From: Mike Larkin <mlarkin@nested.page>
Subject: Re: AMD SEV 2/5: ccp(4): provide ioctl for guestshutdown
To: Hans-Jörg Höxer <Hans-Joerg_Hoexer@genua.de>
Cc: tech@openbsd.org, dv@sisu.io, alexander.bluhm@gmx.net
Date: Thu, 29 Aug 2024 21:58:17 -0700

On Wed, Aug 28, 2024 at 05:52:58PM +0200, Hans-Jörg Höxer wrote:
> On Wed, Aug 28, 2024 at 03:24:18PM +0200, Hans-Jörg Höxer wrote:
> >
> > this diff provides a new ioctl for simplified guest shutdown.  Will be
> > used by vmd(8).
>
> diff updated wrt pledge_ioctl_psp().

ok mlarkin on this one

>
> --------------------------------------------------------------------------
> commit 35fbee6e7ab6f5a58502c51e800d149bbe8576af
> Author: Hans-Joerg Hoexer <hshoexer@genua.de>
> Date:   Tue Aug 13 17:36:21 2024 +0200
>
>     ccp(4): provide ioctl for guestshutdown
>
>     To shutdown a SEV-enabled guest, we have first to deactivate the
>     guest context in ccp(4), then decommission the guest context.  To
>     simplify guest shutdown combine these two operations in a single
>     ioctl.  As this ioctl does not directly map to a single ccp command
>     use a high number for this ioctl.  There will be more ioctls like
>     this one.
>
> diff --git a/sys/dev/ic/ccp.c b/sys/dev/ic/ccp.c
> index 17e96277c26..24f0680f03a 100644
> --- a/sys/dev/ic/ccp.c
> +++ b/sys/dev/ic/ccp.c
> @@ -564,6 +564,29 @@ psp_deactivate(struct psp_deactivate *udeact)
>  	return (0);
>  }
>
> +int
> +psp_guest_shutdown(struct psp_guest_shutdown *ugshutdown)
> +{
> +	struct psp_deactivate	deact;
> +	struct psp_decommission	decom;
> +	int			ret;
> +
> +	bzero(&deact, sizeof(deact));
> +	deact.handle = ugshutdown->handle;
> +	if ((ret = psp_deactivate(&deact)) != 0)
> +		return (ret);
> +
> +	if ((ret = psp_df_flush()) != 0)
> +		return (ret);
> +
> +	bzero(&decom, sizeof(decom));
> +	decom.handle = ugshutdown->handle;
> +	if ((ret = psp_decommission(&decom)) != 0)
> +		return (ret);
> +
> +	return (0);
> +}
> +
>  int
>  psp_snp_get_pstatus(struct psp_snp_platform_status *ustatus)
>  {
> @@ -642,6 +665,9 @@ pspioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p)
>  	case PSP_IOC_DEACTIVATE:
>  		ret = psp_deactivate((struct psp_deactivate *)data);
>  		break;
> +	case PSP_IOC_GUEST_SHUTDOWN:
> +		ret = psp_guest_shutdown((struct psp_guest_shutdown *)data);
> +		break;
>  	case PSP_IOC_SNP_GET_PSTATUS:
>  		ret =
>  		    psp_snp_get_pstatus((struct psp_snp_platform_status *)data);
> @@ -668,6 +694,7 @@ pledge_ioctl_psp(struct proc *p, long com)
>  	case PSP_IOC_LAUNCH_MEASURE:
>  	case PSP_IOC_LAUNCH_FINISH:
>  	case PSP_IOC_ACTIVATE:
> +	case PSP_IOC_GUEST_SHUTDOWN:
>  		return (0);
>  	default:
>  		return (pledge_fail(p, EPERM, PLEDGE_VMM));
> diff --git a/sys/dev/ic/ccpvar.h b/sys/dev/ic/ccpvar.h
> index e8e0514610d..9ccf96febf1 100644
> --- a/sys/dev/ic/ccpvar.h
> +++ b/sys/dev/ic/ccpvar.h
> @@ -243,6 +243,11 @@ struct psp_init {
>  } __packed;
>
>
> +struct psp_guest_shutdown {
> +	/* Input parameter for PSP_CMD_GUEST_SHUTDOWN */
> +	uint32_t		handle;
> +} __packed;
> +
>  /* Selection of PSP commands of the SEV-SNP ABI Version 1.55 */
>
>  #define PSP_CMD_SNP_PLATFORMSTATUS	0x81
> @@ -272,6 +277,7 @@ struct psp_snp_platform_status {
>  #define PSP_IOC_ACTIVATE	_IOW('P', 9, struct psp_activate)
>  #define PSP_IOC_DEACTIVATE	_IOW('P', 10, struct psp_deactivate)
>  #define PSP_IOC_SNP_GET_PSTATUS	_IOR('P', 11, struct psp_snp_platform_status)
> +#define PSP_IOC_GUEST_SHUTDOWN	_IOW('P', 255, struct psp_guest_shutdown)
>  #endif	/* __amd64__ */
>
>  #ifdef _KERNEL