virtio-9p: Add a virtio 9p device to qemu

This patch doesn't implement the 9p protocol handling
code. It adds a simple device which dump the protocol data.

[jvrao@linux.vnet.ibm.com: Little-Endian to host format conversion]
[aneesh.kumar@linux.vnet.ibm.com: Multiple-mounts support]

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

7 files changed, 1039 insertions, 0 deletions

diff --git a/hw/9p.h b/hw/9p.h
new file mode 100644
index 0000000..5fdd770
--- /dev/null
+++ b/hw/9p.h
@@ -0,0 +1,26 @@
+/*
+ * Virtio 9p
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_9P_H
+#define QEMU_9P_H
+
+#include <stdbool.h>
+
+typedef struct V9fsConf
+{
+    /* tag name for the device */
+    char *tag;
+    char *fsdev_id;
+} V9fsConf;
+
+#endif
diff --git a/hw/virtio-9p-debug.c b/hw/virtio-9p-debug.c
new file mode 100644
index 0000000..2fb2673
--- /dev/null
+++ b/hw/virtio-9p-debug.c
@@ -0,0 +1,484 @@
+/*
+ * Virtio 9p PDU debug
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+#include "virtio.h"
+#include "pc.h"
+#include "virtio-9p.h"
+#include "virtio-9p-debug.h"
+
+#define BUG_ON(cond) assert(!(cond))
+
+static FILE *llogfile;
+
+static struct iovec *get_sg(V9fsPDU *pdu, int rx)
+{
+    if (rx) {
+        return pdu->elem.in_sg;
+    }
+    return pdu->elem.out_sg;
+}
+
+static int get_sg_count(V9fsPDU *pdu, int rx)
+{
+    if (rx) {
+        return pdu->elem.in_num;
+    }
+    return pdu->elem.out_num;
+
+}
+
+static void pprint_int8(V9fsPDU *pdu, int rx, size_t *offsetp,
+                        const char *name)
+{
+    size_t copied;
+    int count = get_sg_count(pdu, rx);
+    size_t offset = *offsetp;
+    struct iovec *sg = get_sg(pdu, rx);
+    int8_t value;
+
+    copied = do_pdu_unpack(&value, sg, count, offset, sizeof(value));
+
+    BUG_ON(copied != sizeof(value));
+    offset += sizeof(value);
+    fprintf(llogfile, "%s=0x%x", name, value);
+    *offsetp = offset;
+}
+
+static void pprint_int16(V9fsPDU *pdu, int rx, size_t *offsetp,
+                        const char *name)
+{
+    size_t copied;
+    int count = get_sg_count(pdu, rx);
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    int16_t value;
+
+
+    copied = do_pdu_unpack(&value, sg, count, offset, sizeof(value));
+
+    BUG_ON(copied != sizeof(value));
+    offset += sizeof(value);
+    fprintf(llogfile, "%s=0x%x", name, value);
+    *offsetp = offset;
+}
+
+static void pprint_int32(V9fsPDU *pdu, int rx, size_t *offsetp,
+                        const char *name)
+{
+    size_t copied;
+    int count = get_sg_count(pdu, rx);
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    int32_t value;
+
+
+    copied = do_pdu_unpack(&value, sg, count, offset, sizeof(value));
+
+    BUG_ON(copied != sizeof(value));
+    offset += sizeof(value);
+    fprintf(llogfile, "%s=0x%x", name, value);
+    *offsetp = offset;
+}
+
+static void pprint_int64(V9fsPDU *pdu, int rx, size_t *offsetp,
+                        const char *name)
+{
+    size_t copied;
+    int count = get_sg_count(pdu, rx);
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    int64_t value;
+
+
+    copied = do_pdu_unpack(&value, sg, count, offset, sizeof(value));
+
+    BUG_ON(copied != sizeof(value));
+    offset += sizeof(value);
+    fprintf(llogfile, "%s=0x%" PRIx64, name, value);
+    *offsetp = offset;
+}
+
