More minor virtio tweaks

* add some comments about virtio_enqueue_trim
* include mutex.h explicitly
* make VIRTIO_DEBUG == 1 less verbose in vioblk

ok krw@

3 files changed, 40 insertions, 17 deletions

diff --git a/sys/dev/pv/vioblk.c b/sys/dev/pv/vioblk.c
index 82f63ce03f0..64552e3e0ec 100644
--- a/sys/dev/pv/vioblk.c
+++ b/sys/dev/pv/vioblk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vioblk.c,v 1.6 2017/05/30 17:47:11 krw Exp $	*/
+/*	$OpenBSD: vioblk.c,v 1.7 2017/05/30 19:28:09 sf Exp $	*/
 
 /*
  * Copyright (c) 2012 Stefan Fritsch.
@@ -54,6 +54,7 @@
 #include <sys/device.h>
 #include <sys/stat.h>
 #include <sys/buf.h>
+#include <sys/mutex.h>
 #include <dev/pv/virtioreg.h>
 #include <dev/pv/virtiovar.h>
 #include <dev/pv/vioblkreg.h>
@@ -155,11 +156,8 @@ int vioblk_match(struct device *parent, void *match, void *aux)
 	return 0;
 }
 
-#if VIRTIO_DEBUG > 0
-#define DPRINTF(x...) printf(x)
-#else
-#define DPRINTF(x...)		do {} while (0)
-#endif
+#define DNPRINTF(n,x...)				\
+    do { if (VIRTIO_DEBUG >= n) printf(x); } while(0)
 
 void
 vioblk_attach(struct device *parent, struct device *self, void *aux)
@@ -247,7 +245,7 @@ vioblk_attach(struct device *parent, struct device *self, void *aux)
 	sc->sc_link.adapter_buswidth = 2;
 	sc->sc_link.luns = 1;
 	sc->sc_link.adapter_target = 2;
-	DPRINTF("%s: qsize: %d\n", __func__, qsize);
+	DNPRINTF(1, "%s: qsize: %d\n", __func__, qsize);
 	if (features & VIRTIO_BLK_F_RO)
 		sc->sc_link.flags |= SDEV_READONLY;
 
@@ -285,7 +283,7 @@ vioblk_req_get(void *cookie)
 		SLIST_REMOVE_HEAD(&sc->sc_freelist, vr_list);
 	mtx_leave(&sc->sc_vr_mtx);
 
-	DPRINTF("%s: %p\n", __func__, vr);
+	DNPRINTF(2, "%s: %p\n", __func__, vr);
 
 	return vr;
 }
@@ -296,7 +294,7 @@ vioblk_req_put(void *cookie, void *io)
 	struct vioblk_softc *sc = cookie;
 	struct virtio_blk_req *vr = io;
 
-	DPRINTF("%s: %p\n", __func__, vr);
+	DNPRINTF(2, "%s: %p\n", __func__, vr);
 
 	mtx_enter(&sc->sc_vr_mtx);
 	/*
@@ -356,7 +354,7 @@ vioblk_vq_done1(struct vioblk_softc *sc, struct virtio_softc *vsc,
 
 
 	if (vr->vr_status != VIRTIO_BLK_S_OK) {
-		DPRINTF("%s: EIO\n", __func__);
+		DNPRINTF(1, "%s: EIO\n", __func__);
 		xs->error = XS_DRIVER_STUFFUP;
 		xs->resid = xs->datalen;
 	} else {
@@ -695,15 +693,16 @@ vioblk_alloc_reqs(struct vioblk_softc *sc, int qsize)
 			 */
 			vd = &vq->vq_desc[slot];
 			for (r = 0; r < ALLOC_SEGS - 1; r++) {
-				DPRINTF("%s: vd[%d].next = %d should be %d\n",
-				    __func__, r, vd[r].next, (slot + r + 1));
+				DNPRINTF(2, "%s: vd[%d].next = %d should be "
+				    "%d\n", __func__, r, vd[r].next,
+				    (slot + r + 1));
 				if (vd[r].next != (slot + r + 1))
 					return i;
 			}
 			if (r == (ALLOC_SEGS -1) && vd[r].next != 0)
 				return i;
-			DPRINTF("%s: reserved slots are contiguous (good!)\n",
-			    __func__);
+			DNPRINTF(2, "%s: reserved slots are contiguous "
+			    "(good!)\n", __func__);
 		}
 
