different transports (in our case, virtio).

This is the implementation of (most of) the original
9p2000 protocol, without the .u or the .l extensions.

How to use:
1. Make sure kernel is compiled with:
    CONFIG_NET_9P=y
    CONFIG_NET_9P_VIRTIO=y
    CONFIG_NET_9P_DEBUG=y (At least until code is stable)
    CONFIG_9P_FS=y

2. Start KVM with '--virtio-9p <dirname>'. What happens now is that
a virtio transport with the name 'kvm_9p' is created. The server side
of the transport maps dirname to the root of the file system.

3. Within the guest, mount the fs:
mount -t 9p -otrans=virtio kvm_9p <local_dir> -oversion=9p2000
This will mount the 9p server to local_dir.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 tools/kvm/Makefile                     |    1 +
 tools/kvm/include/kvm/ioport.h         |    2 +
 tools/kvm/include/kvm/virtio-9p.h      |    8 +
 tools/kvm/include/kvm/virtio-pci-dev.h |    1 +
 tools/kvm/kvm-run.c                    |   13 +
 tools/kvm/virtio/9p.c                  |  667 ++++++++++++++++++++++++++++++++
 6 files changed, 692 insertions(+), 0 deletions(-)
 create mode 100644 tools/kvm/include/kvm/virtio-9p.h
 create mode 100644 tools/kvm/virtio/9p.c

diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
index 30f0f61..8a10647 100644
--- a/tools/kvm/Makefile
+++ b/tools/kvm/Makefile
@@ -47,6 +47,7 @@ OBJS    += threadpool.o
 OBJS    += irq.o
 OBJS    += ../../lib/rbtree.o
 OBJS    += util/rbtree-interval.o
+OBJS    += virtio/9p.o
 
 FLAGS_BFD=$(CFLAGS) -lbfd
 has_bfd := $(call try-cc,$(SOURCE_BFD),$(FLAGS_BFD))
diff --git a/tools/kvm/include/kvm/ioport.h b/tools/kvm/include/kvm/ioport.h
index b9bbc3d..218530c 100644
--- a/tools/kvm/include/kvm/ioport.h
+++ b/tools/kvm/include/kvm/ioport.h
@@ -7,6 +7,8 @@
 
 /* some ports we reserve for own use */
 #define IOPORT_DBG			0xe0
+#define IOPORT_VIRTIO_P9		0xb200	/* Virtio 9P device */
+#define IOPORT_VIRTIO_P9_SIZE		256
 #define IOPORT_VIRTIO_BLK		0xc200	/* Virtio block device */
 #define IOPORT_VIRTIO_BLK_SIZE		0x200
 #define IOPORT_VIRTIO_CONSOLE		0xd200	/* Virtio console device */
diff --git a/tools/kvm/include/kvm/virtio-9p.h b/tools/kvm/include/kvm/virtio-9p.h
new file mode 100644
index 0000000..9052830
--- /dev/null
+++ b/tools/kvm/include/kvm/virtio-9p.h
@@ -0,0 +1,8 @@
+#ifndef KVM__VIRTIO_9P_H
+#define KVM__VIRTIO_9P_H
+
+struct kvm;
+
+void virtio_9p__init(struct kvm *kvm, const char *root);
+
+#endif
diff --git a/tools/kvm/include/kvm/virtio-pci-dev.h b/tools/kvm/include/kvm/virtio-pci-dev.h
index fa8328d..1b7862e 100644
--- a/tools/kvm/include/kvm/virtio-pci-dev.h
+++ b/tools/kvm/include/kvm/virtio-pci-dev.h
@@ -12,6 +12,7 @@
 #define PCI_DEVICE_ID_VIRTIO_BLK		0x1001
 #define PCI_DEVICE_ID_VIRTIO_CONSOLE		0x1003
 #define PCI_DEVICE_ID_VIRTIO_RNG		0x1004
+#define PCI_DEVICE_ID_VIRTIO_P9			0x1009
 
 #define PCI_VENDOR_ID_REDHAT_QUMRANET		0x1af4
 #define PCI_SUBSYSTEM_VENDOR_ID_REDHAT_QUMRANET	0x1af4
diff --git a/tools/kvm/kvm-run.c b/tools/kvm/kvm-run.c
index 63181bf..aa7ee0a 100644
--- a/tools/kvm/kvm-run.c
+++ b/tools/kvm/kvm-run.c
@@ -27,6 +27,7 @@