+static void pprint_str(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    int sg_count = get_sg_count(pdu, rx);
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    uint16_t tmp_size, size;
+    size_t result;
+    size_t copied = 0;
+    int i = 0;
+
+    /* get the size */
+    copied = do_pdu_unpack(&tmp_size, sg, sg_count, offset, sizeof(tmp_size));
+    BUG_ON(copied != sizeof(tmp_size));
+    size = le16_to_cpupu(&tmp_size);
+    offset += copied;
+
+    fprintf(llogfile, "%s=", name);
+    for (i = 0; size && i < sg_count; i++) {
+        size_t len;
+        if (offset >= sg[i].iov_len) {
+            /* skip this sg */
+            offset -= sg[i].iov_len;
+            continue;
+        } else {
+            len = MIN(sg[i].iov_len - offset, size);
+            result = fwrite(sg[i].iov_base + offset, 1, len, llogfile);
+            BUG_ON(result != len);
+            size -= len;
+            copied += len;
+            if (size) {
+                offset = 0;
+                continue;
+            }
+        }
+    }
+    *offsetp += copied;
+}
+
+static void pprint_qid(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    fprintf(llogfile, "%s={", name);
+    pprint_int8(pdu, rx, offsetp, "type");
+    pprint_int32(pdu, rx, offsetp, ", version");
+    pprint_int64(pdu, rx, offsetp, ", path");
+    fprintf(llogfile, "}");
+}
+
+static void pprint_stat(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    fprintf(llogfile, "%s={", name);
+    pprint_int16(pdu, rx, offsetp, "size");
+    pprint_int16(pdu, rx, offsetp, ", type");
+    pprint_int32(pdu, rx, offsetp, ", dev");
+    pprint_qid(pdu, rx, offsetp, ", qid");
+    pprint_int32(pdu, rx, offsetp, ", mode");
+    pprint_int32(pdu, rx, offsetp, ", atime");
+    pprint_int32(pdu, rx, offsetp, ", mtime");
+    pprint_int64(pdu, rx, offsetp, ", length");
+    pprint_str(pdu, rx, offsetp, ", name");
+    pprint_str(pdu, rx, offsetp, ", uid");
+    pprint_str(pdu, rx, offsetp, ", gid");
+    pprint_str(pdu, rx, offsetp, ", muid");
+    if (dotu) {
+        pprint_str(pdu, rx, offsetp, ", extension");
+        pprint_int32(pdu, rx, offsetp, ", uid");
+        pprint_int32(pdu, rx, offsetp, ", gid");
+        pprint_int32(pdu, rx, offsetp, ", muid");
+    }
+    fprintf(llogfile, "}");
+}
+
+static void pprint_strs(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    int sg_count = get_sg_count(pdu, rx);
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    uint16_t tmp_count, count, i;
+    size_t copied = 0;
+
+    fprintf(llogfile, "%s={", name);
+
+    /* Get the count */
+    copied = do_pdu_unpack(&tmp_count, sg, sg_count, offset, sizeof(tmp_count));
+    BUG_ON(copied != sizeof(tmp_count));
+    count = le16_to_cpupu(&tmp_count);
+    offset += copied;
+
+    for (i = 0; i < count; i++) {
+        char str[512];
+        if (i) {
+            fprintf(llogfile, ", ");
+        }
+        snprintf(str, sizeof(str), "[%d]", i);
+        pprint_str(pdu, rx, &offset, str);
+    }
+
+    fprintf(llogfile, "}");
+
+    *offsetp = offset;
+}
+
+static void pprint_qids(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    int sg_count = get_sg_count(pdu, rx);
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    uint16_t tmp_count, count, i;
+    size_t copied = 0;
+
+    fprintf(llogfile, "%s={", name);
+
