Re: [PATCH] x86/tdx: Remove the early #VE handler

[Nikolay Borisov]

On 10.09.26 г. 21:28 ч., Vishal Verma wrote:
> tdx_early_handle_ve() emulates port I/O for #VEs taken before
> idt_setup_early_traps() installs the real #VE gate. Per commit
> 32e72854fa5f ("x86/tdx: Port I/O: Add early boot support"), it exists to
> support earlyprintk's serial driver.
>
> "earlyprintk=" and "earlycon=" are both early_param() handlers, so no
> console can be registered before parse_early_param(), which runs from
> setup_arch(), after idt_setup_early_traps() has replaced the early IDT.
> Nothing in the window between idt_setup_early_handler() and
> idt_setup_early_traps() does port I/O, so this emulation doesn't ever
> get called.
>
> Remove the handler. Any #VE in the early window now falls through to
> early_fixup_exception(), as it previously did for #VEs that were not I/O
> instructions.
>
> Found with the help of an LLM observing that the real IDT is installed
> before parse_early_param(). LLMs were also used to verify this. On a TDX
> guest booted with earlyprintk, a counter added to tdx_early_handle_ve()
> for testing remained 0 after boot.
>
> Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Cc: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>

Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>