Add vds(4) and vdsp(4), implementing the vDisk server side protocol. This

makes it possible to run an OpenBSD guest domain on top of a virtiual disk
backed by a disk image on a filesystem on OpenBSD control or service domain.

Probably doesn't support running Solaris or Linux yet.  Haven't tried those
yet because booting their installers in a guest domain is way too painful!

4 files changed, 1261 insertions, 2 deletions

diff --git a/sys/arch/sparc64/conf/GENERIC b/sys/arch/sparc64/conf/GENERIC
index 1055f74d58b..b735480cf97 100644
--- a/sys/arch/sparc64/conf/GENERIC
+++ b/sys/arch/sparc64/conf/GENERIC
@@ -1,4 +1,4 @@
-#	$OpenBSD: GENERIC,v 1.249 2009/12/21 22:17:37 matthieu Exp $
+#	$OpenBSD: GENERIC,v 1.250 2009/12/31 11:58:41 kettenis Exp $
 #
 # For further information on compiling OpenBSD kernels, see the config(8)
 # man page.
@@ -354,6 +354,8 @@ scsibus* at vdsk?
 vnet*	at cbus?
 vcc*	at cbus?
 vcctty*	at vcc?
+vds*	at cbus?
+vdsp*	at vds?
 vsw*	at cbus?
 vnet*	at vsw?
 
diff --git a/sys/arch/sparc64/conf/files.sparc64 b/sys/arch/sparc64/conf/files.sparc64
index 6771c7daff5..50a2305cc02 100644
--- a/sys/arch/sparc64/conf/files.sparc64
+++ b/sys/arch/sparc64/conf/files.sparc64
@@ -1,4 +1,4 @@
-#	$OpenBSD: files.sparc64,v 1.129 2009/10/04 17:49:33 deraadt Exp $
+#	$OpenBSD: files.sparc64,v 1.130 2009/12/31 11:58:41 kettenis Exp $
 #	$NetBSD: files.sparc64,v 1.50 2001/08/10 20:53:50 eeh Exp $
 
 # maxpartitions must be first item in files.${ARCH}
@@ -429,6 +429,16 @@ file	arch/sparc64/dev/vrtc.c			vrtc
 define	ldc
 file	arch/sparc64/dev/ldc.c			ldc
 
+# Virtual disk server
+device	vds {}
+attach	vds at cbus
+file	arch/sparc64/dev/vds.c			vds
+
+# Virtual disk server port
+device	vdsp: ldc
+attach	vdsp at vds
+file	arch/sparc64/dev/vdsp.c			vdsp
+
 # Virtual disk
 device	vdsk: ldc, scsi
 attach	vdsk at cbus
diff --git a/sys/arch/sparc64/dev/vds.c b/sys/arch/sparc64/dev/vds.c
new file mode 100644
index 00000000000..b02d7473a06
--- /dev/null
+++ b/sys/arch/sparc64/dev/vds.c
@@ -0,0 +1,137 @@
+/*	$OpenBSD: vds.c,v 1.1 2009/12/31 11:58:41 kettenis Exp $	*/
+/*
+ * Copyright (c) 2009 Mark Kettenis
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/param.h>
+#include <sys/buf.h>
+#include <sys/device.h>
+#include <sys/malloc.h>
+#include <sys/systm.h>
+
+#include <machine/autoconf.h>
+#include <machine/hypervisor.h>
+#include <machine/mdesc.h>
+
+#include <sparc64/dev/cbusvar.h>
+
+#ifdef VDS_DEBUG
+#define DPRINTF(x)	printf x
+#else
+#define DPRINTF(x)
+#endif
+
+struct vds_softc {
+	struct device	sc_dv;
+	bus_space_tag_t	sc_bustag;
+	bus_dma_tag_t	sc_dmatag;
+};
+
+int	vds_match(struct device *, void *, void *);
+void	vds_attach(struct device *, struct device *, void *);
+
+struct cfattach vds_ca = {
+	sizeof(struct vds_softc), vds_match, vds_attach
+};
+
+struct cfdriver vds_cd = {
+	NULL, "vds", DV_DULL
+};
+
+void	vds_get_channel_endpoint(int, struct cbus_attach_args *);
+
+int
+vds_match(struct device *parent, void *match, void *aux)
+{
+	struct cbus_attach_args *ca = aux;
+
+	if (strcmp(ca->ca_name, "virtual-disk-server") == 0)
+		return (1);
+
+	return (0);
+}
+
+void
+vds_attach(struct device *parent, struct device *self, void *aux)
+{
+	struct cbus_attach_args *ca = aux;
+	struct cbus_attach_args nca;
+	struct md_header *hdr;
+	struct md_element *elem;
+	const char *name_blk;
+	const char *str;
+	int idx;
+	int arc;
+
+	printf("\n");
+
+	hdr = (struct md_header *)mdesc;
+	elem = (struct md_element *)(mdesc + sizeof(struct md_header));
+	name_blk = mdesc + sizeof(struct md_header) + hdr->node_blk_sz;
+
+	idx = ca->ca_idx;
+	for (; elem[idx].tag != 'E'; idx++) {
+		str = name_blk + elem[idx].name_offset;
+		if (elem[idx].tag != 'a' || strcmp(str, "fwd") != 0)
+			continue;
+
+		arc = elem[idx].d.val;
+		str = name_blk + elem[arc].name_offset;
+		if (strcmp(str, "virtual-device-port") == 0) {
