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

[Verma, Vishal L]

On Thu, 2026-09-10 at 20:39 +0000, Edgecombe, Rick P wrote:
> On Thu, 2026-09-10 at 12:28 -0600, 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.
> 
> The logic and history makes sense to me. I'm surprised early printk is not
> useful this early.
> 
> Reviewed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
> 
> I see do_early_exception() -> handle_vc_boot_ghcb() has some early_printks().
> Presumably these don't work for the same reason?
> 
> 
Thanks for the review!

For handle_vc_boot_ghcb() - that's a #VC handler. #VE gets patched into
the idt_table via early_idts[], but #VC doesn't until later - in
trap_init(). So early #VCs still need to be handled here.