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

[Laszlo Ersek]

On 05/14/20 14:17, Ard Biesheuvel wrote:
> On 5/14/20 2:12 PM, Laszlo Ersek wrote:
>> 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 at 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 at 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.
>>
> 
> Not sure if you saw patch 11/11, but I agree that in general, but for
> ArmVirtPkg in particular as well, having package level maintainers is
> sufficient, and there is no need for maintainer roles beyond that.

OK -- If you think patch#11 is unnecessary, I won't insist; I'd just
like to avoid the expectation for me to deeply review or regression-test
kvmtool stuff.

Thanks
Laszlo


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