Import virtio base, PCI front-end, and net/block/balloon drivers.

Tested on Qemu/KVM, VirtualBox, and BHyVe.

Currently built as modules-only on i386/amd64. Man pages not yet hooked
up, pending review.

Submitted by:	Bryan Venteicher  bryanv at daemoninthecloset dot org
Reviewed by:	bz
MFC after:	4 weeks or so

2 files changed, 610 insertions, 0 deletions

diff --git a/sys/dev/virtio/balloon/virtio_balloon.c b/sys/dev/virtio/balloon/virtio_balloon.c
new file mode 100644
index 0000000..ef7aca9
--- /dev/null
+++ b/sys/dev/virtio/balloon/virtio_balloon.c
@@ -0,0 +1,569 @@
+/*-
+ * Copyright (c) 2011, Bryan Venteicher <bryanv@daemoninthecloset.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice unmodified, this list of conditions, and the following
+ *    disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* Driver for VirtIO memory balloon devices. */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/endian.h>
+#include <sys/kthread.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/sglist.h>
+#include <sys/sysctl.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/queue.h>
+
+#include <vm/vm.h>
+#include <vm/vm_page.h>
+
+#include <machine/bus.h>
+#include <machine/resource.h>
+#include <sys/bus.h>
+#include <sys/rman.h>
+
+#include <dev/virtio/virtio.h>
+#include <dev/virtio/virtqueue.h>
+#include <dev/virtio/balloon/virtio_balloon.h>
+
+#include "virtio_if.h"
+
+struct vtballoon_softc {
+	device_t		 vtballoon_dev;
+	struct mtx		 vtballoon_mtx;
+	uint64_t		 vtballoon_features;
+	uint32_t		 vtballoon_flags;
+#define VTBALLOON_FLAG_DETACH	 0x01
+
+	struct virtqueue	*vtballoon_inflate_vq;
+	struct virtqueue	*vtballoon_deflate_vq;
+
+	uint32_t		 vtballoon_desired_npages;
+	uint32_t		 vtballoon_current_npages;
+	TAILQ_HEAD(,vm_page)	 vtballoon_pages;
+
+	struct proc		*vtballoon_kproc;
+	uint32_t		*vtballoon_page_frames;
+	int			 vtballoon_timeout;
+};
+
+static struct virtio_feature_desc vtballoon_feature_desc[] = {
+	{ VIRTIO_BALLOON_F_MUST_TELL_HOST,	"MustTellHost"	},
+	{ VIRTIO_BALLOON_F_STATS_VQ,		"StatsVq"	},
+
+	{ 0, NULL }
+};
+
+static int	vtballoon_probe(device_t);
+static int	vtballoon_attach(device_t);
+static int	vtballoon_detach(device_t);
+static int	vtballoon_config_change(device_t);
+
+static void	vtballoon_negotiate_features(struct vtballoon_softc *);
+static int	vtballoon_alloc_virtqueues(struct vtballoon_softc *);
+
+static int	vtballoon_vq_intr(void *);
+
+static void	vtballoon_inflate(struct vtballoon_softc *, int);
+static void	vtballoon_deflate(struct vtballoon_softc *, int);
+
+static void	vtballoon_send_page_frames(struct vtballoon_softc *,
+		    struct virtqueue *, int);
+
+static void	vtballoon_pop(struct vtballoon_softc *);
+static void	vtballoon_stop(struct vtballoon_softc *);
+
+static vm_page_t
+		vtballoon_alloc_page(struct vtballoon_softc *);
+static void	vtballoon_free_page(struct vtballoon_softc *, vm_page_t);
+
+static int	vtballoon_sleep(struct vtballoon_softc *);
+static void	vtballoon_thread(void *);
+static void	vtballoon_add_sysctl(struct vtballoon_softc *);
+
+/* Features desired/implemented by this driver. */
+#define VTBALLOON_FEATURES		0
+
+/* Timeout between retries when the balloon needs inflating. */
+#define VTBALLOON_LOWMEM_TIMEOUT	hz
+
+/*
+ * Maximum number of pages we'll request to inflate or deflate
+ * the balloon in one virtqueue request. Both Linux and NetBSD
+ * have settled on 256, doing up to 1MB at a time.
