On Tue, Sep 09, 2025 at 11:42:38AM +0200, Hans-Jörg Höxer wrote:
> Hi,
>
> this is an updated diff that works well on vmd/vmm and linux/kvm hosts
> with SEV-ES enabled guests.
>
> The previous discussion raised some questions, thanks for your input!
> All in all we came to the conclusion to proceed with this approach.
>
> ok?
>

what was the final decision here?

-ml

> Take care,
> HJ.
> -------------------------------------------------------------------------
>
> commit 576036aa72fef155f1584690fab5bdfe018672b8
> Author: Hans-Joerg Hoexer <hshoexer@genua.de>
> Date:   Sat Aug 2 12:58:50 2025 +0200
>
>     Whitelist devices in cfdrive for use when SEV is enabled
>
>     Skip devices, that are not flagged for use with SEV.  Hook into
>     config_search() and isascan().
>
> diff --git a/sys/arch/amd64/amd64/bios.c b/sys/arch/amd64/amd64/bios.c
> index 3a264d09d5b..15dec870ba6 100644
> --- a/sys/arch/amd64/amd64/bios.c
> +++ b/sys/arch/amd64/amd64/bios.c
> @@ -50,7 +50,7 @@ const struct cfattach bios_ca = {
>  };
>
>  struct cfdriver bios_cd = {
> -	NULL, "bios", DV_DULL
> +	NULL, "bios", DV_DULL, CD_COCOVM
>  };
>
>  struct smbios_entry smbios_entry;
> diff --git a/sys/arch/amd64/amd64/cpu.c b/sys/arch/amd64/amd64/cpu.c
> index 1287c610344..b8ad479cefa 100644
> --- a/sys/arch/amd64/amd64/cpu.c
> +++ b/sys/arch/amd64/amd64/cpu.c
> @@ -445,7 +445,7 @@ const struct cfattach cpu_ca = {
>  };
>
>  struct cfdriver cpu_cd = {
> -	NULL, "cpu", DV_DULL
> +	NULL, "cpu", DV_DULL, CD_COCOVM
>  };
>
>  /*
> diff --git a/sys/arch/amd64/amd64/ioapic.c b/sys/arch/amd64/amd64/ioapic.c
> index 9989fdfeb29..40af6c4154d 100644
> --- a/sys/arch/amd64/amd64/ioapic.c
> +++ b/sys/arch/amd64/amd64/ioapic.c
> @@ -231,7 +231,7 @@ const struct cfattach ioapic_ca = {
>  };
>
>  struct cfdriver ioapic_cd = {
> -	NULL, "ioapic", DV_DULL
> +	NULL, "ioapic", DV_DULL, CD_COCOVM
>  };
>
>  int
> diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
> index 3462ac54559..7c540328d98 100644
> --- a/sys/arch/amd64/amd64/machdep.c
> +++ b/sys/arch/amd64/amd64/machdep.c
> @@ -1474,6 +1474,8 @@ init_x86_64(paddr_t first_avail)
>  		cpu_init_early_vctrap(first_avail);
>  		first_avail += 2 * NBPG;
>  	}
> +	if (ISSET(cpu_sev_guestmode, SEV_STAT_ENABLED))
> +		boothowto |= RB_COCOVM;
>
>  	/*
>  	 * locore0 mapped 3 pages for use before the pmap is initialized
> diff --git a/sys/arch/amd64/amd64/mainbus.c b/sys/arch/amd64/amd64/mainbus.c
> index 030f0b1212f..f77a67f5517 100644