+    copied = do_pdu_unpack(&tmp_count, sg, sg_count, offset, sizeof(tmp_count));
+    BUG_ON(copied != sizeof(tmp_count));
+    count = le16_to_cpupu(&tmp_count);
+    offset += copied;
+
+    for (i = 0; i < count; i++) {
+        char str[512];
+        if (i) {
+            fprintf(llogfile, ", ");
+        }
+        snprintf(str, sizeof(str), "[%d]", i);
+        pprint_qid(pdu, rx, &offset, str);
+    }
+
+    fprintf(llogfile, "}");
+
+    *offsetp = offset;
+}
+
+static void pprint_sg(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    struct iovec *sg = get_sg(pdu, rx);
+    unsigned int count;
+    int i;
+
+    if (rx) {
+        count = pdu->elem.in_num;
+    } else {
+        count = pdu->elem.out_num;
+    }
+
+    fprintf(llogfile, "%s={", name);
+    for (i = 0; i < count; i++) {
+        if (i) {
+            fprintf(llogfile, ", ");
+        }
+        fprintf(llogfile, "(%p, 0x%zx)", sg[i].iov_base, sg[i].iov_len);
+    }
+    fprintf(llogfile, "}");
+}
+
+/* FIXME: read from a directory fid returns serialized stat_t's */
+#ifdef DEBUG_DATA
+static void pprint_data(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
+{
+    struct iovec *sg = get_sg(pdu, rx);
+    size_t offset = *offsetp;
+    unsigned int count;
+    int32_t size;
+    int total, i, j;
+    ssize_t len;
+
+    if (rx) {
+        count = pdu->elem.in_num;
+    } else
+        count = pdu->elem.out_num;
+    }
+
+    BUG_ON((offset + sizeof(size)) > sg[0].iov_len);
+
+    memcpy(&size, sg[0].iov_base + offset, sizeof(size));
+    offset += sizeof(size);
+
+    fprintf(llogfile, "size: %x\n", size);
+
+    sg[0].iov_base += 11; /* skip header */
+    sg[0].iov_len -= 11;
+
+    total = 0;
+    for (i = 0; i < count; i++) {
+        total += sg[i].iov_len;
+        if (total >= size) {
+            /* trim sg list so writev does the right thing */
+            sg[i].iov_len -= (total - size);
+            i++;
+            break;
+        }
+    }
+
+    fprintf(llogfile, "%s={\"", name);
+    fflush(llogfile);
+    for (j = 0; j < i; j++) {
+        if (j) {
+            fprintf(llogfile, "\", \"");
+            fflush(llogfile);
+        }
+
+        do {
+            len = writev(fileno(llogfile), &sg[j], 1);
+        } while (len == -1 && errno == EINTR);
+        fprintf(llogfile, "len == %ld: %m\n", len);
+        BUG_ON(len != sg[j].iov_len);
+    }
+    fprintf(llogfile, "\"}");
+
+    sg[0].iov_base -= 11;
+    sg[0].iov_len += 11;
+
+}
+#endif
+
+void pprint_pdu(V9fsPDU *pdu)
+{
+    size_t offset = 7;
+
+    if (llogfile == NULL) {
+        llogfile = fopen("/tmp/pdu.log", "w");
+    }
+
+    switch (pdu->id) {
+    case P9_TVERSION:
+        fprintf(llogfile, "TVERSION: (");
+        pprint_int32(pdu, 0, &offset, "msize");
+        pprint_str(pdu, 0, &offset, ", version");
+        break;
+    case P9_RVERSION:
+        fprintf(llogfile, "RVERSION: (");
+        pprint_int32(pdu, 1, &offset, "msize");
+        pprint_str(pdu, 1, &offset, ", version");
+        break;
+    case P9_TAUTH:
+        fprintf(llogfile, "TAUTH: (");
+        pprint_int32(pdu, 0, &offset, "afid");
+        pprint_str(pdu, 0, &offset, ", uname");
+        pprint_str(pdu, 0, &offset, ", aname");
+        if (dotu) {
+            pprint_int32(pdu, 0, &offset, ", n_uname");
+        }
+        break;
+    case P9_RAUTH:
+        fprintf(llogfile, "RAUTH: (");