 #include <kvm/threadpool.h>
 #include <kvm/barrier.h>
 #include <kvm/symbol.h>
+#include <kvm/virtio-9p.h>
 
 /* header files for gitish interface  */
 #include <kvm/kvm-run.h>
@@ -62,6 +63,7 @@ static const char *network;
 static const char *host_ip_addr;
 static const char *guest_mac;
 static const char *script;
+static const char *virtio_9p_dir;
 static bool single_step;
 static bool readonly_image[MAX_DISK_IMAGES];
 static bool virtio_rng;
@@ -107,6 +109,8 @@ static const struct option options[] = {
 	OPT_BOOLEAN('\0', "rng", &virtio_rng,
 			"Enable virtio Random Number Generator"),
 	OPT_STRING('\0', "kvm-dev", &kvm_dev, "kvm-dev", "KVM device file"),
+	OPT_STRING('\0', "virtio-9p", &virtio_9p_dir, "root dir",
+			"Enable 9p over virtio"),
 
 	OPT_GROUP("Kernel options:"),
 	OPT_STRING('k', "kernel", &kernel_filename, "kernel",
@@ -473,6 +477,15 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 	if (!script)
 		script = DEFAULT_SCRIPT;
 
+	if (virtio_9p_dir) {
+		char tmp[PATH_MAX];
+
+		if (realpath(virtio_9p_dir, tmp))
+			virtio_9p__init(kvm, tmp);
+		else
+			die("Failed resolving 9p path");
+	}
+
 	symbol__init(vmlinux_filename);
 
 	term_init();
diff --git a/tools/kvm/virtio/9p.c b/tools/kvm/virtio/9p.c
new file mode 100644
index 0000000..56ecd8e
--- /dev/null
+++ b/tools/kvm/virtio/9p.c
@@ -0,0 +1,667 @@
+#include "kvm/virtio-9p.h"
+#include "kvm/virtio-pci-dev.h"
+#include "kvm/virtio.h"
+#include "kvm/ioport.h"
+#include "kvm/mutex.h"
+#include "kvm/util.h"
+#include "kvm/kvm.h"
+#include "kvm/pci.h"
+#include "kvm/threadpool.h"
+#include "kvm/irq.h"
+
+#include <linux/virtio_ring.h>
+#include <linux/virtio_9p.h>
+#include <net/9p/9p.h>
+
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <pthread.h>
+#include <dirent.h>
+
+#define NUM_VIRT_QUEUES		1
+#define VIRTIO_P9_QUEUE_SIZE	128
+#define	VIRTIO_P9_TAG		"kvm_9p"
+#define VIRTIO_P9_HDR_LEN	(sizeof(u32)+sizeof(u8)+sizeof(u16))
+#define VIRTIO_P9_MAX_FID	128
+#define VIRTIO_P9_VERSION	"9P2000"
+
+struct p9_msg {
+	u32			size;
+	u8			cmd;
+	u16			tag;
+	u8			msg[0];
+} __attribute__((packed));
+
+struct p9_fid {
+	u32			fid;
+	u8			is_dir;
+	char			abs_path[PATH_MAX];
+	char			*path;
+	DIR			*dir;
+	int			fd;
+};
+
+static struct pci_device_header virtio_p9_pci_device = {
+	.vendor_id		= PCI_VENDOR_ID_REDHAT_QUMRANET,
+	.device_id		= PCI_DEVICE_ID_VIRTIO_P9,
+	.header_type		= PCI_HEADER_TYPE_NORMAL,
+	.revision_id		= 0,
+	.class			= 0x010000,
+	.subsys_vendor_id	= PCI_SUBSYSTEM_VENDOR_ID_REDHAT_QUMRANET,
+	.subsys_id		= VIRTIO_ID_9P,
+	.bar[0]			= IOPORT_VIRTIO_P9 | PCI_BASE_ADDRESS_SPACE_IO,
+};
+
+struct p9_dev {
+	u8			status;
+	u8			isr;
+	u16			config_vector;
+	u32			features;
+	struct virtio_9p_config	*config;
+
+	/* virtio queue */
+	u16			queue_selector;
+	struct virt_queue	vqs[NUM_VIRT_QUEUES];
+	void			*jobs[NUM_VIRT_QUEUES];
+
+	struct p9_fid		fids[VIRTIO_P9_MAX_FID];
+	char			root_dir[PATH_MAX];
+};
+
+static struct p9_dev p9dev;
+
+/* Warning: Immediately use value returned from this function */
+static const char *rel_to_abs(const char *path, char *abs_path)
+{
