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

[Edgecombe, Rick P]

On Fri, 2026-09-11 at 11:37 +0100, Kiryl Shutsemau wrote:
> > Reviewed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
> 
> Rick, could you actually test it?

I didn't test it myself, but discussed with Vishal his testing.

> 
> Are we sure there's no other port I/O in before idt_setup_early_traps()?

It was a concern that some other feature besides early printk might use port io.
But none were found. Andi's recollection was that he hit something that needed
this, but this may have been with some older changed early printk behavior.

> 
> I don't see anything direct, but exception path is different story.
> 
> native_machine_emergency_restart() does port I/O for BOOT_KBD which
> seems to be reachable and leads to #VE with the patch:
> 
> machine_emergency_restart()
>   __machine_emergency_restart(1)
>     machine_ops.emergency_restart()
>       native_machine_emergency_restart()
>         reboot_type == BOOT_ACPI (default)
> 	acpi_reboot()
> 	reboot_type = BOOT_KBD
>   	  kb_wait()
>             inb(0x64) --> #VE

Is BOOT_KBD something that you think could be hit from a TDX guest?

> 
> Could you check if the patch changes panic() behaviour in the window
> before idt_setup_early_traps()?

Can you describe more what you are imagining? panic() doing early printk or some
other port io? Wondering if you have some more specific hunch.