+        pprint_qid(pdu, 1, &offset, "qid");
+        break;
+    case P9_TATTACH:
+        fprintf(llogfile, "TATTACH: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int32(pdu, 0, &offset, ", afid");
+        pprint_str(pdu, 0, &offset, ", uname");
+        pprint_str(pdu, 0, &offset, ", aname");
+        if (dotu) {
+            pprint_int32(pdu, 0, &offset, ", n_uname");
+        }
+        break;
+    case P9_RATTACH:
+        fprintf(llogfile, "RATTACH: (");
+        pprint_qid(pdu, 1, &offset, "qid");
+        break;
+    case P9_TERROR:
+        fprintf(llogfile, "TERROR: (");
+        break;
+    case P9_RERROR:
+        fprintf(llogfile, "RERROR: (");
+        pprint_str(pdu, 1, &offset, "ename");
+        if (dotu) {
+            pprint_int32(pdu, 1, &offset, ", ecode");
+        }
+        break;
+    case P9_TFLUSH:
+        fprintf(llogfile, "TFLUSH: (");
+        pprint_int16(pdu, 0, &offset, "oldtag");
+        break;
+    case P9_RFLUSH:
+        fprintf(llogfile, "RFLUSH: (");
+        break;
+    case P9_TWALK:
+        fprintf(llogfile, "TWALK: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int32(pdu, 0, &offset, ", newfid");
+        pprint_strs(pdu, 0, &offset, ", wnames");
+        break;
+    case P9_RWALK:
+        fprintf(llogfile, "RWALK: (");
+        pprint_qids(pdu, 1, &offset, "wqids");
+        break;
+    case P9_TOPEN:
+        fprintf(llogfile, "TOPEN: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int8(pdu, 0, &offset, ", mode");
+        break;
+    case P9_ROPEN:
+        fprintf(llogfile, "ROPEN: (");
+        pprint_qid(pdu, 1, &offset, "qid");
+        pprint_int32(pdu, 1, &offset, ", iounit");
+        break;
+    case P9_TCREATE:
+        fprintf(llogfile, "TCREATE: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_str(pdu, 0, &offset, ", name");
+        pprint_int32(pdu, 0, &offset, ", perm");
+        pprint_int8(pdu, 0, &offset, ", mode");
+        if (dotu) {
+            pprint_str(pdu, 0, &offset, ", extension");
+        }
+        break;
+    case P9_RCREATE:
+        fprintf(llogfile, "RCREATE: (");
+        pprint_qid(pdu, 1, &offset, "qid");
+        pprint_int32(pdu, 1, &offset, ", iounit");
+        break;
+    case P9_TREAD:
+        fprintf(llogfile, "TREAD: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int64(pdu, 0, &offset, ", offset");
+        pprint_int32(pdu, 0, &offset, ", count");
+        pprint_sg(pdu, 0, &offset, ", sg");
+        break;
+    case P9_RREAD:
+        fprintf(llogfile, "RREAD: (");
+        pprint_int32(pdu, 1, &offset, "count");
+        pprint_sg(pdu, 1, &offset, ", sg");
+        offset = 7;
+#ifdef DEBUG_DATA
+        pprint_data(pdu, 1, &offset, ", data");
+#endif
+        break;
+    case P9_TWRITE:
+        fprintf(llogfile, "TWRITE: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int64(pdu, 0, &offset, ", offset");
+        pprint_int32(pdu, 0, &offset, ", count");
+        break;
+    case P9_RWRITE:
+        fprintf(llogfile, "RWRITE: (");
+        pprint_int32(pdu, 1, &offset, "count");
+        break;
+    case P9_TCLUNK:
+        fprintf(llogfile, "TCLUNK: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        break;
+    case P9_RCLUNK:
+        fprintf(llogfile, "RCLUNK: (");
+        break;
+    case P9_TREMOVE:
+        fprintf(llogfile, "TREMOVE: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        break;
+    case P9_RREMOVE:
+        fprintf(llogfile, "RREMOVE: (");
+        break;
+    case P9_TSTAT:
+        fprintf(llogfile, "TSTAT: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        break;
+    case P9_RSTAT:
+        fprintf(llogfile, "RSTAT: (");
+        offset += 2; /* ignored */
+        pprint_stat(pdu, 1, &offset, "stat");
+        break;
+    case P9_TWSTAT:
+        fprintf(llogfile, "TWSTAT: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        offset += 2; /* ignored */
+        pprint_stat(pdu, 0, &offset, ", stat");
+        break;
+    case P9_RWSTAT:
+        fprintf(llogfile, "RWSTAT: (");
+        break;
+    default:
+        fprintf(llogfile, "unknown(%d): (", pdu->id);
+        break;
+    }
+
+    fprintf(llogfile, ")\n");
+}
diff --git a/hw/virtio-9p-local.c b/hw/virtio-9p-local.c
new file mode 100644
index 0000000..379af60
--- /dev/null
+++ b/hw/virtio-9p-local.c
@@ -0,0 +1,17 @@
+/*
+ * Virtio 9p Posix callback
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+#include "virtio.h"
+#include "virtio-9p.h"
+
+FileOperations local_ops = {
+};
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
new file mode 100644
index 0000000..abd01c1
--- /dev/null
+++ b/hw/virtio-9p.c
@@ -0,0 +1,307 @@
+/*
+ * Virtio 9p backend
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "virtio.h"
+#include "pc.h"
+#include "qemu_socket.h"
+#include "virtio-9p.h"
+#include "fsdev/qemu-fsdev.h"
+#include "virtio-9p-debug.h"
+
+int dotu = 1;
+int debug_9p_pdu;
+
+static V9fsPDU *alloc_pdu(V9fsState *s)
+{
+    V9fsPDU *pdu = NULL;
+
+    if (!QLIST_EMPTY(&s->free_list)) {
+	pdu = QLIST_FIRST(&s->free_list);
+	QLIST_REMOVE(pdu, next);
+    }
+    return pdu;
+}
+
+static void free_pdu(V9fsState *s, V9fsPDU *pdu)
+{
+    if (pdu) {
+	QLIST_INSERT_HEAD(&s->free_list, pdu, next);
+    }
+}
+
+size_t pdu_packunpack(void *addr, struct iovec *sg, int sg_count,
+                        size_t offset, size_t size, int pack)
+{
+    int i = 0;
+    size_t copied = 0;
+
+    for (i = 0; size && i < sg_count; i++) {
+        size_t len;
+        if (offset >= sg[i].iov_len) {
+            /* skip this sg */
+            offset -= sg[i].iov_len;
+            continue;
+        } else {
+            len = MIN(sg[i].iov_len - offset, size);
+            if (pack) {
+                memcpy(sg[i].iov_base + offset, addr, len);
+            } else {
+                memcpy(addr, sg[i].iov_base + offset, len);
+            }
+            size -= len;
+            copied += len;
+            addr += len;
+            if (size) {
+                offset = 0;
+                continue;
+            }
+        }
+    }
+
+    return copied;
+}
+
+static void v9fs_version(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_attach(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_stat(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_walk(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_clunk(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_open(V9fsState *s, V9fsPDU *pdu)
+{    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+     }
+}
+