+ */
+#define VTBALLOON_PAGES_PER_REQUEST	256
+
+#define VTBALLOON_MTX(_sc)		&(_sc)->vtballoon_mtx
+#define VTBALLOON_LOCK_INIT(_sc, _name)	mtx_init(VTBALLOON_MTX((_sc)), _name, \
+					    "VirtIO Balloon Lock", MTX_SPIN)
+#define VTBALLOON_LOCK(_sc)		mtx_lock_spin(VTBALLOON_MTX((_sc)))
+#define VTBALLOON_UNLOCK(_sc)		mtx_unlock_spin(VTBALLOON_MTX((_sc)))
+#define VTBALLOON_LOCK_DESTROY(_sc)	mtx_destroy(VTBALLOON_MTX((_sc)))
+
+static device_method_t vtballoon_methods[] = {
+	/* Device methods. */
+	DEVMETHOD(device_probe,		vtballoon_probe),
+	DEVMETHOD(device_attach,	vtballoon_attach),
+	DEVMETHOD(device_detach,	vtballoon_detach),
+
+	/* VirtIO methods. */
+	DEVMETHOD(virtio_config_change, vtballoon_config_change),
+
+	{ 0, 0 }
+};
+
+static driver_t vtballoon_driver = {
+	"vtballoon",
+	vtballoon_methods,
+	sizeof(struct vtballoon_softc)
+};
+static devclass_t vtballoon_devclass;
+
+DRIVER_MODULE(virtio_balloon, virtio_pci, vtballoon_driver,
+    vtballoon_devclass, 0, 0);
+MODULE_VERSION(virtio_balloon, 1);
+MODULE_DEPEND(virtio_balloon, virtio, 1, 1, 1);
+
+static int
+vtballoon_probe(device_t dev)
+{
+
+	if (virtio_get_device_type(dev) != VIRTIO_ID_BALLOON)
+		return (ENXIO);
+
+	device_set_desc(dev, "VirtIO Balloon Adapter");
+
+	return (BUS_PROBE_DEFAULT);
+}
+
+static int
+vtballoon_attach(device_t dev)
+{
+	struct vtballoon_softc *sc;
+	int error;
+
+	sc = device_get_softc(dev);
+	sc->vtballoon_dev = dev;
+
+	VTBALLOON_LOCK_INIT(sc, device_get_nameunit(dev));
+	TAILQ_INIT(&sc->vtballoon_pages);
+
+	vtballoon_add_sysctl(sc);
+
+	virtio_set_feature_desc(dev, vtballoon_feature_desc);
+	vtballoon_negotiate_features(sc);
+
+	sc->vtballoon_page_frames = malloc(VTBALLOON_PAGES_PER_REQUEST *
+	    sizeof(uint32_t), M_DEVBUF, M_NOWAIT | M_ZERO);
+	if (sc->vtballoon_page_frames == NULL) {
+		error = ENOMEM;
+		device_printf(dev,
+		    "cannot allocate page frame request array\n");
+		goto fail;
+	}
+
+	error = vtballoon_alloc_virtqueues(sc);
+	if (error) {
+		device_printf(dev, "cannot allocate virtqueues\n");
+		goto fail;
+	}
+
+	error = virtio_setup_intr(dev, INTR_TYPE_MISC);
+	if (error) {
+		device_printf(dev, "cannot setup virtqueue interrupts\n");
+		goto fail;
+	}
+
+	error = kproc_create(vtballoon_thread, sc, &sc->vtballoon_kproc,
+	    0, 0, "virtio_balloon");
+	if (error) {
+		device_printf(dev, "cannot create balloon kproc\n");
+		goto fail;
+	}
+
+	virtqueue_enable_intr(sc->vtballoon_inflate_vq);
+	virtqueue_enable_intr(sc->vtballoon_deflate_vq);
+
+fail:
+	if (error)
+		vtballoon_detach(dev);
+
+	return (error);
+}
+
+static int
+vtballoon_detach(device_t dev)
+{
+	struct vtballoon_softc *sc;
+
+	sc = device_get_softc(dev);
+
+	if (sc->vtballoon_kproc != NULL) {
+		VTBALLOON_LOCK(sc);
+		sc->vtballoon_flags |= VTBALLOON_FLAG_DETACH;
+		wakeup_one(sc);
+		msleep_spin(sc->vtballoon_kproc, VTBALLOON_MTX(sc),
+		    "vtbdth", 0);
+		VTBALLOON_UNLOCK(sc);
+
+		sc->vtballoon_kproc = NULL;
+	}
+
+	if (device_is_attached(dev)) {