> --- a/sys/arch/amd64/amd64/mainbus.c
> +++ b/sys/arch/amd64/amd64/mainbus.c
> @@ -83,7 +83,7 @@ const struct cfattach mainbus_ca = {
>  };
>
>  struct cfdriver mainbus_cd = {
> -	NULL, "mainbus", DV_DULL
> +	NULL, "mainbus", DV_DULL, CD_COCOVM
>  };
>
>  int	mainbus_print(void *, const char *);
> diff --git a/sys/arch/amd64/pci/acpipci.c b/sys/arch/amd64/pci/acpipci.c
> index 5b07e2d3aba..81d8ad3ced0 100644
> --- a/sys/arch/amd64/pci/acpipci.c
> +++ b/sys/arch/amd64/pci/acpipci.c
> @@ -76,7 +76,7 @@ const struct cfattach acpipci_ca = {
>  };
>
>  struct cfdriver acpipci_cd = {
> -	NULL, "acpipci", DV_DULL
> +	NULL, "acpipci", DV_DULL, CD_COCOVM
>  };
>
>  const char *acpipci_hids[] = {
> diff --git a/sys/arch/amd64/pci/pchb.c b/sys/arch/amd64/pci/pchb.c
> index 9b10011e2db..eb06df06b19 100644
> --- a/sys/arch/amd64/pci/pchb.c
> +++ b/sys/arch/amd64/pci/pchb.c
> @@ -122,7 +122,7 @@ const struct cfattach pchb_ca = {
>  };
>
>  struct cfdriver pchb_cd = {
> -	NULL, "pchb", DV_DULL
> +	NULL, "pchb", DV_DULL, CD_COCOVM
>  };
>
>  int	pchb_print(void *, const char *);
> diff --git a/sys/dev/acpi/acpi.c b/sys/dev/acpi/acpi.c
> index 7bcf56cab49..bb3645528c9 100644
> --- a/sys/dev/acpi/acpi.c
> +++ b/sys/dev/acpi/acpi.c
> @@ -184,7 +184,7 @@ struct acpi_softc *acpi_softc;
>  extern struct aml_node aml_root;
>
>  struct cfdriver acpi_cd = {
> -	NULL, "acpi", DV_DULL
> +	NULL, "acpi", DV_DULL, CD_COCOVM
>  };
>
>  uint8_t
> diff --git a/sys/dev/acpi/acpicmos.c b/sys/dev/acpi/acpicmos.c
> index 6e424e26530..068787c1922 100644
> --- a/sys/dev/acpi/acpicmos.c
> +++ b/sys/dev/acpi/acpicmos.c
> @@ -37,7 +37,7 @@ const struct cfattach acpicmos_ca = {
>  };
>
>  struct cfdriver acpicmos_cd = {
> -	NULL, "acpicmos", DV_DULL
> +	NULL, "acpicmos", DV_DULL, CD_COCOVM
>  };
>
>  const char *acpicmos_hids[] = {
> diff --git a/sys/dev/acpi/acpicpu_x86.c b/sys/dev/acpi/acpicpu_x86.c
> index 15f0ceeaeae..a5ddc55b1b3 100644
> --- a/sys/dev/acpi/acpicpu_x86.c
> +++ b/sys/dev/acpi/acpicpu_x86.c
> @@ -183,7 +183,7 @@ const struct cfattach acpicpu_ca = {
>  };
>
>  struct cfdriver acpicpu_cd = {
> -	NULL, "acpicpu", DV_DULL
> +	NULL, "acpicpu", DV_DULL, CD_COCOVM
>  };
>
>  const char *acpicpu_hids[] = {
> diff --git a/sys/dev/acpi/acpihpet.c b/sys/dev/acpi/acpihpet.c
> index dd992132678..dd25309c1c5 100644
> --- a/sys/dev/acpi/acpihpet.c
> +++ b/sys/dev/acpi/acpihpet.c
> @@ -79,7 +79,7 @@ const struct cfattach acpihpet_ca = {
>  };
>
>  struct cfdriver acpihpet_cd = {
