Re: [PATCH v7 2/9] x86/startup_64: Defer assignment of 5-level paging global variables

[Borislav Petkov]

On Fri, Mar 01, 2024 at 11:01:33AM +0100, Ard Biesheuvel wrote:
> The scenario that I have not managed to test is entering from EFI with
> 5 levels of paging enabled, and switching back to 4 levels (which
> should work regardless of CONFIG_X86_5LEVEL). However, no firmware in
> existence actually supports that today, and I am pretty sure that this
> code has never been tested under those conditions to begin with. (OVMF
> patches are under review atm to allow 5-level paging to be enabled in
> the firmware)

Aha.

> I currently don't have access to real hardware with LA57 support so
> any additional coverage there is highly appreciated (same for the last
> patch in this series)

Right, I'm sure dhansen could dig up such a machine. We'll ask him
nicely to test when the set is ready.

Thx.

-- 
Regards/Gruss,
    Boris.

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