Re: [kvm-unit-tests PATCH v1 0/3] x86 UEFI: pass envs and args

[Andrew Jones <drjones@redhat.com>]

On Sun, Feb 20, 2022 at 02:42:31PM -0800, Zixuan Wang wrote:
> Hello,
> 
> This patch series enables kvm-unit-tests to get envs and args under
> UEFI. The host passes envs and args through files:
> 
> 1. The host stores envs into ENVS.TXT and args into ARGS.TXT

EFI already has support for an environment and EFI apps can accept args.
Why not find a way to convert kvm-unit-tests ENV and unit tests args
into the EFI system and then use that?

efi_setup_argv()[*] in my original PoC does that. It uses gnu-efi, but
it should be easy to strip away the gnu-efi stuff and go straight for
the underlining EFI functions.

[*] https://github.com/rhdrjones/kvm-unit-tests/commit/12a49a2e97b457e23af10bb25cd972362b379951#:~:text=static%20void%20efi_setup_argv(EFI_HANDLE%20Image%2C%20EFI_SYSTEM_TABLE%20*SysTab)

If you want to mimic efi_setup_argv(), then you'll also need 85baf398
("lib/argv: Allow environ to be primed") from that same branch.

EFI wrapper scripts for each unit test can be generated to pass the args
to the unit test EFI apps automatically. For the environment, the EFI
vars can be set as usual for the system. For QEMU, that means creating
a VARS.fd and then adding another flash device to the VM to exposes it.

Thanks,
drew


> 2. The guest boots up and reads data from these files through UEFI file
> operation services
> 3. The file data is passed to corresponding setup functions
> 
> As a result, several x86 test cases (e.g., kvmclock_test and vmexit)
> can now get envs/args from the host [1], thus do not report FAIL when
> running ./run-tests.sh.
> 
> An alternative approach for envs/args passing under UEFI is to use
> QEMU's -append/-initrd options. However, this approach requires EFI
> binaries to be passed through QEMU's -kernel option. While currently,
> EFI binaries are loaded from a disk image. Changing this bootup process
> may make kvm-unit-tests (under UEFI) unable to run on bare-metal [2].
> On the other hand, passing envs/args through files should work on
> bare-metal because UEFI's file operation services do not rely on QEMU's
> functionalities, thus working on bare-metal.
> 
> The summary of this patch series:
> 
> Patch #1 pulls Linux kernel's UEFI definitions for file operations.
> 
> Patch #2 implements file read functions and envs setup functions.
> 
> Patch #3 implements the args setup functions.
> 
> Best regards,
> Zixuan
> 
> [1] https://github.com/TheNetAdmin/KVM-Unit-Tests-dev-fork/issues/8
> [2] https://lore.kernel.org/kvm/CAEDJ5ZQLm1rz+0a7MPPz3wMAoeTq2oH9z92sd0ZhCxEjWMkOpg@mail.gmail.com
> 
> Zixuan Wang (3):
>   x86 UEFI: pull UEFI definitions for file operations
>   x86 UEFI: read envs from file
>   x86 UEFI: read args from file
> 
>  lib/efi.c       | 150 ++++++++++++++++++++++++++++++++++++++++++++++++
>  lib/linux/efi.h |  82 +++++++++++++++++++++++++-
>  x86/efi/run     |  36 +++++++++++-
>  3 files changed, 265 insertions(+), 3 deletions(-)
> 
> -- 
> 2.35.1
>