> -	NULL, "acpihpet", DV_DULL
> +	NULL, "acpihpet", DV_DULL, CD_COCOVM
>  };
>
>  uint64_t
> diff --git a/sys/dev/acpi/acpimadt.c b/sys/dev/acpi/acpimadt.c
> index 3faed32b355..6359ffd925b 100644
> --- a/sys/dev/acpi/acpimadt.c
> +++ b/sys/dev/acpi/acpimadt.c
> @@ -48,7 +48,7 @@ const struct cfattach acpimadt_ca = {
>  };
>
>  struct cfdriver acpimadt_cd = {
> -	NULL, "acpimadt", DV_DULL
> +	NULL, "acpimadt", DV_DULL, CD_COCOVM
>  };
>
>  int acpimadt_validate(struct acpi_madt *);
> diff --git a/sys/dev/acpi/acpimcfg.c b/sys/dev/acpi/acpimcfg.c
> index f3e520882aa..b7df8a297a0 100644
> --- a/sys/dev/acpi/acpimcfg.c
> +++ b/sys/dev/acpi/acpimcfg.c
> @@ -31,7 +31,7 @@ const struct cfattach acpimcfg_ca = {
>  };
>
>  struct cfdriver acpimcfg_cd = {
> -	NULL, "acpimcfg", DV_DULL
> +	NULL, "acpimcfg", DV_DULL, CD_COCOVM
>  };
>
>  int
> diff --git a/sys/dev/acpi/acpiprt.c b/sys/dev/acpi/acpiprt.c
> index 39de79dcfca..1011ec68600 100644
> --- a/sys/dev/acpi/acpiprt.c
> +++ b/sys/dev/acpi/acpiprt.c
> @@ -77,7 +77,7 @@ const struct cfattach acpiprt_ca = {
>  };
>
>  struct cfdriver acpiprt_cd = {
> -	NULL, "acpiprt", DV_DULL
> +	NULL, "acpiprt", DV_DULL, CD_COCOVM
>  };
>
>  void	acpiprt_prt_add(struct acpiprt_softc *, struct aml_value *);
> diff --git a/sys/dev/acpi/acpitimer.c b/sys/dev/acpi/acpitimer.c
> index 11a8b9eccf3..498146a592e 100644
> --- a/sys/dev/acpi/acpitimer.c
> +++ b/sys/dev/acpi/acpitimer.c
> @@ -55,7 +55,7 @@ const struct cfattach acpitimer_ca = {
>  };
>
>  struct cfdriver acpitimer_cd = {
> -	NULL, "acpitimer", DV_DULL
> +	NULL, "acpitimer", DV_DULL, CD_COCOVM
>  };
>
>  int
> diff --git a/sys/dev/efi/efi.c b/sys/dev/efi/efi.c
> index 43a774253fa..e600a3b1e47 100644
> --- a/sys/dev/efi/efi.c
> +++ b/sys/dev/efi/efi.c
> @@ -24,7 +24,7 @@
>  #include <machine/efivar.h>
>
>  struct cfdriver efi_cd = {
> -	NULL, "efi", DV_DULL
> +	NULL, "efi", DV_DULL, CD_COCOVM
>  };
>
>  int	efiioc_get_table(struct efi_softc *sc, void *);
> diff --git a/sys/dev/ic/com.c b/sys/dev/ic/com.c
> index dd45e3c901c..da29f82243b 100644
> --- a/sys/dev/ic/com.c
> +++ b/sys/dev/ic/com.c
> @@ -96,7 +96,7 @@ void	compwroff(struct com_softc *);
>  void	cominit(bus_space_tag_t, bus_space_handle_t, int, int);
>
>  struct cfdriver com_cd = {
> -	NULL, "com", DV_TTY
> +	NULL, "com", DV_TTY, CD_COCOVM
>  };
>
>  int	comdefaultrate = TTYDEF_SPEED;
> diff --git a/sys/dev/isa/isa.c b/sys/dev/isa/isa.c
> index 2d11dc33a84..2a799f8a82a 100644
> --- a/sys/dev/isa/isa.c