+static void v9fs_read(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_write(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_create(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_flush(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_remove(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+static void v9fs_wstat(V9fsState *s, V9fsPDU *pdu)
+{
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+}
+
+typedef void (pdu_handler_t)(V9fsState *s, V9fsPDU *pdu);
+
+static pdu_handler_t *pdu_handlers[] = {
+    [P9_TVERSION] = v9fs_version,
+    [P9_TATTACH] = v9fs_attach,
+    [P9_TSTAT] = v9fs_stat,
+    [P9_TWALK] = v9fs_walk,
+    [P9_TCLUNK] = v9fs_clunk,
+    [P9_TOPEN] = v9fs_open,
+    [P9_TREAD] = v9fs_read,
+#if 0
+    [P9_TAUTH] = v9fs_auth,
+#endif
+    [P9_TFLUSH] = v9fs_flush,
+    [P9_TCREATE] = v9fs_create,
+    [P9_TWRITE] = v9fs_write,
+    [P9_TWSTAT] = v9fs_wstat,
+    [P9_TREMOVE] = v9fs_remove,
+};
+
+static void submit_pdu(V9fsState *s, V9fsPDU *pdu)
+{
+    pdu_handler_t *handler;
+
+    if (debug_9p_pdu) {
+        pprint_pdu(pdu);
+    }
+
+    BUG_ON(pdu->id >= ARRAY_SIZE(pdu_handlers));
+
+    handler = pdu_handlers[pdu->id];
+    BUG_ON(handler == NULL);
+
+    handler(s, pdu);
+}
+
+static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    V9fsState *s = (V9fsState *)vdev;
+    V9fsPDU *pdu;
+    ssize_t len;
+
+    while ((pdu = alloc_pdu(s)) &&
+            (len = virtqueue_pop(vq, &pdu->elem)) != 0) {
+        uint8_t *ptr;
+
+        BUG_ON(pdu->elem.out_num == 0 || pdu->elem.in_num == 0);
+        BUG_ON(pdu->elem.out_sg[0].iov_len < 7);
+
+        ptr = pdu->elem.out_sg[0].iov_base;
+
+        memcpy(&pdu->size, ptr, 4);
+        pdu->id = ptr[4];
+        memcpy(&pdu->tag, ptr + 5, 2);
+
+        submit_pdu(s, pdu);
+    }
+
+    free_pdu(s, pdu);
+}
+
+static uint32_t virtio_9p_get_features(VirtIODevice *vdev, uint32_t features)
+{
+    features |= 1 << VIRTIO_9P_MOUNT_TAG;
+    return features;
+}
+
+static V9fsState *to_virtio_9p(VirtIODevice *vdev)
+{
+    return (V9fsState *)vdev;
+}
+
+static void virtio_9p_get_config(VirtIODevice *vdev, uint8_t *config)
+{
+    struct virtio_9p_config *cfg;
+    V9fsState *s = to_virtio_9p(vdev);
+
+    cfg = qemu_mallocz(sizeof(struct virtio_9p_config) +
+                        s->tag_len);
+    stw_raw(&cfg->tag_len, s->tag_len);
+    memcpy(cfg->tag, s->tag, s->tag_len);
+    memcpy(config, cfg, s->config_size);
+    qemu_free(cfg);
+}
+
+VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
+ {
+    V9fsState *s;
+    int i, len;
+    struct stat stat;
+    FsTypeEntry *fse;
+
+
+    s = (V9fsState *)virtio_common_init("virtio-9p",
+                                    VIRTIO_ID_9P,
+                                    sizeof(struct virtio_9p_config)+
+                                    MAX_TAG_LEN,
+                                    sizeof(V9fsState));
+
+    /* initialize pdu allocator */
+    QLIST_INIT(&s->free_list);
+    for (i = 0; i < (MAX_REQ - 1); i++) {
+	QLIST_INSERT_HEAD(&s->free_list, &s->pdus[i], next);
+    }
+
+    s->vq = virtio_add_queue(&s->vdev, MAX_REQ, handle_9p_output);
+
+    fse = get_fsdev_fsentry(conf->fsdev_id);
+
+    if (!fse) {
+        /* We don't have a fsdev identified by fsdev_id */
+        fprintf(stderr, "Virtio-9p device couldn't find fsdev "
+                    "with the id %s\n", conf->fsdev_id);
+        exit(1);
+    }
+
+    if (!fse->path || !conf->tag) {
+        /* we haven't specified a mount_tag or the path */
