From: Mike Larkin <mlarkin@nested.page>
Subject: Re: SEV-ES guest: Only claim early GHCB pages when we actuall are SEV-ES guest
To: tech@openbsd.org
Date: Wed, 2 Jul 2025 11:47:12 -0700

On Tue, Jul 01, 2025 at 10:37:57AM +0200, Hans-Jörg Höxer wrote:
> Hi,
>
> as suggested by bluhm@, only claim GHCB pages when we are actually
> running SEV-ES guest mode.
>

I think this is overoptimization but ok mlarkin if this is the way
you want to head.

-ml

> Take care,
> HJ.
>
> ---
> commit d2444d09c945baad0e5d9283a50d466d7de7b400
> Author: Hans-Joerg Hoexer <hshoexer@genua.de>
> Date:   Mon Jun 30 15:29:35 2025 +0200
>
>     SEV-ES guest: Only claim early GHCB pages when we actuall are SEV-ES guest
>
> diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
> index 9b0badd610d..e0e8862d375 100644
> --- a/sys/arch/amd64/amd64/machdep.c
> +++ b/sys/arch/amd64/amd64/machdep.c
> @@ -1470,9 +1470,10 @@ init_x86_64(paddr_t first_avail)
>  	/*
>  	 * locore0 mapped 2 pages for use as GHCB before pmap is initialized.
>  	 */
> -	if (ISSET(cpu_sev_guestmode, SEV_STAT_ES_ENABLED))
> +	if (ISSET(cpu_sev_guestmode, SEV_STAT_ES_ENABLED)) {
>  		cpu_init_early_vctrap(first_avail);
> -	first_avail += 2 * NBPG;
> +		first_avail += 2 * NBPG;
> +	}
>
>  	/*
>  	 * locore0 mapped 3 pages for use before the pmap is initialized