Re: [PATCH] efi/x86: use naked RET on mixed mode call wrapper

[Linus Torvalds]

On Mon, Jul 18, 2022 at 9:28 AM Borislav Petkov <bp@xxxxxxx> wrote:
>
> So I'm being told we need to untrain on return from EFI to protect the
> kernel from it.

Why would we have to protect the kernel from EFI?

If we can't trust EFI, then the machine is already compromised. We
just *called* an EFI routine, if EFI is untrusted, it did something
random.

I mean, it could have already done something bad at boot time when it
loaded the kernel.

So no, let's not "protect ourselves from EFI".

             Linus