+        fprintf(stderr, "fsdev with id %s needs path "
+                "and Virtio-9p device needs mount_tag arguments\n",
+                conf->fsdev_id);
+        exit(1);
+    }
+
+    if (lstat(fse->path, &stat)) {
+        fprintf(stderr, "share path %s does not exist\n", fse->path);
+        exit(1);
+    } else if (!S_ISDIR(stat.st_mode)) {
+        fprintf(stderr, "share path %s is not a directory \n", fse->path);
+        exit(1);
+    }
+
+    s->ctx.fs_root = qemu_strdup(fse->path);
+    len = strlen(conf->tag);
+    if (len > MAX_TAG_LEN) {
+        len = MAX_TAG_LEN;
+    }
+    /* s->tag is non-NULL terminated string */
+    s->tag = qemu_malloc(len);
+    memcpy(s->tag, conf->tag, len);
+    s->tag_len = len;
+    s->ctx.uid = -1;
+
+    s->ops = fse->ops;
+    s->vdev.get_features = virtio_9p_get_features;
+    s->config_size = sizeof(struct virtio_9p_config) +
+                        s->tag_len;
+    s->vdev.get_config = virtio_9p_get_config;
+
+    return &s->vdev;
+}
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
new file mode 100644
index 0000000..b95dbe4
--- /dev/null
+++ b/hw/virtio-9p.h
@@ -0,0 +1,166 @@
+#ifndef _QEMU_VIRTIO_9P_H
+#define _QEMU_VIRTIO_9P_H
+
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/time.h>
+#include <utime.h>
+
+#include "file-op-9p.h"
+
+/* The feature bitmap for virtio 9P */
+/* The mount point is specified in a config variable */
+#define VIRTIO_9P_MOUNT_TAG 0
+
+enum {
+    P9_TVERSION = 100,
+    P9_RVERSION,
+    P9_TAUTH = 102,
+    P9_RAUTH,
+    P9_TATTACH = 104,
+    P9_RATTACH,
+    P9_TERROR = 106,
+    P9_RERROR,
+    P9_TFLUSH = 108,
+    P9_RFLUSH,
+    P9_TWALK = 110,
+    P9_RWALK,
+    P9_TOPEN = 112,
+    P9_ROPEN,
+    P9_TCREATE = 114,
+    P9_RCREATE,
+    P9_TREAD = 116,
+    P9_RREAD,
+    P9_TWRITE = 118,
+    P9_RWRITE,
+    P9_TCLUNK = 120,
+    P9_RCLUNK,
+    P9_TREMOVE = 122,
+    P9_RREMOVE,
+    P9_TSTAT = 124,
+    P9_RSTAT,
+    P9_TWSTAT = 126,
+    P9_RWSTAT,
+};
+
+
+/* qid.types */
+enum {
+    P9_QTDIR = 0x80,
+    P9_QTAPPEND = 0x40,
+    P9_QTEXCL = 0x20,
+    P9_QTMOUNT = 0x10,
+    P9_QTAUTH = 0x08,
+    P9_QTTMP = 0x04,
+    P9_QTSYMLINK = 0x02,
+    P9_QTLINK = 0x01,
+    P9_QTFILE = 0x00,
+};
+
+#define P9_NOTAG    (u16)(~0)
+#define P9_NOFID    (u32)(~0)
+#define P9_MAXWELEM 16
+
+typedef struct V9fsPDU V9fsPDU;
+
+struct V9fsPDU
+{
+    uint32_t size;
+    uint16_t tag;
+    uint8_t id;
+    VirtQueueElement elem;
+    QLIST_ENTRY(V9fsPDU) next;
+};
+
+
+/* FIXME
+ * 1) change user needs to set groups and stuff
+ */
+
+/* from Linux's linux/virtio_9p.h */
+
+/* The ID for virtio console */
+#define VIRTIO_ID_9P    9
+#define MAX_REQ         128
+#define MAX_TAG_LEN     32
+
+#define BUG_ON(cond) assert(!(cond))
+
+typedef struct V9fsFidState V9fsFidState;
+
+typedef struct V9fsString
+{
+    int16_t size;
+    char *data;
+} V9fsString;
+
+typedef struct V9fsQID
+{
+    int8_t type;
+    int32_t version;
+    int64_t path;
+} V9fsQID;
+
+typedef struct V9fsStat
+{
+    int16_t size;
+    int16_t type;
+    int32_t dev;
+    V9fsQID qid;
+    int32_t mode;
+    int32_t atime;
+    int32_t mtime;
+    int64_t length;
+    V9fsString name;
+    V9fsString uid;
+    V9fsString gid;
+    V9fsString muid;
+    /* 9p2000.u */
+    V9fsString extension;
+   int32_t n_uid;