> +++ b/sys/dev/isa/isa.c
> @@ -62,6 +62,7 @@
>  #include <sys/malloc.h>
>  #include <sys/device.h>
>  #include <sys/extent.h>
> +#include <sys/reboot.h>
>
>  #include <dev/isa/isareg.h>
>  #include <dev/isa/isavar.h>
> @@ -84,7 +85,7 @@ const struct cfattach isa_ca = {
>  };
>
>  struct cfdriver isa_cd = {
> -	NULL, "isa", DV_DULL, CD_INDIRECT
> +	NULL, "isa", DV_DULL, CD_INDIRECT | CD_COCOVM
>  };
>
>  int
> @@ -218,6 +219,10 @@ isascan(struct device *parent, void *match)
>  	ia.ipa_ndrq = 2;
>  	ia.ia_delaybah = sc->sc_delaybah;
>
> +	if (ISSET(boothowto, RB_COCOVM) &&
> +	    !ISSET(cf->cf_driver->cd_mode, CD_COCOVM))
> +		return;
> +
>  	if (cf->cf_fstate == FSTATE_STAR) {
>  		struct isa_attach_args ia2 = ia;
>
> diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c
> index c0376842914..d7601dd976e 100644
> --- a/sys/dev/pci/pci.c
> +++ b/sys/dev/pci/pci.c
> @@ -90,7 +90,7 @@ const struct cfattach pci_ca = {
>  };
>
>  struct cfdriver pci_cd = {
> -	NULL, "pci", DV_DULL
> +	NULL, "pci", DV_DULL, CD_COCOVM
>  };
>
>  int	pci_ndomains;
> diff --git a/sys/dev/pci/ppb.c b/sys/dev/pci/ppb.c
> index cf7cb120cc1..f6ab05f9168 100644
> --- a/sys/dev/pci/ppb.c
> +++ b/sys/dev/pci/ppb.c
> @@ -113,7 +113,7 @@ const struct cfattach ppb_ca = {
>  };
>
>  struct cfdriver ppb_cd = {
> -	NULL, "ppb", DV_DULL
> +	NULL, "ppb", DV_DULL, CD_COCOVM
>  };
>
>  void	ppb_alloc_busrange(struct ppb_softc *, struct pci_attach_args *,
> diff --git a/sys/dev/pv/if_vio.c b/sys/dev/pv/if_vio.c
> index a94945a8ea0..458f98c6a7a 100644
> --- a/sys/dev/pv/if_vio.c
> +++ b/sys/dev/pv/if_vio.c
> @@ -382,7 +382,7 @@ const struct cfattach vio_ca = {
>  };
>
>  struct cfdriver vio_cd = {
> -	NULL, "vio", DV_IFNET
> +	NULL, "vio", DV_IFNET, CD_COCOVM
>  };
>
>  int
> diff --git a/sys/dev/pv/pvbus.c b/sys/dev/pv/pvbus.c
> index 165fcc9fbff..a482072de4b 100644
> --- a/sys/dev/pv/pvbus.c
> +++ b/sys/dev/pv/pvbus.c
> @@ -68,7 +68,8 @@ const struct cfattach pvbus_ca = {
>  struct cfdriver pvbus_cd = {
>  	NULL,
>  	"pvbus",
> -	DV_DULL
> +	DV_DULL,
> +	CD_COCOVM
>  };
>
>  struct pvbus_type {
> diff --git a/sys/dev/pv/pvclock.c b/sys/dev/pv/pvclock.c
> index 89eff0ce248..fd69960ddda 100644
> --- a/sys/dev/pv/pvclock.c
> +++ b/sys/dev/pv/pvclock.c
> @@ -125,7 +125,8 @@ const struct cfattach pvclock_ca = {
>  struct cfdriver pvclock_cd = {
>  	NULL,
>  	"pvclock",
> -	DV_DULL
> +	DV_DULL,
> +	CD_COCOVM
>  };
>
>  struct timecounter pvclock_timecounter = {
