Re: [PATCH] efi: Allocate runtime workqueue before ACPI init

On Tue, 19 May 2026, at 16:12, Rafael J. Wysocki wrote:
> On Tue, May 19, 2026 at 10:23 AM Ard Biesheuvel <[email protected]> wrote:
>>
>> From: Ard Biesheuvel <[email protected]>
>>
>> Since commit
>>
>>   5894cf571e14 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers")
>>
>> ACPI PRM calls are delegated to a workqueue which runs in a kernel
>> thread, making it easier to detect and mitigate faulting memory accesses
>> performed by the firmware.
>>
>> Rafael reports that such PRM accesses may occur before efisubsys_init()
>> executes, which is where the workqueue is allocated, leading to NULL
>> pointer dereferences. Since acpi_init() [which triggers the early PRM
>> accesses] executes as a subsys_initcall() as well, and has its own
>> dependencies that may be sensitive to initcall ordering, deferring
>> acpi_init() is not an option.
>>
>> So instead, split off the workqueue allocation into its own postcore
>> initcall, as this is the only missing piece to allow EFI runtime calls
>> to be made. This ensures that EFI runtime call (including PRM calls) are
>> accessible to all code running at subsys_initcall() level.
>>
>> Fixes: 5894cf571e14 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers")
>> Reported-by: "Rafael J. Wysocki" <[email protected]>
>> Signed-off-by: Ard Biesheuvel <[email protected]>
>
> This should work AFAICS, so
>
> Reviewed-by: Rafael J. Wysocki (Intel) <[email protected]>
>

OK, I'll queue this up.