+		vtballoon_pop(sc);
+		vtballoon_stop(sc);
+	}
+
+	if (sc->vtballoon_page_frames != NULL) {
+		free(sc->vtballoon_page_frames, M_DEVBUF);
+		sc->vtballoon_page_frames = NULL;
+	}
+
+	VTBALLOON_LOCK_DESTROY(sc);
+
+	return (0);
+}
+
+static int
+vtballoon_config_change(device_t dev)
+{
+	struct vtballoon_softc *sc;
+
+	sc = device_get_softc(dev);
+
+	VTBALLOON_LOCK(sc);
+	wakeup_one(sc);
+	VTBALLOON_UNLOCK(sc);
+
+	return (1);
+}
+
+static void
+vtballoon_negotiate_features(struct vtballoon_softc *sc)
+{
+	device_t dev;
+	uint64_t features;
+
+	dev = sc->vtballoon_dev;
+	features = virtio_negotiate_features(dev, VTBALLOON_FEATURES);
+	sc->vtballoon_features = features;
+}
+
+static int
+vtballoon_alloc_virtqueues(struct vtballoon_softc *sc)
+{
+	device_t dev;
+	struct vq_alloc_info vq_info[2];
+	int nvqs;
+
+	dev = sc->vtballoon_dev;
+	nvqs = 2;
+
+	VQ_ALLOC_INFO_INIT(&vq_info[0], 0, vtballoon_vq_intr, sc,
+	    &sc->vtballoon_inflate_vq, "%s inflate", device_get_nameunit(dev));
+
+	VQ_ALLOC_INFO_INIT(&vq_info[1], 0, vtballoon_vq_intr, sc,
+	    &sc->vtballoon_deflate_vq, "%s deflate", device_get_nameunit(dev));
+
+	return (virtio_alloc_virtqueues(dev, 0, nvqs, vq_info));
+}
+
+static int
+vtballoon_vq_intr(void *xsc)
+{
+	struct vtballoon_softc *sc;
+
+	sc = xsc;
+
+	VTBALLOON_LOCK(sc);
+	wakeup_one(sc);
+	VTBALLOON_UNLOCK(sc);
+
+	return (1);
+}
+
+static void
+vtballoon_inflate(struct vtballoon_softc *sc, int npages)
+{
+	struct virtqueue *vq;
+	vm_page_t m;
+	int i;
+
+	vq = sc->vtballoon_inflate_vq;
+	m = NULL;
+
+	if (npages > VTBALLOON_PAGES_PER_REQUEST)
+		npages = VTBALLOON_PAGES_PER_REQUEST;
+	KASSERT(npages > 0, ("balloon doesn't need inflating?"));
+
+	for (i = 0; i < npages; i++) {
+		if ((m = vtballoon_alloc_page(sc)) == NULL)
+			break;
+
+		sc->vtballoon_page_frames[i] =
+		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
+
+		KASSERT(m->queue == PQ_NONE, ("allocated page on queue"));
+		TAILQ_INSERT_TAIL(&sc->vtballoon_pages, m, pageq);
+	}
+
+	if (i > 0)
+		vtballoon_send_page_frames(sc, vq, i);
+
+	if (m == NULL)
+		sc->vtballoon_timeout = VTBALLOON_LOWMEM_TIMEOUT;
+}
+
+static void
+vtballoon_deflate(struct vtballoon_softc *sc, int npages)
+{
+	TAILQ_HEAD(, vm_page) free_pages;
+	struct virtqueue *vq;
+	vm_page_t m;
+	int i;
+
+	vq = sc->vtballoon_deflate_vq;
+	TAILQ_INIT(&free_pages);
+
+	if (npages > VTBALLOON_PAGES_PER_REQUEST)
+		npages = VTBALLOON_PAGES_PER_REQUEST;
+	KASSERT(npages > 0, ("balloon doesn't need deflating?"));
+
+	for (i = 0; i < npages; i++) {
+		m = TAILQ_FIRST(&sc->vtballoon_pages);
+		KASSERT(m != NULL, ("no more pages to deflate"));
+
+		sc->vtballoon_page_frames[i] =
+		    VM_PAGE_TO_PHYS(m) >> VIRTIO_BALLOON_PFN_SHIFT;
+
+		TAILQ_REMOVE(&sc->vtballoon_pages, m, pageq);
+		TAILQ_INSERT_TAIL(&free_pages, m, pageq);
+	}
+
+	if (i > 0) {
+		/* Always tell host first before freeing the pages. */
+		vtballoon_send_page_frames(sc, vq, i);
+
+		while ((m = TAILQ_FIRST(&free_pages)) != NULL) {