> diff --git a/sys/dev/pv/vioblk.c b/sys/dev/pv/vioblk.c
> index 7f7a518332f..761ce73a847 100644
> --- a/sys/dev/pv/vioblk.c
> +++ b/sys/dev/pv/vioblk.c
> @@ -146,7 +146,7 @@ const struct cfattach vioblk_ca = {
>  };
>
>  struct cfdriver vioblk_cd = {
> -	NULL, "vioblk", DV_DULL
> +	NULL, "vioblk", DV_DULL, CD_COCOVM
>  };
>
>  const struct scsi_adapter vioblk_switch = {
> diff --git a/sys/dev/pv/viocon.c b/sys/dev/pv/viocon.c
> index 95a1e875579..1d24074c54d 100644
> --- a/sys/dev/pv/viocon.c
> +++ b/sys/dev/pv/viocon.c
> @@ -144,7 +144,7 @@ const struct cfattach viocon_ca = {
>  };
>
>  struct cfdriver viocon_cd = {
> -	NULL, "viocon", DV_TTY
> +	NULL, "viocon", DV_TTY, CD_COCOVM
>  };
>
>  static inline struct viocon_softc *
> diff --git a/sys/dev/pv/viornd.c b/sys/dev/pv/viornd.c
> index 484f7ce1be0..9eeb6115f3e 100644
> --- a/sys/dev/pv/viornd.c
> +++ b/sys/dev/pv/viornd.c
> @@ -66,7 +66,7 @@ const struct cfattach viornd_ca = {
>  };
>
>  struct cfdriver viornd_cd = {
> -	NULL, "viornd", DV_DULL
> +	NULL, "viornd", DV_DULL, CD_COCOVM
>  };
>
>  int
> diff --git a/sys/dev/pv/virtio.c b/sys/dev/pv/virtio.c
> index ac0432dc9f9..4a8d140f797 100644
> --- a/sys/dev/pv/virtio.c
> +++ b/sys/dev/pv/virtio.c
> @@ -48,7 +48,7 @@ void		 vq_free_entry(struct virtqueue *, struct vq_entry *);
>  struct vq_entry	*vq_alloc_entry(struct virtqueue *);
>
>  struct cfdriver virtio_cd = {
> -	NULL, "virtio", DV_DULL
> +	NULL, "virtio", DV_DULL, CD_COCOVM
>  };
>
>  static const char * const virtio_device_name[] = {
> diff --git a/sys/dev/pv/vmmci.c b/sys/dev/pv/vmmci.c
> index 984626393cd..18930c62766 100644
> --- a/sys/dev/pv/vmmci.c
> +++ b/sys/dev/pv/vmmci.c
> @@ -72,7 +72,7 @@ const struct cfattach vmmci_ca = {
>  #define VMMCI_F_SYNCRTC		(1ULL<<2)
>
>  struct cfdriver vmmci_cd = {
> -	NULL, "vmmci", DV_DULL
> +	NULL, "vmmci", DV_DULL, CD_COCOVM
>  };
>
>  int
> diff --git a/sys/dev/softraid.c b/sys/dev/softraid.c
> index c10ebeaaa93..41929692397 100644
> --- a/sys/dev/softraid.c
> +++ b/sys/dev/softraid.c
> @@ -88,7 +88,7 @@ const struct cfattach softraid_ca = {
>  };
>
>  struct cfdriver softraid_cd = {
> -	NULL, "softraid", DV_DULL
> +	NULL, "softraid", DV_DULL, CD_COCOVM
>  };
>
>  /* scsi & discipline */
> diff --git a/sys/dev/vscsi.c b/sys/dev/vscsi.c
> index 31885a6b9c9..2e2deb25b1f 100644
> --- a/sys/dev/vscsi.c
> +++ b/sys/dev/vscsi.c
> @@ -89,7 +89,8 @@ const struct cfattach vscsi_ca = {
>  struct cfdriver vscsi_cd = {
>  	NULL,
>  	"vscsi",
> -	DV_DULL
> +	DV_DULL,