+	sprintf(abs_path, "%s/%s", p9dev.root_dir, path);
+
+	return abs_path;
+}
+
+static bool virtio_p9_dev_in(void *data, unsigned long offset, int size, u32 count)
+{
+	u8 *config_space = (u8 *) p9dev.config;
+
+	if (size != 1 || count != 1)
+		return false;
+
+	ioport__write8(data, config_space[offset - VIRTIO_MSI_CONFIG_VECTOR]);
+
+	return true;
+}
+
+static bool virtio_p9_pci_io_in(struct kvm *kvm, u16 port, void *data, int size, u32 count)
+{
+	unsigned long offset;
+	bool ret = true;
+
+	offset = port - IOPORT_VIRTIO_P9;
+
+	switch (offset) {
+	case VIRTIO_PCI_HOST_FEATURES:
+		ioport__write32(data, p9dev.features);
+		ret = true;
+		break;
+	case VIRTIO_PCI_GUEST_FEATURES:
+	case VIRTIO_PCI_QUEUE_SEL:
+	case VIRTIO_PCI_QUEUE_NOTIFY:
+		ret = false;
+		break;
+	case VIRTIO_PCI_QUEUE_PFN:
+		ioport__write32(data, p9dev.vqs[p9dev.queue_selector].pfn);
+		break;
+	case VIRTIO_PCI_QUEUE_NUM:
+		ioport__write16(data, VIRTIO_P9_QUEUE_SIZE);
+		break;
+	case VIRTIO_PCI_STATUS:
+		ioport__write8(data, p9dev.status);
+		break;
+	case VIRTIO_PCI_ISR:
+		ioport__write8(data, p9dev.isr);
+		kvm__irq_line(kvm, virtio_p9_pci_device.irq_line, VIRTIO_IRQ_LOW);
+		p9dev.isr = VIRTIO_IRQ_LOW;
+		break;
+	default:
+		ret = virtio_p9_dev_in(data, offset, size, count);
+		break;
+	};
+
+	return ret;
+}
+
+static int omode2uflags(u8 mode)
+{
+	int ret = 0;
+
+	/* Basic open modes are same as uflags */
+	ret = mode & 3;
+
+	/* Everything else is different */
+	if (mode & P9_OTRUNC)
+		ret |= O_TRUNC;
+
+	if (mode & P9_OAPPEND)
+		ret |= O_APPEND;
+
+	if (mode & P9_OEXCL)
+		ret |= O_EXCL;
+
+	return ret;
+}
+
+static void st2qid(struct stat *st, struct p9_qid *qid)
+{
+	*qid = (struct p9_qid) {
+		.path		= st->st_ino,
+		.version	= st->st_mtime,
+	};
+
+	if (S_ISDIR(st->st_mode))
+		qid->type	|= P9_QTDIR;
+}
+
+static void close_fid(u32 fid)
+{
+	if (p9dev.fids[fid].fd > 0) {
+		close(p9dev.fids[fid].fd);
+		p9dev.fids[fid].fd = -1;
+	}
+	if (p9dev.fids[fid].dir) {
+		closedir(p9dev.fids[fid].dir);
+		p9dev.fids[fid].dir = NULL;
+	}
+}
+
+static void set_p9msg_hdr(struct p9_msg *msg, u32 size, u8 cmd, u16 tag)
+{
+	*msg = (struct p9_msg) {
+		.size	= size,
+		.tag	= tag,
+		.cmd	= cmd,
+	};
+}
+
+static bool virtio_p9_version(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg = iov[0].iov_base;
+	struct p9_rversion *rversion = (struct p9_rversion *)outmsg->msg;
+
+	rversion->msize		= 4096;
+	rversion->version.len	= strlen(VIRTIO_P9_VERSION);
+	memcpy(&rversion->version.str, VIRTIO_P9_VERSION, rversion->version.len);
+
+	*outlen = VIRTIO_P9_HDR_LEN + rversion->version.len + sizeof(u16) + sizeof(u32);
+	set_p9msg_hdr(outmsg, *outlen, P9_RVERSION, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_clunk(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg = iov[0].iov_base;
+	struct p9_tclunk *tclunk = (struct p9_tclunk *)msg->msg;
+
+	close_fid(tclunk->fid);
+
+	*outlen = VIRTIO_P9_HDR_LEN;
+	set_p9msg_hdr(outmsg, *outlen, P9_RCLUNK, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_open(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg	= iov[0].iov_base;