+			TAILQ_REMOVE(&free_pages, m, pageq);
+			vtballoon_free_page(sc, m);
+		}
+	}
+
+	KASSERT((TAILQ_EMPTY(&sc->vtballoon_pages) &&
+	    sc->vtballoon_current_npages == 0) ||
+	    (!TAILQ_EMPTY(&sc->vtballoon_pages) &&
+	    sc->vtballoon_current_npages != 0), ("balloon empty?"));
+}
+
+static void
+vtballoon_send_page_frames(struct vtballoon_softc *sc, struct virtqueue *vq,
+    int npages)
+{
+	struct sglist sg;
+	struct sglist_seg segs[1];
+	void *c;
+	int error;
+
+	sglist_init(&sg, 1, segs);
+
+	error = sglist_append(&sg, sc->vtballoon_page_frames,
+	    npages * sizeof(uint32_t));
+	KASSERT(error == 0, ("error adding page frames to sglist"));
+
+	error = virtqueue_enqueue(vq, vq, &sg, 1, 0);
+	KASSERT(error == 0, ("error enqueuing page frames to virtqueue"));
+
+	/*
+	 * Inflate and deflate operations are done synchronously. The
+	 * interrupt handler will wake us up.
+	 */
+	VTBALLOON_LOCK(sc);
+	virtqueue_notify(vq);
+
+	while ((c = virtqueue_dequeue(vq, NULL)) == NULL)
+		msleep_spin(sc, VTBALLOON_MTX(sc), "vtbspf", 0);
+	VTBALLOON_UNLOCK(sc);
+
+	KASSERT(c == vq, ("unexpected balloon operation response"));
+}
+
+static void
+vtballoon_pop(struct vtballoon_softc *sc)
+{
+
+	while (!TAILQ_EMPTY(&sc->vtballoon_pages))
+		vtballoon_deflate(sc, sc->vtballoon_current_npages);
+}
+
+static void
+vtballoon_stop(struct vtballoon_softc *sc)
+{
+
+	virtqueue_disable_intr(sc->vtballoon_inflate_vq);
+	virtqueue_disable_intr(sc->vtballoon_deflate_vq);
+
+	virtio_stop(sc->vtballoon_dev);
+}
+
+static vm_page_t
+vtballoon_alloc_page(struct vtballoon_softc *sc)
+{
+	vm_page_t m;
+
+	m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_WIRED |
+	    VM_ALLOC_NOOBJ);
+	if (m != NULL)
+		sc->vtballoon_current_npages++;
+
+	return (m);
+}
+
+static void
+vtballoon_free_page(struct vtballoon_softc *sc, vm_page_t m)
+{
+
+	vm_page_unwire(m, 0);
+	vm_page_free(m);
+	sc->vtballoon_current_npages--;
+}
+
+static uint32_t
+vtballoon_desired_size(struct vtballoon_softc *sc)
+{
+	uint32_t desired;
+
+	desired = virtio_read_dev_config_4(sc->vtballoon_dev,
+	    offsetof(struct virtio_balloon_config, num_pages));
+
+	return (le32toh(desired));
+}
+
+static void
+vtballoon_update_size(struct vtballoon_softc *sc)
+{
+
+	virtio_write_dev_config_4(sc->vtballoon_dev,
+	    offsetof(struct virtio_balloon_config, actual),
+	    htole32(sc->vtballoon_current_npages));
+
+}
+
+static int
+vtballoon_sleep(struct vtballoon_softc *sc)
+{
+	int rc, timeout;
+	uint32_t current, desired;
+
+	rc = 0;
+	current = sc->vtballoon_current_npages;
+
+	VTBALLOON_LOCK(sc);
+	for (;;) {
+		if (sc->vtballoon_flags & VTBALLOON_FLAG_DETACH) {
+			rc = 1;
+			break;
+		}
+
+		desired = vtballoon_desired_size(sc);
+		sc->vtballoon_desired_npages = desired;
+
+		/*
+		 * If given, use non-zero timeout on the first time through
+		 * the loop. On subsequent times, timeout will be zero so
+		 * we will reevaluate the desired size of the balloon and
+		 * break out to retry if needed.