+			bzero(&nca, sizeof(nca));
+			nca.ca_name = "vds-port";
+			nca.ca_node = ca->ca_node;
+			nca.ca_bustag = ca->ca_bustag;
+			nca.ca_dmatag = ca->ca_dmatag;
+			vds_get_channel_endpoint(arc, &nca);
+			config_found(self, &nca, cbus_print);
+		}
+	}
+}
+
+void
+vds_get_channel_endpoint(int idx, struct cbus_attach_args *ca)
+{
+	struct md_header *hdr;
+	struct md_element *elem;
+	const char *name_blk;
+	const char *str;
+	int arc;
+
+	hdr = (struct md_header *)mdesc;
+	elem = (struct md_element *)(mdesc + sizeof(struct md_header));
+	name_blk = mdesc + sizeof(struct md_header) + hdr->node_blk_sz;
+
+	ca->ca_idx = idx;
+
+	ca->ca_id = -1;
+	ca->ca_tx_ino = -1;
+	ca->ca_rx_ino = -1;
+
+	for (; elem[idx].tag != 'E'; idx++) {
+		str = name_blk + elem[idx].name_offset;
+		if (elem[idx].tag != 'a' || strcmp(str, "fwd") != 0)
+			continue;
+
+		arc = elem[idx].d.val;
+		str = name_blk + elem[arc].name_offset;
+		if (strcmp(str, "channel-endpoint") == 0) {
+			ca->ca_id = mdesc_get_prop_val(arc, "id");
+			ca->ca_tx_ino = mdesc_get_prop_val(arc, "tx-ino");
+			ca->ca_rx_ino = mdesc_get_prop_val(arc, "rx-ino");
+			return;
+		}
+	}
+}
diff --git a/sys/arch/sparc64/dev/vdsp.c b/sys/arch/sparc64/dev/vdsp.c
new file mode 100644
index 00000000000..6c0d286934a
--- /dev/null
+++ b/sys/arch/sparc64/dev/vdsp.c
@@ -0,0 +1,1110 @@
+/*	$OpenBSD: vdsp.c,v 1.1 2009/12/31 11:58:41 kettenis Exp $	*/
+/*
+ * Copyright (c) 2009 Mark Kettenis
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/param.h>
+#include <sys/buf.h>
+#include <sys/device.h>
+#include <sys/fcntl.h>
+#include <sys/malloc.h>
+#include <sys/namei.h>
+#include <sys/systm.h>
+#include <sys/vnode.h>
+#include <sys/workq.h>
+
+#include <machine/autoconf.h>
+#include <machine/hypervisor.h>
+#include <machine/mdesc.h>
+
+#include <uvm/uvm.h>
+
+#include <scsi/scsi_all.h>
+#include <scsi/scsi_disk.h>
+#include <scsi/scsiconf.h>
+
+#include <sparc64/dev/cbusvar.h>
+#include <sparc64/dev/ldcvar.h>
+#include <sparc64/dev/viovar.h>
+
+#ifdef VDSP_DEBUG
+#define DPRINTF(x)	printf x
+#else
+#define DPRINTF(x)
+#endif
+
+#define VDSK_TX_ENTRIES		64
+#define VDSK_RX_ENTRIES		64
+
+#define VDSK_MAX_DESCRIPTORS	1024
+
+struct vd_attr_info {
+	struct vio_msg_tag	tag;
+	uint8_t			xfer_mode;
+	uint8_t			vd_type;
+	uint8_t			vd_mtype;
+	uint8_t			_reserved1;
+	uint32_t		vdisk_block_size;
+	uint64_t		operations;
+	uint64_t		vdisk_size;
+	uint64_t		max_xfer_sz;
+	uint64_t		_reserved2[2];
+};
+
+#define VD_DISK_TYPE_SLICE	0x01
+#define VD_DISK_TYPE_DISK	0x02
+
+#define VD_MEDIA_TYPE_FIXED	0x01
+#define VD_MEDIA_TYPE_CD	0x02
+#define VD_MEDIA_TYPE_DVD	0x03
+
+/* vDisk version 1.0. */
+#define VD_OP_BREAD		0x01
+#define VD_OP_BWRITE		0x02
+#define VD_OP_FLUSH		0x03
+#define VD_OP_GET_WCE		0x04
+#define VD_OP_SET_WCE		0x05
+#define VD_OP_GET_VTOC		0x06
+#define VD_OP_SET_VTOC		0x07
+#define VD_OP_GET_DISKGEOM	0x08
+#define VD_OP_SET_DISKGEOM	0x09
+#define VD_OP_GET_DEVID		0x0b
+#define VD_OP_GET_EFI		0x0c
+#define VD_OP_SET_EFI		0x0d
+
+/* vDisk version 1.1 */
+#define VD_OP_SCSICMD		0x0a
+#define VD_OP_RESET		0x0e
+#define VD_OP_GET_ACCESS	0x0f
+#define VD_OP_SET_ACCESS	0x10
+#define VD_OP_GET_CAPACITY	0x11
+
+struct vd_desc {
+	struct vio_dring_hdr	hdr;
+	uint64_t		req_id;
+	uint8_t			operation;
+	uint8_t			slice;
+	uint16_t		_reserved1;
+	uint32_t		status;
+	uint64_t		offset;
+	uint64_t		size;
+	uint32_t		ncookies;
+	uint32_t		_reserved2;
+	struct ldc_cookie	cookie[MAXPHYS / PAGE_SIZE];
+};
+
+#define VD_SLICE_NONE		0xff
+
+struct vdsk_desc_msg {
+	struct vio_msg_tag	tag;
+	uint64_t		seq_no;
+	uint64_t		desc_handle;
+	uint64_t		req_id;
+	uint8_t			operation;
+	uint8_t			slice;
+	uint16_t		_reserved1;
+	uint32_t		status;
+	uint64_t		offset;
+	uint64_t		size;
+	uint32_t		ncookies;
+	uint32_t		_reserved2;
+	struct ldc_cookie	cookie[1];
+};
+
+/*
+ * For now, we only support vDisk 1.0.
