableLib.h>
>> +#include <Library/UefiDriverEntryPoint.h>
>> +#include <Protocol/FdtClient.h>
>> +
>> +/** Decide if the firmware should expose ACPI tables or Device Tree and
>> +    install the appropriate protocol interface.
>> +
>> +  Note: This function is derived from "ArmVirtPkg/PlatformHasAcpiDtDxe",
>> +        by dropping the word size check, and the fw_cfg check.
>> +
>> +  @param [in]  ImageHandle  Handle for this image.
>> +
>> +  @retval EFI_SUCCESS             Success.
>> +  @retval EFI_OUT_OF_RESOURCES    There was not enough memory to
>> install the
>> +                                  protocols.
>> +  @retval EFI_INVALID_PARAMETER   A parameter is invalid.
>> +
>> +**/
>> +STATIC
>> +EFI_STATUS
>> +PlatformHasAcpiDt (
>> +  IN EFI_HANDLE           ImageHandle
>> +  )
>> +{
>> +  if (!PcdGetBool (PcdForceNoAcpi)) {
>> +    // Expose ACPI tables
>> +    return gBS->InstallProtocolInterface (
>> +                  &ImageHandle,
>> +                  &gEdkiiPlatformHasAcpiGuid,
>> +                  EFI_NATIVE_INTERFACE,
>> +                  NULL
>> +                  );
>> +  }
>> +
>> +  // Expose the Device Tree.
>> +  return gBS->InstallProtocolInterface (
>> +                &ImageHandle,
>> +                &gEdkiiPlatformHasDeviceTreeGuid,
>> +                EFI_NATIVE_INTERFACE,
>> +                NULL
>> +                );
>> +}
>> +
>> +/** Entry point for Kvmtool Platform Dxe
>> +
>> +  @param [in]  ImageHandle  Handle for this image.
>> +  @param [in]  SystemTable  Pointer to the EFI system table.
>> +
>> +  @retval EFI_SUCCESS             Success.
>> +  @retval EFI_OUT_OF_RESOURCES    There was not enough memory to
>> install the
>> +                                  protocols.
>> +  @retval EFI_INVALID_PARAMETER   A parameter is invalid.
>> +
>> +**/
>> +EFI_STATUS
>> +EFIAPI
>> +KvmtoolPlatformDxeEntryPoint (
>> +  IN EFI_HANDLE           ImageHandle,
>> +  IN EFI_SYSTEM_TABLE     *SystemTable
>> +  )
>> +{
>> +  EFI_STATUS                     Status;
>> +
>> +  Status = PlatformHasAcpiDt (ImageHandle);
>> +  if (EFI_ERROR (Status)) {
>> +    goto Failed;
>> +  }
>> +
>> +  return Status;
>> +
>> +Failed:
>> +  ASSERT_EFI_ERROR (Status);
>> +  CpuDeadLoop ();
>> +
>> +  return Status;
>> +}
> 
> Please don't use CpuDeadLoop()s in your drivers.
> 
> Installing a protocol on an image handle like this should not ever fail,
> and if it does, it is unlikely to be an issue in the driver itself. So
> just use ASSERT_EFI_ERROR() here, and return EFI_SUCCESS.

I think Sami just followed the original code in
"ArmVirtPkg/PlatformHasAcpiDtDxe".

I'm fine either way:

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

Different question:

Should we ask Sami to become a designated reviewer (in Maintainers.txt)
for the kvmtool-specific modules under ArmVirtPkg? Personally I'm
unlikely to use kvmtool.

Thanks
Laszlo

> 
> 
>> diff --git a/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
>> b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
>> new file mode 100644
>> index
>> 0000000000000000000000000000000000000000..08a0fe5ce14469133479046385bdd48c22698639
>>
>> --- /dev/null
>> +++ b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
>> @@ -0,0 +1,47 @@
>> +#/** @file
>> +#
>> +#  The KvmtoolPlatformDxe performs the platform specific
>> initialization like:
>> +#  - It decides if the firmware should expose ACPI or Device Tree-based
>> +#    hardware description to the operating system.
>> +#
>> +#  Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.
>> +#
>> +#  SPDX-License-Identifier: BSD-2-Clause-Patent
>> +#
>> +#**/
>> +
>> +[Defines]
>> +  INF_VERSION                    = 0x0001001B
>> +  BASE_NAME                      = KvmtoolPlatformDxe
>> +  FILE_GUID                      = 7479CCCD-D721-442A-8C73-A72DBB886669
>> +  MODULE_TYPE                    = DXE_DRIVER
>> +  VERSION_STRING                 = 1.0
>> +  ENTRY_POINT                    = KvmtoolPlatformDxeEntryPoint
>> +
>> +[Sources]
>> +  KvmtoolPlatformDxe.c
>> +
>> +[Packages]
>> +  ArmVirtPkg/ArmVirtPkg.dec
>> +  EmbeddedPkg/EmbeddedPkg.dec
>> +  MdePkg/MdePkg.dec
>> +  MdeModulePkg/MdeModulePkg.dec
>> +
>> +[LibraryClasses]
>> +  BaseLib
>> +  BaseMemoryLib
>> +  DebugLib
>> +  DxeServicesTableLib
>> +  MemoryAllocationLib
>> +  UefiBootServicesTableLib
>> +  UefiDriverEntryPoint
>> +
>> +[Guids]
>> +  gEdkiiPlatformHasAcpiGuid       ## SOMETIMES_PRODUCES ## PROTOCOL
>> +  gEdkiiPlatformHasDeviceTreeGuid ## SOMETIMES_PRODUCES ## PROTOCOL
>> +
>> +[Pcd]
>> +  gArmVirtTokenSpaceGuid.PcdForceNoAcpi
>> +
>> +[Depex]
>> +  TRUE
>>
> 
> 
> 
>