+	struct p9_topen *topen	= (struct p9_topen *)msg->msg;
+	struct p9_ropen *ropen	= (struct p9_ropen *)outmsg->msg;
+	struct p9_fid *new_fid	= &p9dev.fids[topen->fid];
+	struct stat st;
+
+	if (stat(new_fid->abs_path, &st) < 0)
+		return false;
+
+	st2qid(&st, &ropen->qid);
+	ropen->iounit = 0;
+
+	if (new_fid->is_dir)
+		new_fid->dir	= opendir(new_fid->abs_path);
+	else
+		new_fid->fd	= open(new_fid->abs_path, omode2uflags(topen->mode));
+
+	*outlen = VIRTIO_P9_HDR_LEN + sizeof(*ropen);
+	set_p9msg_hdr(outmsg, *outlen, P9_ROPEN, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_create(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg		= iov[0].iov_base;
+	struct p9_tcreate *tcreate	= (struct p9_tcreate *)msg->msg;
+	struct p9_rcreate *rcreate	= (struct p9_rcreate *)outmsg->msg;
+	struct p9_fid *fid		= &p9dev.fids[tcreate->fid];
+	struct stat st;
+	u8 mode;
+	u32 perm;
+
+	rcreate->iounit = 0;
+
+	/* Get last byte of the variable length struct */
+	mode = *((u8 *)msg + msg->size - 1);
+	perm = *(u32 *)((u8 *)msg + msg->size - 5);
+
+	sprintf(fid->path, "%s/%.*s", fid->path, tcreate->name.len, (char *)&tcreate->name.str);
+
+	close_fid(tcreate->fid);
+
+	if (perm & P9_DMDIR) {
+		mkdir(fid->abs_path, perm & 0xFFFF);
+		fid->dir = opendir(fid->abs_path);
+		fid->is_dir = 1;
+	} else {
+		fid->fd = open(fid->abs_path, omode2uflags(mode) | O_CREAT, 0777);
+	}
+
+	if (stat(fid->abs_path, &st) < 0)
+		return false;
+
+	st2qid(&st, &rcreate->qid);
+
+	*outlen = VIRTIO_P9_HDR_LEN + sizeof(*rcreate);
+	set_p9msg_hdr(outmsg, *outlen, P9_RCREATE, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_walk(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg	= iov[0].iov_base;
+	struct p9_twalk *twalk	= (struct p9_twalk *)msg->msg;
+	struct p9_rwalk *rwalk	= (struct p9_rwalk *)outmsg->msg;
+	struct p9_str *str	= twalk->wnames;
+	struct p9_fid *new_fid	= &p9dev.fids[twalk->newfid];
+	u8 i;
+
+	rwalk->nwqid = 0;
+	if (twalk->nwname) {
+		struct p9_fid *fid = &p9dev.fids[twalk->fid];
+
+		for (i = 0; i < twalk->nwname; i++) {
+			char tmp[PATH_MAX] = {0};
+			char full_path[PATH_MAX];
+			struct stat st;
+
+			/* Format the new path we're 'walk'ing into */
+			sprintf(tmp, "%s/%.*s", fid->path, str->len, (char *)&str->str);
+
+			if (stat(rel_to_abs(tmp, full_path), &st) < 0)
+				break;
+
+			st2qid(&st, &rwalk->wqids[i]);
+			new_fid->is_dir = S_ISDIR(st.st_mode);
+			strcpy(new_fid->path, tmp);
+			new_fid->fid = twalk->newfid;
+			rwalk->nwqid++;
+		}
+	} else {
+		new_fid->is_dir = p9dev.fids[twalk->fid].is_dir;
+		strcpy(new_fid->path, p9dev.fids[twalk->fid].path);
+		new_fid->fid	= twalk->newfid;
+	}
+
+	*outlen = VIRTIO_P9_HDR_LEN + sizeof(u16) + sizeof(struct p9_qid) * rwalk->nwqid;
+	set_p9msg_hdr(outmsg, *outlen, P9_RWALK, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_attach(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg = iov[0].iov_base;
+	struct p9_rattach *rattach = (struct p9_rattach *)outmsg->msg;
+	struct p9_tattach *tattach = (struct p9_tattach *)msg->msg;
+	struct stat st;
+	struct p9_fid *fid;
+	u32 i;
+
+	/* Reset everything */