+ */
+#define VDSK_MAJOR	1
+#define VDSK_MINOR	0
+
+struct vdsp_softc {
+	struct device	sc_dv;
+	int		sc_idx;
+	bus_space_tag_t	sc_bustag;
+	bus_dma_tag_t	sc_dmatag;
+
+	uint64_t	sc_tx_sysino;
+	uint64_t	sc_rx_sysino;
+	void		*sc_tx_ih;
+	void		*sc_rx_ih;
+
+	struct ldc_conn	sc_lc;
+
+	uint16_t	sc_vio_state;
+#define VIO_SND_VER_INFO	0x0001
+#define VIO_ACK_VER_INFO	0x0002
+#define VIO_RCV_VER_INFO	0x0004
+#define VIO_SND_ATTR_INFO	0x0008
+#define VIO_ACK_ATTR_INFO	0x0010
+#define VIO_RCV_ATTR_INFO	0x0020
+#define VIO_SND_DRING_REG	0x0040
+#define VIO_ACK_DRING_REG	0x0080
+#define VIO_RCV_DRING_REG	0x0100
+#define VIO_SND_RDX		0x0200
+#define VIO_ACK_RDX		0x0400
+#define VIO_RCV_RDX		0x0800
+
+	uint16_t	sc_major;
+	uint16_t	sc_minor;
+
+	uint8_t		sc_xfer_mode;
+
+	uint32_t	sc_local_sid;
+	uint64_t	sc_seq_no;
+
+	uint64_t	sc_dring_ident;
+	uint32_t	sc_num_descriptors;
+	uint32_t	sc_descriptor_size;
+	struct ldc_cookie sc_dring_cookie;
+
+	struct vd_desc	*sc_vd;
+
+	int		sc_tx_cnt;
+	int		sc_tx_prod;
+	int		sc_tx_cons;
+
+	uint32_t	sc_vdisk_block_size;
+	uint64_t	sc_vdisk_size;
+
+	struct vnode	*sc_vp;
+};
+
+int	vdsp_match(struct device *, void *, void *);
+void	vdsp_attach(struct device *, struct device *, void *);
+
+struct cfattach vdsp_ca = {
+	sizeof(struct vdsp_softc), vdsp_match, vdsp_attach
+};
+
+struct cfdriver vdsp_cd = {
+	NULL, "vdsp", DV_DULL
+};
+
+int	vdsp_tx_intr(void *);
+int	vdsp_rx_intr(void *);
+
+void	vdsp_rx_data(struct ldc_conn *, struct ldc_pkt *);
+void	vdsp_rx_vio_ctrl(struct vdsp_softc *, struct vio_msg *);
+void	vdsp_rx_vio_ver_info(struct vdsp_softc *, struct vio_msg_tag *);
+void	vdsp_rx_vio_attr_info(struct vdsp_softc *, struct vio_msg_tag *);
+void	vdsp_rx_vio_dring_reg(struct vdsp_softc *, struct vio_msg_tag *);
+void	vdsp_rx_vio_rdx(struct vdsp_softc *sc, struct vio_msg_tag *);
+void	vdsp_rx_vio_data(struct vdsp_softc *sc, struct vio_msg *);
+void	vdsp_rx_vio_dring_data(struct vdsp_softc *sc,
+	    struct vio_msg_tag *);
+void	vdsp_rx_vio_desc_data(struct vdsp_softc *sc, struct vio_msg_tag *);
+
+void	vdsp_ldc_reset(struct ldc_conn *);
+void	vdsp_ldc_start(struct ldc_conn *);
+
+void	vdsp_sendmsg(struct vdsp_softc *, void *, size_t);
+
+void	vdsp_mountroot(void *);
+void	vdsp_open(void *, void *);
+void	vdsp_alloc(void *, void *);
+void	vdsp_read(void *, void *);
+void	vdsp_read_dring(void *, void *);
+void	vdsp_write_dring(void *, void *);
+void	vdsp_flush_dring(void *, void *);
+
+int
+vdsp_match(struct device *parent, void *match, void *aux)
+{
+	struct cbus_attach_args *ca = aux;
+
+	if (strcmp(ca->ca_name, "vds-port") == 0)
+		return (1);
+
+	return (0);
+}
+
+void
+vdsp_attach(struct device *parent, struct device *self, void *aux)
+{
+	struct vdsp_softc *sc = (struct vdsp_softc *)self;
+	struct cbus_attach_args *ca = aux;
+	struct ldc_conn *lc;
+
+	sc->sc_idx = ca->ca_idx;
+	sc->sc_bustag = ca->ca_bustag;
+	sc->sc_dmatag = ca->ca_dmatag;
+
+	if (cbus_intr_map(ca->ca_node, ca->ca_tx_ino, &sc->sc_tx_sysino) ||
+	    cbus_intr_map(ca->ca_node, ca->ca_rx_ino, &sc->sc_rx_sysino)) {
+		printf(": can't map interrupt\n");
+		return;
+	}
+	printf(": ivec 0x%lx, 0x%lx", sc->sc_tx_sysino, sc->sc_tx_sysino);
+
+	/*
+	 * Un-configure queues before registering interrupt handlers,
+	 * such that we dont get any stale LDC packets or events.
+	 */
+	hv_ldc_tx_qconf(ca->ca_id, 0, 0);
+	hv_ldc_rx_qconf(ca->ca_id, 0, 0);
+
+	sc->sc_tx_ih = bus_intr_establish(ca->ca_bustag, sc->sc_tx_sysino,
+	    IPL_BIO, 0, vdsp_tx_intr, sc, sc->sc_dv.dv_xname);
+	sc->sc_rx_ih = bus_intr_establish(ca->ca_bustag, sc->sc_rx_sysino,
+	    IPL_BIO, 0, vdsp_rx_intr, sc, sc->sc_dv.dv_xname);
+	if (sc->sc_tx_ih == NULL || sc->sc_rx_ih == NULL) {
+		printf(", can't establish interrupt\n");
+		return;
+	}
+
+	/*
+	 * Disable interrupts while we have no queues allocated.
+	 * Otherwise we may end up with an interrupt storm as soon as
+	 * our peer places a packet in their transmit queue.