+		 */
+		timeout = sc->vtballoon_timeout;
+		sc->vtballoon_timeout = 0;
+
+		if (current > desired)
+			break;
+		if (current < desired && timeout == 0)
+			break;
+
+		msleep_spin(sc, VTBALLOON_MTX(sc), "vtbslp", timeout);
+	}
+	VTBALLOON_UNLOCK(sc);
+
+	return (rc);
+}
+
+static void
+vtballoon_thread(void *xsc)
+{
+	struct vtballoon_softc *sc;
+	uint32_t current, desired;
+
+	sc = xsc;
+
+	for (;;) {
+		if (vtballoon_sleep(sc) != 0)
+			break;
+
+		current = sc->vtballoon_current_npages;
+		desired = sc->vtballoon_desired_npages;
+
+		if (desired != current) {
+			if (desired > current)
+				vtballoon_inflate(sc, desired - current);
+			else
+				vtballoon_deflate(sc, current - desired);
+
+			vtballoon_update_size(sc);
+		}
+	}
+
+	kproc_exit(0);
+}
+
+static void
+vtballoon_add_sysctl(struct vtballoon_softc *sc)
+{
+	device_t dev;
+	struct sysctl_ctx_list *ctx;
+	struct sysctl_oid *tree;
+	struct sysctl_oid_list *child;
+
+	dev = sc->vtballoon_dev;
+	ctx = device_get_sysctl_ctx(dev);
+	tree = device_get_sysctl_tree(dev);
+	child = SYSCTL_CHILDREN(tree);
+
+	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "desired",
+	    CTLFLAG_RD, &sc->vtballoon_desired_npages, sizeof(uint32_t),
+	    "Desired balloon size in pages");
+
+	SYSCTL_ADD_UINT(ctx, child, OID_AUTO, "current",
+	    CTLFLAG_RD, &sc->vtballoon_current_npages, sizeof(uint32_t),
+	    "Current balloon size in pages");
+}
diff --git a/sys/dev/virtio/balloon/virtio_balloon.h b/sys/dev/virtio/balloon/virtio_balloon.h
new file mode 100644
index 0000000..cea84ba
--- /dev/null
+++ b/sys/dev/virtio/balloon/virtio_balloon.h
@@ -0,0 +1,41 @@
+/*
+ * This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _VIRTIO_BALLOON_H
+#define _VIRTIO_BALLOON_H
+
+#include <sys/types.h>
+
+/* Feature bits. */
+#define VIRTIO_BALLOON_F_MUST_TELL_HOST	0x1 /* Tell before reclaiming pages */
+#define VIRTIO_BALLOON_F_STATS_VQ	0x2 /* Memory stats virtqueue */
+
+/* Size of a PFN in the balloon interface. */
+#define VIRTIO_BALLOON_PFN_SHIFT 12
+
+struct virtio_balloon_config {
+	/* Number of pages host wants Guest to give up. */
+	uint32_t num_pages;
+
+	/* Number of pages we've actually got in balloon. */
+	uint32_t actual;
+};
+
+#define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
+#define VIRTIO_BALLOON_S_SWAP_OUT 1   /* Amount of memory swapped out */
+#define VIRTIO_BALLOON_S_MAJFLT   2   /* Number of major faults */
+#define VIRTIO_BALLOON_S_MINFLT   3   /* Number of minor faults */
+#define VIRTIO_BALLOON_S_MEMFREE  4   /* Total amount of free memory */
+#define VIRTIO_BALLOON_S_MEMTOT   5   /* Total amount of memory */
+#define VIRTIO_BALLOON_S_NR       6
+
+struct virtio_balloon_stat {
+	uint16_t tag;
+	uint64_t val;
+} __packed;
+
+#endif /* _VIRTIO_BALLOON_H */