Re: [PATCHv2 11/29] x86/boot: Allow to hook up alternative port I/O helpers

Borislav Petkov
2022-02-01T19:02:41Z

On Mon, Jan 24, 2022 at 06:01:57PM +0300, Kirill A. Shutemov wrote:
> Port I/O instructions trigger #VE in the TDX environment. In response to
> the exception, kernel emulates these instructions using hypercalls.
>
> But during early boot, on the decompression stage, it is cumbersome to
> deal with #VE. It is cleaner to go to hypercalls directly, bypassing #VE
> handling.
>
> Add a way to hook up alternative port I/O helpers in the boot stub.
> All port I/O operations are routed via 'pio_ops'. By default 'pio_ops'
> initialized with native port I/O implementations.

I see that you like to talk about what a patch is doing in the commit
message but there's really no need for it - that's visible from the diff
itself, hopefully.

So talk about the *why* instead, pls.

> This is a preparation patch. The next patch will override 'pio_ops' if
> the kernel booted in the TDX environment.

That's also not needed.

The rest LGTM.

--
Regards/Gruss,
Boris.