+	 */
+	cbus_intr_setenabled(sc->sc_tx_sysino, INTR_DISABLED);
+	cbus_intr_setenabled(sc->sc_rx_sysino, INTR_DISABLED);
+
+	lc = &sc->sc_lc;
+	lc->lc_id = ca->ca_id;
+	lc->lc_sc = sc;
+	lc->lc_reset = vdsp_ldc_reset;
+	lc->lc_start = vdsp_ldc_start;
+	lc->lc_rx_data = vdsp_rx_data;
+
+	lc->lc_txq = ldc_queue_alloc(sc->sc_dmatag, VDSK_TX_ENTRIES);
+	if (lc->lc_txq == NULL) {
+		printf(", can't allocate tx queue\n");
+		return;
+	}
+
+	lc->lc_rxq = ldc_queue_alloc(sc->sc_dmatag, VDSK_RX_ENTRIES);
+	if (lc->lc_rxq == NULL) {
+		printf(", can't allocate rx queue\n");
+		goto free_txqueue;
+	}
+
+	printf("\n");
+
+	mountroothook_establish(vdsp_mountroot, sc);
+	return;
+
+#if 0
+free_rxqueue:
+	ldc_queue_free(sc->sc_dmatag, lc->lc_rxq);
+#endif
+free_txqueue:
+	ldc_queue_free(sc->sc_dmatag, lc->lc_txq);
+}
+
+int
+vdsp_tx_intr(void *arg)
+{
+	struct vdsp_softc *sc = arg;
+	struct ldc_conn *lc = &sc->sc_lc;
+	uint64_t tx_head, tx_tail, tx_state;
+
+	hv_ldc_tx_get_state(lc->lc_id, &tx_head, &tx_tail, &tx_state);
+	if (tx_state != lc->lc_tx_state) {
+		switch (tx_state) {
+		case LDC_CHANNEL_DOWN:
+			DPRINTF(("Tx link down\n"));
+			break;
+		case LDC_CHANNEL_UP:
+			DPRINTF(("Tx link up\n"));
+			break;
+		case LDC_CHANNEL_RESET:
+			DPRINTF(("Tx link reset\n"));
+			break;
+		}
+		lc->lc_tx_state = tx_state;
+	}
+
+	return (1);
+}
+
+int
+vdsp_rx_intr(void *arg)
+{
+	struct vdsp_softc *sc = arg;
+	struct ldc_conn *lc = &sc->sc_lc;
+	uint64_t rx_head, rx_tail, rx_state;
+	struct ldc_pkt *lp;
+	int err;
+
+	err = hv_ldc_rx_get_state(lc->lc_id, &rx_head, &rx_tail, &rx_state);
+	if (err == H_EINVAL)
+		return (0);
+	if (err != H_EOK) {
+		printf("hv_ldc_rx_get_state %d\n", err);
+		return (0);
+	}
+
+	if (rx_state != lc->lc_rx_state) {
+		switch (rx_state) {
+		case LDC_CHANNEL_DOWN:
+			DPRINTF(("Rx link down\n"));
+			lc->lc_tx_seqid = 0;
+			lc->lc_state = 0;
+			lc->lc_reset(lc);
+			break;
+		case LDC_CHANNEL_UP:
+			DPRINTF(("Rx link up\n"));
+			break;
+		case LDC_CHANNEL_RESET:
+			DPRINTF(("Rx link reset\n"));
+			lc->lc_tx_seqid = 0;
+			lc->lc_state = 0;
+			lc->lc_reset(lc);
+			break;
+		}
+		lc->lc_rx_state = rx_state;
+		return (1);
+	}
+
+	if (lc->lc_rx_state == LDC_CHANNEL_DOWN)
+		return (1);
+
+	lp = (struct ldc_pkt *)(lc->lc_rxq->lq_va + rx_head);
+	switch (lp->type) {
+	case LDC_CTRL:
+		ldc_rx_ctrl(lc, lp);
+		break;
+
+	case LDC_DATA:
+		ldc_rx_data(lc, lp);
+		break;
+
+	default:
+		DPRINTF(("0x%02x/0x%02x/0x%02x\n", lp->type, lp->stype,
+		    lp->ctrl));
+		ldc_reset(lc);
+		break;
+	}
+
+	rx_head += sizeof(*lp);
+	rx_head &= ((lc->lc_rxq->lq_nentries * sizeof(*lp)) - 1);
+	err = hv_ldc_rx_set_qhead(lc->lc_id, rx_head);
+	if (err != H_EOK)
+		printf("%s: hv_ldc_rx_set_qhead %d\n", __func__, err);
+
+	return (1);
+}
+
+void
+vdsp_rx_data(struct ldc_conn *lc, struct ldc_pkt *lp)
+{
+	struct vio_msg *vm = (struct vio_msg *)lp;
+
+	switch (vm->type) {
+	case VIO_TYPE_CTRL:
+		if ((lp->env & LDC_FRAG_START) == 0 &&
+		    (lp->env & LDC_FRAG_STOP) == 0)
+			return;
+		vdsp_rx_vio_ctrl(lc->lc_sc, vm);
+		break;
+
+	case VIO_TYPE_DATA:
+		if((lp->env & LDC_FRAG_START) == 0)
+			return;
+		vdsp_rx_vio_data(lc->lc_sc, vm);
+		break;
+
+	default:
+		DPRINTF(("Unhandled packet type 0x%02x\n", vm->type));
+		ldc_reset(lc);
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_ctrl(struct vdsp_softc *sc, struct vio_msg *vm)
+{
+	struct vio_msg_tag *tag = (struct vio_msg_tag *)&vm->type;
+
+	switch (tag->stype_env) {
+	case VIO_VER_INFO:
+		vdsp_rx_vio_ver_info(sc, tag);
+		break;
+	case VIO_ATTR_INFO:
+		vdsp_rx_vio_attr_info(sc, tag);
+		break;
+	case VIO_DRING_REG:
+		vdsp_rx_vio_dring_reg(sc, tag);
+		break;
+	case VIO_RDX:
+		vdsp_rx_vio_rdx(sc, tag);
+		break;
+	default:
+		DPRINTF(("CTRL/0x%02x/0x%04x\n", tag->stype, tag->stype_env));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_ver_info(struct vdsp_softc *sc, struct vio_msg_tag *tag)
+{
+	struct vio_ver_info *vi = (struct vio_ver_info *)tag;