+	for (i = 0; i < VIRTIO_P9_MAX_FID; i++)
+		p9dev.fids[i].fid = P9_NOFID;
+
+	if (stat(p9dev.root_dir, &st) < 0)
+		return false;
+
+	st2qid(&st, &rattach->qid);
+
+	fid = &p9dev.fids[tattach->fid];
+	fid->fid = tattach->fid;
+	fid->is_dir = 1;
+	strcpy(fid->path, "/");
+
+	*outlen = VIRTIO_P9_HDR_LEN + sizeof(*rattach);
+	set_p9msg_hdr(outmsg, *outlen, P9_RATTACH, msg->tag);
+
+	return true;
+}
+
+static u32 virtio_p9_fill_stat(const char *name, struct stat *st, struct p9_rstat *rstat)
+{
+	struct p9_str *str;
+
+	rstat->stat.type = 0;
+	rstat->stat.dev = 0;
+	st2qid(st, &rstat->stat.qid);
+	rstat->stat.mode = st->st_mode;
+	rstat->stat.length = st->st_size;
+	if (S_ISDIR(st->st_mode)) {
+		rstat->stat.length = 0;
+		rstat->stat.mode |= P9_DMDIR;
+	}
+
+	rstat->stat.atime = st->st_atime;
+	rstat->stat.mtime = st->st_mtime;
+
+	str = (struct p9_str *)&rstat->stat.name;
+	str->len = strlen(name);
+	memcpy(&str->str, name, str->len);
+	str = (void *)str + str->len + sizeof(u16);
+
+	/* TODO: Pass usernames to the client */
+	str->len = 0;
+	str = (void *)str + sizeof(u16);
+	str->len = 0;
+	str = (void *)str + sizeof(u16);
+	str->len = 0;
+	str = (void *)str + sizeof(u16);
+
+	/* We subtract a u16 here because rstat->size doesn't include rstat->size itself */
+	rstat->stat.size = (void *)str - (void *)&rstat->stat - sizeof(u16);
+
+	return rstat->stat.size + sizeof(u16);
+}
+
+static bool virtio_p9_read(struct p9_msg *msg, u32 len, struct iovec *iov, int iovcnt, u32 *outlen)
+{
+	struct p9_msg *outmsg	= iov[0].iov_base;
+	struct p9_tread *tread	= (struct p9_tread *)msg->msg;
+	struct p9_rread *rread	= (struct p9_rread *)outmsg->msg;
+	struct p9_rstat *rstat	= (struct p9_rstat *)iov[1].iov_base;
+	struct p9_fid *fid	= &p9dev.fids[tread->fid];
+	struct stat st;
+
+	rread->count = 0;
+
+	if (fid->is_dir) {
+		/* If reading a dir, fill the buffer with p9_stat entries */
+		struct dirent *cur = readdir(fid->dir);
+		char full_path[PATH_MAX];
+
+		while (cur) {
+			u32 read;
+
+			stat(rel_to_abs(cur->d_name, full_path), &st);
+			read = virtio_p9_fill_stat(cur->d_name, &st, rstat);
+			rread->count += read;
+			rstat = (void *)rstat + read;
+			cur = readdir(fid->dir);
+		}
+	} else {
+		iov[0].iov_base += VIRTIO_P9_HDR_LEN + sizeof(u32);
+		iov[0].iov_len -= VIRTIO_P9_HDR_LEN + sizeof(u32);
+		rread->count = preadv(fid->fd, iov, iovcnt, tread->offset);
+		if (rread->count > tread->count)
+			rread->count = tread->count;
+	}
+
+	*outlen = VIRTIO_P9_HDR_LEN + sizeof(u32) + rread->count;
+	set_p9msg_hdr(outmsg, *outlen, P9_RREAD, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_stat(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg = iov[0].iov_base;
+	struct p9_tstat *tstat = (struct p9_tstat *)msg->msg;
+	struct p9_rstat *rstat = (struct p9_rstat *)(outmsg->msg + sizeof(u16));
+	struct stat st;
+	struct p9_fid *fid = &p9dev.fids[tstat->fid];
+	u32 ret;
+
+	if (stat(fid->abs_path, &st) < 0)
+		return false;
+
+	ret = virtio_p9_fill_stat(fid->path, &st, rstat);
+
+	*outlen = VIRTIO_P9_HDR_LEN + ret + sizeof(u16) * 2;
+	set_p9msg_hdr(outmsg, *outlen, P9_RSTAT, msg->tag);