> +	CD_COCOVM
>  };
>
>  void		vscsi_cmd(struct scsi_xfer *);
> diff --git a/sys/kern/subr_autoconf.c b/sys/kern/subr_autoconf.c
> index 41633140dc6..eec9eef15ce 100644
> --- a/sys/kern/subr_autoconf.c
> +++ b/sys/kern/subr_autoconf.c
> @@ -216,6 +216,9 @@ config_search(cfmatch_t fn, struct device *parent, void *aux)
>  			if (cf->cf_driver->cd_class == DV_TAPE)
>  				continue;
>  		}
> +		if (ISSET(boothowto, RB_COCOVM) &&
> +		    !ISSET(cf->cf_driver->cd_mode, CD_COCOVM))
> +			continue;
>  		for (p = cf->cf_parents; *p >= 0; p++)
>  			if (parent->dv_cfdata == &cfdata[*p])
>  				mapply(&m, cf);
> diff --git a/sys/scsi/mpath.c b/sys/scsi/mpath.c
> index c94a4ff5cf7..090c78c35f1 100644
> --- a/sys/scsi/mpath.c
> +++ b/sys/scsi/mpath.c
> @@ -79,7 +79,8 @@ const struct cfattach mpath_ca = {
>  struct cfdriver mpath_cd = {
>  	NULL,
>  	"mpath",
> -	DV_DULL
> +	DV_DULL,
> +	CD_COCOVM
>  };
>
>  void		mpath_cmd(struct scsi_xfer *);
> diff --git a/sys/scsi/scsiconf.c b/sys/scsi/scsiconf.c
> index 495020a23a3..2f9ab1b15d0 100644
> --- a/sys/scsi/scsiconf.c
> +++ b/sys/scsi/scsiconf.c
> @@ -102,7 +102,7 @@ const struct cfattach scsibus_ca = {
>  };
>
>  struct cfdriver scsibus_cd = {
> -	NULL, "scsibus", DV_DULL
> +	NULL, "scsibus", DV_DULL, CD_COCOVM
>  };
>
>  struct scsi_quirk_inquiry_pattern {
> diff --git a/sys/scsi/sd.c b/sys/scsi/sd.c
> index 9b02314c679..085ad01cd78 100644
> --- a/sys/scsi/sd.c
> +++ b/sys/scsi/sd.c
> @@ -116,7 +116,7 @@ const struct cfattach sd_ca = {
>  };
>
>  struct cfdriver sd_cd = {
> -	NULL, "sd", DV_DISK
> +	NULL, "sd", DV_DISK, CD_COCOVM
>  };
>
>  const struct scsi_inquiry_pattern sd_patterns[] = {
> diff --git a/sys/sys/device.h b/sys/sys/device.h
> index 5dccec16cf8..2c4171017ec 100644
> --- a/sys/sys/device.h
> +++ b/sys/sys/device.h
> @@ -139,6 +139,7 @@ struct cfattach {
>  /* For cd_mode, below */
>  #define CD_INDIRECT		1
>  #define CD_SKIPHIBERNATE	2
> +#define CD_COCOVM		4
>
>  struct cfdriver {
>  	void	**cd_devs;		/* devices found */
> diff --git a/sys/sys/reboot.h b/sys/sys/reboot.h
> index bf3e7f82680..1998f21691b 100644
> --- a/sys/sys/reboot.h
> +++ b/sys/sys/reboot.h
> @@ -59,6 +59,7 @@
>  #define	RB_RESET	0x08000	/* just reset, no cleanup  */
>  #define	RB_GOODRANDOM	0x10000	/* excellent random seed loaded */
>  #define	RB_UNHIBERNATE	0x20000	/* unhibernate */
> +#define RB_COCOVM	0x40000	/* VM booting with SEV enabled */
>
>  /*
>   * Constants for converting boot-style device number to type,