+
+	switch (vi->tag.stype) {
+	case VIO_SUBTYPE_INFO:
+		DPRINTF(("CTRL/INFO/VER_INFO\n"));
+
+		/* Make sure we're talking to a virtual disk. */
+		if (vi->dev_class != VDEV_DISK) {
+			/* Huh, we're not talking to a disk device? */
+			printf("%s: peer is not a disk device\n",
+			    sc->sc_dv.dv_xname);
+			vi->tag.stype = VIO_SUBTYPE_NACK;
+			vi->major = 0;
+			vdsp_sendmsg(sc, vi, sizeof(*vi));
+			return;
+		}
+
+		if (vi->major != VDSK_MAJOR) {
+			vi->tag.stype = VIO_SUBTYPE_NACK;
+			vi->major = VDSK_MAJOR;
+			vi->minor = VDSK_MINOR;
+			vdsp_sendmsg(sc, vi, sizeof(*vi));
+			return;
+		}
+
+		vi->tag.stype = VIO_SUBTYPE_ACK;
+		vi->tag.sid = sc->sc_local_sid;
+		vi->minor = VDSK_MINOR;
+		vdsp_sendmsg(sc, vi, sizeof(*vi));
+		sc->sc_vio_state |= VIO_RCV_VER_INFO;
+		break;
+
+	case VIO_SUBTYPE_ACK:
+		DPRINTF(("CTRL/ACK/VER_INFO\n"));
+		break;
+
+	default:
+		DPRINTF(("CTRL/0x%02x/VER_INFO\n", vi->tag.stype));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_attr_info(struct vdsp_softc *sc, struct vio_msg_tag *tag)
+{
+	struct vd_attr_info *ai = (struct vd_attr_info *)tag;
+
+	switch (ai->tag.stype) {
+	case VIO_SUBTYPE_INFO:
+		DPRINTF(("CTRL/INFO/ATTR_INFO\n"));
+
+		if (ai->xfer_mode != VIO_DESC_MODE &&
+		    ai->xfer_mode != VIO_DRING_MODE) {
+			printf("%s: peer uses unsupported xfer mode 0x%02x\n",
+			    sc->sc_dv.dv_xname, ai->xfer_mode);
+			ai->tag.stype = VIO_SUBTYPE_NACK;
+			vdsp_sendmsg(sc, ai, sizeof(*ai));
+			return;
+		}
+		sc->sc_xfer_mode = ai->xfer_mode;
+		sc->sc_vio_state |= VIO_RCV_ATTR_INFO;
+
+		workq_add_task(NULL, 0, vdsp_open, sc, NULL);
+		break;
+
+	case VIO_SUBTYPE_ACK:
+		DPRINTF(("CTRL/ACK/ATTR_INFO\n"));
+		break;
+
+	default:
+		DPRINTF(("CTRL/0x%02x/ATTR_INFO\n", ai->tag.stype));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_dring_reg(struct vdsp_softc *sc, struct vio_msg_tag *tag)
+{
+	struct vio_dring_reg *dr = (struct vio_dring_reg *)tag;
+
+	switch (dr->tag.stype) {
+	case VIO_SUBTYPE_INFO:
+		DPRINTF(("CTRL/INFO/DRING_REG\n"));
+
+		if (dr->num_descriptors > VDSK_MAX_DESCRIPTORS ||
+		    dr->descriptor_size > sizeof(struct vd_desc) ||
+		    dr->ncookies > 1) {
+			dr->tag.stype = VIO_SUBTYPE_NACK;
+			vdsp_sendmsg(sc, dr, sizeof(*dr));
+			return;
+		}
+		sc->sc_num_descriptors = dr->num_descriptors;
+		sc->sc_descriptor_size = dr->descriptor_size;
+		sc->sc_dring_cookie = dr->cookie[0];
+		sc->sc_vio_state |= VIO_RCV_DRING_REG;
+
+		workq_add_task(NULL, 0, vdsp_alloc, sc, NULL);
+		break;
+
+	case VIO_SUBTYPE_ACK:
+		DPRINTF(("CTRL/ACK/DRING_REG\n"));
+		break;
+
+	default:
+		DPRINTF(("CTRL/0x%02x/DRING_REG\n", dr->tag.stype));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_rdx(struct vdsp_softc *sc, struct vio_msg_tag *tag)
+{
+	switch(tag->stype) {
+	case VIO_SUBTYPE_INFO:
+		DPRINTF(("CTRL/INFO/RDX\n"));
+
+		tag->stype = VIO_SUBTYPE_ACK;
+		tag->sid = sc->sc_local_sid;
+		vdsp_sendmsg(sc, tag, sizeof(*tag));
+		sc->sc_vio_state |= VIO_RCV_RDX;
+		break;
+
+	case VIO_SUBTYPE_ACK:
+		DPRINTF(("CTRL/ACK/RDX\n"));
+		break;
+
+	default:
+		DPRINTF(("CTRL/0x%02x/RDX (VIO)\n", tag->stype));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_data(struct vdsp_softc *sc, struct vio_msg *vm)
+{
+	struct vio_msg_tag *tag = (struct vio_msg_tag *)&vm->type;
+
+	if (!ISSET(sc->sc_vio_state, VIO_RCV_RDX)) {
+		DPRINTF(("Spurious DATA/0x%02x/0x%04x\n", tag->stype,
+		    tag->stype_env));
+		return;
+	}
+
+	switch(tag->stype_env) {
+	case VIO_DESC_DATA:
+		vdsp_rx_vio_desc_data(sc, tag);
+		break;
+
+	case VIO_DRING_DATA:
+		vdsp_rx_vio_dring_data(sc, tag);
+		break;
+
+	default:
+		DPRINTF(("DATA/0x%02x/0x%04x\n", tag->stype, tag->stype_env));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_dring_data(struct vdsp_softc *sc, struct vio_msg_tag *tag)
+{
+	struct vio_dring_msg *dm = (struct vio_dring_msg *)tag;
+	struct vd_desc *vd;
+	paddr_t pa, offset;
+	psize_t nbytes;
+	int err;
+
+	switch(tag->stype) {
+	case VIO_SUBTYPE_INFO:
+		DPRINTF(("DATA/INFO/DRING_DATA\n"));
+
+		if (dm->dring_ident != sc->sc_dring_ident ||
+		    dm->start_idx >= sc->sc_num_descriptors) {
+			dm->tag.stype = VIO_SUBTYPE_NACK;
+			vdsp_sendmsg(sc, dm, sizeof(*dm));
+			return;
+		}
+
+		vd = &sc->sc_vd[dm->start_idx];
+		pmap_extract(pmap_kernel(), (vaddr_t)vd, &pa);
+		offset = dm->start_idx * sc->sc_descriptor_size;
+		err = hv_ldc_copy(sc->sc_lc.lc_id, LDC_COPY_IN,
+		    sc->sc_dring_cookie.addr | offset, pa,
+		    sc->sc_descriptor_size, &nbytes);
+		if (err != H_EOK) {
+			printf("hv_ldc_copy %d\n", err);
+			return;
+		}
+
+		switch (vd->operation) {
+		case VD_OP_BREAD:
+			workq_add_task(NULL, 0, vdsp_read_dring, sc, vd);
+			break;
+		case VD_OP_BWRITE:
+			workq_add_task(NULL, 0, vdsp_write_dring, sc, vd);
+			break;
+		case VD_OP_FLUSH:
+			workq_add_task(NULL, 0, vdsp_flush_dring, sc, vd);
+			break;
+		default:
+			printf("%s: unsupported operation 0x%02x\n",
+			    sc->sc_dv.dv_xname, vd->operation);
+			break;
+		}
+		break;
+
+	case VIO_SUBTYPE_ACK:
+		DPRINTF(("DATA/ACK/DRING_DATA\n"));
+		break;
+
+	case VIO_SUBTYPE_NACK:
+		DPRINTF(("DATA/NACK/DRING_DATA\n"));
+		break;
+
+	default:
+		DPRINTF(("DATA/0x%02x/DRING_DATA\n", tag->stype));
+		break;
+	}
+}
+
+void
+vdsp_rx_vio_desc_data(struct vdsp_softc *sc, struct vio_msg_tag *tag)
+{
+	struct vdsk_desc_msg *dm = (struct vdsk_desc_msg *)tag;
+
+	switch(tag->stype) {
+	case VIO_SUBTYPE_INFO:
+		DPRINTF(("DATA/INFO/DESC_DATA\n"));
+
+		switch (dm->operation) {
+		case VD_OP_BREAD:
+			workq_add_task(NULL, 0, vdsp_read, sc, dm);
+			break;
+		default:
+			printf("%s: unsupported operation 0x%02x\n",
+			    sc->sc_dv.dv_xname, dm->operation);
+			break;
+		}
+		break;
+
+	case VIO_SUBTYPE_ACK:
+		DPRINTF(("DATA/ACK/DESC_DATA\n"));
+		break;
+
+	case VIO_SUBTYPE_NACK:
+		DPRINTF(("DATA/NACK/DESC_DATA\n"));
+		break;
+
+	default:
+		DPRINTF(("DATA/0x%02x/DESC_DATA\n", tag->stype));
+		break;
+	}
+}
+
+void
+vdsp_ldc_reset(struct ldc_conn *lc)
+{
+	struct vdsp_softc *sc = lc->lc_sc;
+
+	sc->sc_vio_state = 0;
+	if (sc->sc_vd) {
+		free(sc->sc_vd, M_DEVBUF);
+		sc->sc_vd = NULL;
+	}
+
+}
+
+void
+vdsp_ldc_start(struct ldc_conn *lc)
+{
+	/* The vDisk client is supposed to initiate the handshake. */
+}
+
+void
+vdsp_sendmsg(struct vdsp_softc *sc, void *msg, size_t len)
+{
+	struct ldc_conn *lc = &sc->sc_lc;
+	struct ldc_pkt *lp;
+	uint64_t tx_head, tx_tail, tx_state;
+	uint8_t *p = msg;
+	int err;
+
+	err = hv_ldc_tx_get_state(lc->lc_id, &tx_head, &tx_tail, &tx_state);
+	if (err != H_EOK)
+		return;
+
+	while (len > 0) {
+		lp = (struct ldc_pkt *)(lc->lc_txq->lq_va + tx_tail);
+		bzero(lp, sizeof(struct ldc_pkt));
+		lp->type = LDC_DATA;
+		lp->stype = LDC_INFO;
+		lp->env = min(len, LDC_PKT_PAYLOAD);
+		if (p == msg)
+			lp->env |= LDC_FRAG_START;
+		if (len <= LDC_PKT_PAYLOAD)
+			lp->env |= LDC_FRAG_STOP;
+		lp->seqid = lc->lc_tx_seqid++;
+		bcopy(p, &lp->major, min(len, LDC_PKT_PAYLOAD));
+
+		tx_tail += sizeof(*lp);
+		tx_tail &= ((lc->lc_txq->lq_nentries * sizeof(*lp)) - 1);
+		err = hv_ldc_tx_set_qtail(lc->lc_id, tx_tail);
+		if (err != H_EOK)
+			printf("%s: hv_ldc_tx_set_qtail: %d\n", __func__, err);
+		p += min(len, LDC_PKT_PAYLOAD);
+		len -= min(len, LDC_PKT_PAYLOAD);
+	}
+}
+
+void
+vdsp_mountroot(void *arg)
+{
+	struct vdsp_softc *sc = arg;
+	struct ldc_conn *lc = &sc->sc_lc;
+	int err;
+
+	err = hv_ldc_tx_qconf(lc->lc_id,
+	    lc->lc_txq->lq_map->dm_segs[0].ds_addr, lc->lc_txq->lq_nentries);
+	if (err != H_EOK)
+		printf("hv_ldc_tx_qconf %d\n", err);
+
+	err = hv_ldc_rx_qconf(lc->lc_id,
+	    lc->lc_rxq->lq_map->dm_segs[0].ds_addr, lc->lc_rxq->lq_nentries);
+	if (err != H_EOK)
+		printf("hv_ldc_rx_qconf %d\n", err);
+
+	cbus_intr_setenabled(sc->sc_tx_sysino, INTR_ENABLED);
+	cbus_intr_setenabled(sc->sc_rx_sysino, INTR_ENABLED);
+}
+
+void
+vdsp_open(void *arg1, void *arg2)
+{
+	struct vdsp_softc *sc = arg1;
+	struct proc *p = curproc;
+	struct vd_attr_info ai;