+	return true;
+}
+
+static bool virtio_p9_wstat(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg = iov[0].iov_base;
+	struct p9_twstat *twstat = (struct p9_twstat *)msg->msg;
+	struct p9_str *str;
+	struct p9_fid *fid = &p9dev.fids[twstat->fid];
+	int res;
+
+	if (twstat->stat.length != -1UL)
+		res = ftruncate(fid->fd, twstat->stat.length);
+
+	if (twstat->stat.mode != -1U)
+		chmod(fid->abs_path, twstat->stat.mode & 0xFFFF);
+
+	str = (void *)&twstat->stat.name + sizeof(u16);
+	if (str->len > 0) {
+		char new_name[PATH_MAX] = {0};
+		char full_path[PATH_MAX];
+		char *last_dir = strrchr(fid->path, '/');
+
+		/* We need to get the full file name out of twstat->name */
+		if (last_dir)
+			strncpy(new_name, fid->path, last_dir - fid->path + 1);
+
+		memcpy(new_name + strlen(new_name), &str->str, str->len);
+
+		/* fid is reused for the new file */
+		rename(fid->abs_path, rel_to_abs(new_name, full_path));
+		sprintf(fid->path, "%s", new_name);
+	}
+
+	*outlen = VIRTIO_P9_HDR_LEN;
+	set_p9msg_hdr(outmsg, *outlen, P9_RWSTAT, msg->tag);
+	return true;
+}
+
+static bool virtio_p9_remove(struct p9_msg *msg, u32 len, struct iovec *iov, u32 *outlen)
+{
+	struct p9_msg *outmsg = iov[0].iov_base;
+	struct p9_tremove *tremove = (struct p9_tremove *)msg->msg;
+	struct p9_fid *fid = &p9dev.fids[tremove->fid];
+
+	close_fid(tremove->fid);
+	if (fid->is_dir)
+		rmdir(fid->abs_path);
+	else
+		unlink(fid->abs_path);
+
+	*outlen = VIRTIO_P9_HDR_LEN;
+	set_p9msg_hdr(outmsg, *outlen, P9_RREMOVE, msg->tag);
+	return true;
+}
+
+static bool virtio_p9_write(struct p9_msg *msg, u32 len, struct iovec *iov, int iovcnt, u32 *outlen)
+{
+	struct p9_msg *outmsg;
+	struct p9_rwrite *rwrite;
+	struct p9_twrite *twrite = (struct p9_twrite *)msg->msg;
+	struct p9_fid *fid = &p9dev.fids[twrite->fid];
+
+	if (iovcnt == 1) {
+		outmsg = iov[0].iov_base;
+		rwrite = (struct p9_rwrite *)outmsg->msg;
+		rwrite->count = pwrite(fid->fd, &twrite->data, twrite->count, twrite->offset);
+	} else {
+		outmsg = iov[2].iov_base;
+		rwrite = (struct p9_rwrite *)outmsg->msg;
+		rwrite->count = pwrite(fid->fd, iov[1].iov_base, twrite->count, twrite->offset);
+	}
+
+	*outlen = VIRTIO_P9_HDR_LEN + sizeof(u32);
+	set_p9msg_hdr(outmsg, *outlen, P9_RWRITE, msg->tag);
+
+	return true;
+}
+
+static bool virtio_p9_do_io_request(struct kvm *kvm, struct virt_queue *queue)
+{
+	struct iovec iov[VIRTIO_P9_QUEUE_SIZE];
+	u16 out, in, head;
+	struct p9_msg *msg;
+	u32 len = 0;
+
+	head		= virt_queue__get_iov(queue, iov, &out, &in, kvm);
+	msg		= iov[0].iov_base;
+
+	switch (msg->cmd) {
+	case P9_TVERSION:
+		virtio_p9_version(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TATTACH:
+		virtio_p9_attach(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TSTAT:
+		virtio_p9_stat(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TCLUNK:
+		virtio_p9_clunk(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TWALK:
+		virtio_p9_walk(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TOPEN:
+		virtio_p9_open(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TREAD:
+		virtio_p9_read(msg, iov[0].iov_len, iov+1, in, &len);
+		break;
+	case P9_TCREATE:
+		virtio_p9_create(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TWSTAT:
+		virtio_p9_wstat(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TREMOVE:
+		virtio_p9_remove(msg, iov[0].iov_len, iov+1, &len);
+		break;
+	case P9_TWRITE:
+		virtio_p9_write(msg, iov[0].iov_len, iov+1, out, &len);
+		break;
+	default:
+		printf("Unsupported P9 message type: %u\n", msg->cmd);
+		break;
+	}
+	virt_queue__set_used_elem(queue, head, len);
+
+	return true;
+}
+
+static void virtio_p9_do_io(struct kvm *kvm, void *param)
+{
+	struct virt_queue *vq = param;
+
+	while (virt_queue__available(vq)) {
+		virtio_p9_do_io_request(kvm, vq);
+		virt_queue__trigger_irq(vq, virtio_p9_pci_device.irq_line, &p9dev.isr, kvm);
+	}
+}
+
+static bool virtio_p9_pci_io_out(struct kvm *kvm, u16 port, void *data, int size, u32 count)
+{
+	unsigned long offset;
+	bool ret = true;
+
+	offset		= port - IOPORT_VIRTIO_P9;
+
+	switch (offset) {
+	case VIRTIO_MSI_QUEUE_VECTOR:
+	case VIRTIO_PCI_GUEST_FEATURES:
+		break;
+	case VIRTIO_PCI_QUEUE_PFN: {
+		struct virt_queue *queue;
+		void *p;
+
+		queue			= &p9dev.vqs[p9dev.queue_selector];
+		queue->pfn		= ioport__read32(data);
+		p			= guest_pfn_to_host(kvm, queue->pfn);
+
+		vring_init(&queue->vring, VIRTIO_P9_QUEUE_SIZE, p, VIRTIO_PCI_VRING_ALIGN);
+
+		p9dev.jobs[p9dev.queue_selector] = thread_pool__add_job(kvm, virtio_p9_do_io, queue);
+
+		break;
+	}
+	case VIRTIO_PCI_QUEUE_SEL:
+		p9dev.queue_selector	= ioport__read16(data);
+		break;
+	case VIRTIO_PCI_QUEUE_NOTIFY: {
+		u16 queue_index;
+		queue_index		= ioport__read16(data);
+		thread_pool__do_job(p9dev.jobs[queue_index]);
+		break;
+	}
+	case VIRTIO_PCI_STATUS:
+		p9dev.status		= ioport__read8(data);
+		break;
+	case VIRTIO_MSI_CONFIG_VECTOR:
+		p9dev.config_vector	= VIRTIO_MSI_NO_VECTOR;
+		break;
+	default:
+		ret			= false;
+		break;
+	};
+
+	return ret;
+}
+
+static struct ioport_operations virtio_p9_io_ops = {
+	.io_in				= virtio_p9_pci_io_in,
+	.io_out				= virtio_p9_pci_io_out,
+};
+
+void virtio_9p__init(struct kvm *kvm, const char *root)
+{
+	u8 pin, line, dev;
+	u32 i, root_len;
+
+	p9dev.config = calloc(1, sizeof(*p9dev.config) + sizeof(VIRTIO_P9_TAG));
+	if (p9dev.config == NULL)
+		return;
+
+	strcpy(p9dev.root_dir, root);
+	root_len = strlen(root);
+
+	/*
+	 * We prefix the full path in all fids, This allows us to get the
+	 * absolute path of an fid without playing with strings.
+	 */
+	for (i = 0; i < VIRTIO_P9_MAX_FID; i++) {
+		strcpy(p9dev.fids[i].abs_path, root);
+		p9dev.fids[i].path = p9dev.fids[i].abs_path + root_len;
+	}
+
+	p9dev.config->tag_len = strlen(VIRTIO_P9_TAG);
+	memcpy(p9dev.config->tag, VIRTIO_P9_TAG, strlen(VIRTIO_P9_TAG));
+	p9dev.features |= 1 << VIRTIO_9P_MOUNT_TAG;
+
+	if (irq__register_device(VIRTIO_ID_9P, &dev, &pin, &line) < 0)
+		return;
+
+	virtio_p9_pci_device.irq_pin	= pin;
+	virtio_p9_pci_device.irq_line	= line;
+	pci__register(&virtio_p9_pci_device, dev);
+
+	ioport__register(IOPORT_VIRTIO_P9, &virtio_p9_io_ops, IOPORT_VIRTIO_P9_SIZE);
+}