+    int32_t n_gid;
+    int32_t n_muid;
+} V9fsStat;
+
+struct V9fsFidState
+{
+    int32_t fid;
+    V9fsString path;
+    int fd;
+    DIR *dir;
+    uid_t uid;
+    V9fsFidState *next;
+};
+
+typedef struct V9fsState
+{
+    VirtIODevice vdev;
+    VirtQueue *vq;
+    V9fsPDU pdus[MAX_REQ];
+    QLIST_HEAD(, V9fsPDU) free_list;
+    V9fsFidState *fid_list;
+    FileOperations *ops;
+    FsContext ctx;
+    uint16_t tag_len;
+    uint8_t *tag;
+    size_t config_size;
+} V9fsState;
+
+struct virtio_9p_config
+{
+    /* number of characters in tag */
+    uint16_t tag_len;
+    /* Variable size tag name */
+    uint8_t tag[0];
+} __attribute__((packed));
+
+extern size_t pdu_packunpack(void *addr, struct iovec *sg, int sg_count,
+                            size_t offset, size_t size, int pack);
+
+static inline size_t do_pdu_unpack(void *dst, struct iovec *sg, int sg_count,
+                        size_t offset, size_t size)
+{
+    return pdu_packunpack(dst, sg, sg_count, offset, size, 0);
+}
+
+#endif
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 7ce526f..7ddf612 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -102,6 +102,9 @@ typedef struct {
     BlockConf block;
     NICConf nic;
     uint32_t host_features;
+#ifdef CONFIG_LINUX
+    V9fsConf fsconf;
+#endif
     /* Max. number of ports we can have for a the virtio-serial device */
     uint32_t max_virtserial_ports;
 } VirtIOPCIProxy;
@@ -639,6 +642,23 @@ static int virtio_balloon_init_pci(PCIDevice *pci_dev)
     return 0;
 }
 
+#ifdef CONFIG_LINUX
+static int virtio_9p_init_pci(PCIDevice *pci_dev)
+{
+    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+    VirtIODevice *vdev;
+
+    vdev = virtio_9p_init(&pci_dev->qdev, &proxy->fsconf);
+    virtio_init_pci(proxy, vdev,
+                    PCI_VENDOR_ID_REDHAT_QUMRANET,
+                    0x1009,
+                    0x2,
+                    0x00);
+
+    return 0;
+}
+#endif
+
 static PCIDeviceInfo virtio_info[] = {
     {
         .qdev.name = "virtio-blk-pci",
@@ -693,6 +713,18 @@ static PCIDeviceInfo virtio_info[] = {
         },
         .qdev.reset = virtio_pci_reset,
     },{
+#ifdef CONFIG_LINUX
+        .qdev.name = "virtio-9p-pci",
+        .qdev.size = sizeof(VirtIOPCIProxy),
+        .init      = virtio_9p_init_pci,
+        .qdev.props = (Property[]) {
+            DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
+            DEFINE_PROP_STRING("mount_tag", VirtIOPCIProxy, fsconf.tag),
+            DEFINE_PROP_STRING("fsdev", VirtIOPCIProxy, fsconf.fsdev_id),
+            DEFINE_PROP_END_OF_LIST(),
+        },
+    }, {
+#endif
         /* end of list */
     }
 };
diff --git a/hw/virtio.h b/hw/virtio.h
index f885f1b..e4306cd 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -20,6 +20,9 @@
 #include "sysemu.h"
 #include "block_int.h"
 #include "event_notifier.h"
+#ifdef CONFIG_LINUX
+#include "9p.h"
+#endif
 
 /* from Linux's linux/virtio_config.h */
 
@@ -185,6 +188,10 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf);
 VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf);
 VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports);
 VirtIODevice *virtio_balloon_init(DeviceState *dev);
+#ifdef CONFIG_LINUX
+VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf);
+#endif
+
 
 void virtio_net_exit(VirtIODevice *vdev);