+
+	if (sc->sc_vp == NULL) {
+		struct nameidata nd;
+		struct vattr va;
+		const char *name;
+		int error;
+
+		name = mdesc_get_prop_str(sc->sc_idx, "vds-block-device");
+		if (name == NULL)
+			return;
+
+		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, name, p);
+		error = vn_open(&nd, FREAD, 0);
+		if (error) {
+			printf("VOP_OPEN: %s, %d\n", name, error);
+			return;
+		}
+
+		error = VOP_GETATTR(nd.ni_vp, &va, p->p_ucred, p);
+		if (error)
+			printf("VOP_GETATTR: %s, %d\n", name, error);
+		sc->sc_vdisk_block_size = DEV_BSIZE;
+		sc->sc_vdisk_size = va.va_size / DEV_BSIZE;
+
+		VOP_UNLOCK(nd.ni_vp, 0, p);
+		sc->sc_vp = nd.ni_vp;
+	}
+
+	bzero(&ai, sizeof(ai));
+	ai.tag.type = VIO_TYPE_CTRL;
+	ai.tag.stype = VIO_SUBTYPE_ACK;
+	ai.tag.stype_env = VIO_ATTR_INFO;
+	ai.tag.sid = sc->sc_local_sid;
+	ai.xfer_mode = sc->sc_xfer_mode;
+	ai.vdisk_block_size = sc->sc_vdisk_block_size;
+	ai.vdisk_size = sc->sc_vdisk_size;
+	vdsp_sendmsg(sc, &ai, sizeof(ai));
+}
+
+void
+vdsp_alloc(void *arg1, void *arg2)
+{
+	struct vdsp_softc *sc = arg1;
+	struct vio_dring_reg dr;
+
+	KASSERT(sc->sc_num_descriptors <= 1024);
+	sc->sc_vd = malloc(sc->sc_num_descriptors * sizeof(struct vd_desc),
+	    M_WAITOK, M_DEVBUF);
+
+	bzero(&dr, sizeof(dr));
+	dr.tag.type = VIO_TYPE_CTRL;
+	dr.tag.stype = VIO_SUBTYPE_ACK;
+	dr.tag.stype_env = VIO_DRING_REG;
+	dr.tag.sid = sc->sc_local_sid;
+	dr.dring_ident = ++sc->sc_dring_ident;
+	vdsp_sendmsg(sc, &dr, sizeof(dr));
+}
+
+void
+vdsp_read(void *arg1, void *arg2)
+{
+	struct vdsp_softc *sc = arg1;
+	struct ldc_conn *lc = &sc->sc_lc;
+	struct vdsk_desc_msg *dm = arg2;
+	struct proc *p = curproc;
+	struct iovec iov;
+	struct uio uio;
+	caddr_t buf;
+	vaddr_t va;
+	paddr_t pa;
+	uint64_t size, off;
+	psize_t nbytes;
+	int err, i;
+
+	if (sc->sc_vp == NULL)
+		return;
+
+	buf = malloc(dm->size, M_DEVBUF, M_WAITOK);
+
+	iov.iov_base = buf;
+	iov.iov_len = dm->size;
+	uio.uio_iov = &iov;
+	uio.uio_iovcnt = 1;
+	uio.uio_offset = dm->offset * DEV_BSIZE;
+	uio.uio_resid = dm->size;
+	uio.uio_segflg = UIO_SYSSPACE;
+	uio.uio_rw = UIO_READ;
+	uio.uio_procp = p;
+
+	vn_lock(sc->sc_vp, LK_EXCLUSIVE | LK_RETRY, p);
+	dm->status = VOP_READ(sc->sc_vp, &uio, 0, p->p_ucred);
+	VOP_UNLOCK(sc->sc_vp, 0, p);
+
+	if (dm->status == 0) {
+		i = 0;
+		va = (vaddr_t)buf;
+		size = dm->size;
+		off = 0;
+		while (size > 0 && i < dm->ncookies) {
+			pmap_extract(pmap_kernel(), va, &pa);
+			nbytes = min(size, dm->cookie[i].size - off);
+			nbytes = min(nbytes, PAGE_SIZE - (off & PAGE_MASK));
+			err = hv_ldc_copy(lc->lc_id, LDC_COPY_OUT,
+			    dm->cookie[i].addr + off, pa, nbytes, &nbytes);
+			if (err != H_EOK)
+				printf("hv_ldc_copy: %d\n", err);
+			va += nbytes;
+			size -= nbytes;
+			off += nbytes;
+			if (off >= dm->cookie[i].size) {
+				off = 0;
+				i++;
+			}
+		}
+	}
+
+	free(buf, M_DEVBUF);
+
+	/* ACK the descriptor. */
+	dm->tag.stype = VIO_SUBTYPE_ACK;
+	dm->tag.sid = sc->sc_local_sid;
+	vdsp_sendmsg(sc, dm, sizeof(*dm) +
+	    (dm->ncookies - 1) * sizeof(struct ldc_cookie));
+}
+
+void
+vdsp_read_dring(void *arg1, void *arg2)
+{
+	struct vdsp_softc *sc = arg1;
+	struct ldc_conn *lc = &sc->sc_lc;
+	struct vd_desc *vd = arg2;
+	struct vio_dring_msg dm;
+	struct proc *p = curproc;
+	struct iovec iov;
+	struct uio uio;
+	caddr_t buf;
+	vaddr_t va;
+	paddr_t pa, offset;
+	uint64_t size, off;
+	psize_t nbytes;
+	int err, i;
+
+	if (sc->sc_vp == NULL)
+		return;
+
+	buf = malloc(vd->size, M_DEVBUF, M_WAITOK);
+
+	iov.iov_base = buf;
+	iov.iov_len = vd->size;
+	uio.uio_iov = &iov;
+	uio.uio_iovcnt = 1;
+	uio.uio_offset = vd->offset * DEV_BSIZE;
+	uio.uio_resid = vd->size;
+	uio.uio_segflg = UIO_SYSSPACE;
+	uio.uio_rw = UIO_READ;
+	uio.uio_procp = p;
+
+	vn_lock(sc->sc_vp, LK_EXCLUSIVE | LK_RETRY, p);
+	vd->status = VOP_READ(sc->sc_vp, &uio, 0, p->p_ucred);
+	VOP_UNLOCK(sc->sc_vp, 0, p);
+
+	if (vd->status == 0) {
+		i = 0;
+		va = (vaddr_t)buf;
+		size = vd->size;
+		off = 0;