 		vr->vr_qe_index = slot;
diff --git a/sys/dev/pv/vioscsi.c b/sys/dev/pv/vioscsi.c
index 8e90a73f762..cdd2a5ea3b2 100644
--- a/sys/dev/pv/vioscsi.c
+++ b/sys/dev/pv/vioscsi.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vioscsi.c,v 1.10 2017/05/30 12:47:47 krw Exp $	*/
+/*	$OpenBSD: vioscsi.c,v 1.11 2017/05/30 19:28:09 sf Exp $	*/
 /*
  * Copyright (c) 2013 Google Inc.
  *
@@ -19,6 +19,7 @@
 #include <sys/types.h>
 #include <sys/systm.h>
 #include <sys/device.h>
+#include <sys/mutex.h>
 
 #include <machine/bus.h>
 #include <machine/intr.h>
diff --git a/sys/dev/pv/virtio.c b/sys/dev/pv/virtio.c
index 6dbfb35d2cb..116e1002d09 100644
--- a/sys/dev/pv/virtio.c
+++ b/sys/dev/pv/virtio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: virtio.c,v 1.8 2017/05/30 12:47:47 krw Exp $	*/
+/*	$OpenBSD: virtio.c,v 1.9 2017/05/30 19:28:09 sf Exp $	*/
 /*	$NetBSD: virtio.c,v 1.3 2011/11/02 23:05:52 njoly Exp $	*/
 
 /*
@@ -462,7 +462,7 @@ vq_free_entry(struct virtqueue *vq, struct vq_entry *qe)
  *  - command blocks (in dmamem) should be pre-allocated and mapped
  *  - dmamaps for command blocks should be pre-allocated and loaded
  *  - dmamaps for payload should be pre-allocated
- *      r = virtio_enqueue_prep(sc, vq, &slot);		// allocate a slot
+ *	r = virtio_enqueue_prep(sc, vq, &slot);		// allocate a slot
  *	if (r)		// currently 0 or EAGAIN
  *	  return r;
  *	r = bus_dmamap_load(dmat, dmamap_payload[slot], data, count, ..);
@@ -484,6 +484,26 @@ vq_free_entry(struct virtqueue *vq, struct vq_entry *qe)
  *	virtio_enqueue(sc, vq, slot, dmamap_cmd[slot], 0);
  *	virtio_enqueue(sc, vq, slot, dmamap_payload[slot], iswrite);
  *	virtio_enqueue_commit(sc, vq, slot, 1);
+ *
+ * Alternative usage with statically allocated slots:
+ *	<during initialization>
+ *	// while not out of slots, do
+ *	virtio_enqueue_prep(sc, vq, &slot);		// allocate a slot
+ *	virtio_enqueue_reserve(sc, vq, slot, max_segs);	// reserve all slots
+ *						that may ever be needed
+ *
+ *	<when enqueing a request>
+ *	// Don't call virtio_enqueue_prep()
+ *	bus_dmamap_load(dmat, dmamap_payload[slot], data, count, ..);
+ *	bus_dmamap_sync(dmat, dmamap_cmd[slot],... BUS_DMASYNC_PREWRITE);
+ *	bus_dmamap_sync(dmat, dmamap_payload[slot],...);
+ *	virtio_enqueue_trim(sc, vq, slot, num_segs_needed);
+ *	virtio_enqueue(sc, vq, slot, dmamap_cmd[slot], 0);
+ *	virtio_enqueue(sc, vq, slot, dmamap_payload[slot], iswrite);
+ *	virtio_enqueue_commit(sc, vq, slot, 1);
+ *
+ *	<when dequeuing>
+ *	// don't call virtio_dequeue_commit()
  */
 
 /*
@@ -785,6 +805,9 @@ virtio_dequeue(struct virtio_softc *sc, struct virtqueue *vq,
 /*
  * dequeue_commit: complete dequeue; the slot is recycled for future use.
  *                 if you forget to call this the slot will be leaked.
+ *
+ *                 Don't call this if you use statically allocated slots
+ *                 and virtio_dequeue_trim().
  */
 int
 virtio_dequeue_commit(struct virtqueue *vq, int slot)