+		while (size > 0 && i < vd->ncookies) {
+			pmap_extract(pmap_kernel(), va, &pa);
+			nbytes = min(size, vd->cookie[i].size - off);
+			nbytes = min(nbytes, PAGE_SIZE - (off & PAGE_MASK));
+			err = hv_ldc_copy(lc->lc_id, LDC_COPY_OUT,
+			    vd->cookie[i].addr + off, pa, nbytes, &nbytes);
+			if (err != H_EOK)
+				printf("hv_ldc_copy: %d\n", err);
+			va += nbytes;
+			size -= nbytes;
+			off += nbytes;
+			if (off >= vd->cookie[i].size) {
+				off = 0;
+				i++;
+			}
+		}
+	}
+
+	free(buf, M_DEVBUF);
+
+	vd->hdr.dstate = VIO_DESC_DONE;
+	pmap_extract(pmap_kernel(), (vaddr_t)vd, &pa);
+	offset = (vd - sc->sc_vd) * sc->sc_descriptor_size;
+	err = hv_ldc_copy(sc->sc_lc.lc_id, LDC_COPY_OUT,
+	    sc->sc_dring_cookie.addr | offset, pa,
+	    sc->sc_descriptor_size, &nbytes);
+	if (err != H_EOK) {
+		printf("hv_ldc_copy %d\n", err);
+		return;
+	}
+
+	/* ACK the descriptor. */
+	bzero(&dm, sizeof(dm));
+	dm.tag.type = VIO_TYPE_DATA;
+	dm.tag.stype = VIO_SUBTYPE_ACK;
+	dm.tag.stype_env = VIO_DRING_DATA;
+	dm.tag.sid = sc->sc_local_sid;
+	dm.dring_ident = sc->sc_dring_ident;
+	vdsp_sendmsg(sc, &dm, sizeof(dm));
+}
+
+void
+vdsp_write_dring(void *arg1, void *arg2)
+{
+	struct vdsp_softc *sc = arg1;
+	struct ldc_conn *lc = &sc->sc_lc;
+	struct vd_desc *vd = arg2;
+	struct vio_dring_msg dm;
+	struct proc *p = curproc;
+	struct iovec iov;
+	struct uio uio;
+	caddr_t buf;
+	vaddr_t va;
+	paddr_t pa, offset;
+	uint64_t size, off;
+	psize_t nbytes;
+	int err, i;
+
+	if (sc->sc_vp == NULL)
+		return;
+
+	buf = malloc(vd->size, M_DEVBUF, M_WAITOK);
+
+	i = 0;
+	va = (vaddr_t)buf;
+	size = vd->size;
+	off = 0;
+	while (size > 0 && i < vd->ncookies) {
+		pmap_extract(pmap_kernel(), va, &pa);
+		nbytes = min(size, vd->cookie[i].size - off);
+		nbytes = min(nbytes, PAGE_SIZE - (off & PAGE_MASK));
+		err = hv_ldc_copy(lc->lc_id, LDC_COPY_IN,
+		    vd->cookie[i].addr + off, pa, nbytes, &nbytes);
+		if (err != H_EOK)
+			printf("hv_ldc_copy: %d\n", err);
+		va += nbytes;
+		size -= nbytes;
+		off += nbytes;
+		if (off >= vd->cookie[i].size) {
+			off = 0;
+			i++;
+		}
+	}
+
+	iov.iov_base = buf;
+	iov.iov_len = vd->size;
+	uio.uio_iov = &iov;
+	uio.uio_iovcnt = 1;
+	uio.uio_offset = vd->offset * DEV_BSIZE;
+	uio.uio_resid = vd->size;
+	uio.uio_segflg = UIO_SYSSPACE;
+	uio.uio_rw = UIO_WRITE;
+	uio.uio_procp = p;
+
+	vn_lock(sc->sc_vp, LK_EXCLUSIVE | LK_RETRY, p);
+	vd->status = VOP_WRITE(sc->sc_vp, &uio, 0, p->p_ucred);
+	VOP_UNLOCK(sc->sc_vp, 0, p);
+
+	free(buf, M_DEVBUF);
+
+	vd->hdr.dstate = VIO_DESC_DONE;
+	pmap_extract(pmap_kernel(), (vaddr_t)vd, &pa);
+	offset = (vd - sc->sc_vd) * sc->sc_descriptor_size;
+	err = hv_ldc_copy(sc->sc_lc.lc_id, LDC_COPY_OUT,
+	    sc->sc_dring_cookie.addr | offset, pa,
+	    sc->sc_descriptor_size, &nbytes);
+	if (err != H_EOK) {
+		printf("hv_ldc_copy %d\n", err);
+		return;
+	}
+
+	/* ACK the descriptor. */
+	bzero(&dm, sizeof(dm));
+	dm.tag.type = VIO_TYPE_DATA;
+	dm.tag.stype = VIO_SUBTYPE_ACK;
+	dm.tag.stype_env = VIO_DRING_DATA;
+	dm.tag.sid = sc->sc_local_sid;
+	dm.dring_ident = sc->sc_dring_ident;
+	vdsp_sendmsg(sc, &dm, sizeof(dm));
+}
+
+void
+vdsp_flush_dring(void *arg1, void *arg2)
+{
+	struct vdsp_softc *sc = arg1;
+	struct vd_desc *vd = arg2;
+	struct vio_dring_msg dm;
+	paddr_t pa, offset;
+	psize_t nbytes;
+	int err;
+
+	if (sc->sc_vp == NULL)
+		return;
+
+	vd->status = 0;
+	vd->hdr.dstate = VIO_DESC_DONE;
+	pmap_extract(pmap_kernel(), (vaddr_t)vd, &pa);
+	offset = (vd - sc->sc_vd) * sc->sc_descriptor_size;
+	err = hv_ldc_copy(sc->sc_lc.lc_id, LDC_COPY_OUT,
+	    sc->sc_dring_cookie.addr | offset, pa,
+	    sc->sc_descriptor_size, &nbytes);
+	if (err != H_EOK) {
+		printf("hv_ldc_copy %d\n", err);
+		return;
+	}
+
+	/* ACK the descriptor. */
+	bzero(&dm, sizeof(dm));
+	dm.tag.type = VIO_TYPE_DATA;
+	dm.tag.stype = VIO_SUBTYPE_ACK;
+	dm.tag.stype_env = VIO_DRING_DATA;
+	dm.tag.sid = sc->sc_local_sid;
+	dm.dring_ident = sc->sc_dring_ident;
+	vdsp_sendmsg(sc, &dm, sizeof(dm));
+}