[Qemu-devel] [PATCH 13/21] xen/9pfs: connect to the frontend

[Stefano Stabellini <sstabellini@kernel.org>]

Write the limits of the backend to xenstore. Connect to the frontend.
Upon connection, allocate the rings according to the protocol
specification.

Initialize a QEMUBH to schedule work upon receiving an event channel
notification from the frontend.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: anthony.perard@citrix.com
CC: jgross@suse.com
CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
CC: Greg Kurz <groug@kaod.org>
---
 hw/9pfs/xen-9p-backend.c | 182 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 181 insertions(+), 1 deletion(-)

diff --git a/hw/9pfs/xen-9p-backend.c b/hw/9pfs/xen-9p-backend.c
index da8ae18..03dd881 100644
--- a/hw/9pfs/xen-9p-backend.c
+++ b/hw/9pfs/xen-9p-backend.c
@@ -17,8 +17,41 @@
 #include "qemu/config-file.h"
 #include "fsdev/qemu-fsdev.h"
 
+#define VERSIONS "1"
+#define MAX_RINGS 8
+#define MAX_RING_ORDER 8
+
+typedef struct Xen9pfsRing {
+    struct Xen9pfsDev *priv;
+
+    int ref;
+    xenevtchn_handle   *evtchndev;
+    int evtchn;
+    int local_port;
+    int ring_order;
+    struct xen_9pfs_data_intf *intf;
+    unsigned char *data;
+    struct xen_9pfs_data ring;
+
+    struct iovec *sg;
+    QEMUBH *bh;
+
+    /* local copies, so that we can read/write PDU data directly from
+     * the ring */
+    RING_IDX out_cons, out_size, in_cons;
+    bool inprogress;
+} Xen9pfsRing;
+
 typedef struct Xen9pfsDev {
     struct XenDevice xendev;  /* must be first */
+    V9fsState state;
+    char *path;
+    char *security_model;
+    char *tag;
+    char *id;
+
+    int num_rings;
+    Xen9pfsRing *rings;
 } Xen9pfsDev;
 
 static ssize_t xen_9pfs_pdu_vmarshal(V9fsPDU *pdu,
@@ -67,22 +100,169 @@ static int xen_9pfs_init(struct XenDevice *xendev)
     return 0;
 }
 
+static void xen_9pfs_bh(void *opaque)
+{
+}
+
+static void xen_9pfs_evtchn_event(void *opaque)
+{
+}
+
 static int xen_9pfs_free(struct XenDevice *xendev)
 {
-    return -1;
+    int i;
+    Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
+
+    g_free(xen_9pdev->id);
+    g_free(xen_9pdev->tag);
+    g_free(xen_9pdev->path);
+    g_free(xen_9pdev->security_model);
+
+    for (i = 0; i < xen_9pdev->num_rings; i++) {
+        if (xen_9pdev->rings[i].data != NULL) {
+            xengnttab_unmap(xen_9pdev->xendev.gnttabdev,
+                    xen_9pdev->rings[i].data,
+                    (1 << xen_9pdev->rings[i].ring_order));
+        }
+        if (xen_9pdev->rings[i].intf != NULL) {
+            xengnttab_unmap(xen_9pdev->xendev.gnttabdev,
+                    xen_9pdev->rings[i].intf,
+                    1);
+        }
+        if (xen_9pdev->rings[i].evtchndev > 0) {
+            qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
+                    NULL, NULL, NULL);
+            xenevtchn_unbind(xen_9pdev->rings[i].evtchndev,
+                             xen_9pdev->rings[i].local_port);
+        }
+        if (xen_9pdev->rings[i].bh != NULL) {
+            qemu_bh_delete(xen_9pdev->rings[i].bh);
+        }
+    }
+    g_free(xen_9pdev->rings);
+    return 0;
 }
 
 static int xen_9pfs_connect(struct XenDevice *xendev)
 {
+    int i;
+    Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
+    V9fsState *s = &xen_9pdev->state;
+    QemuOpts *fsdev;
+
+    if (xenstore_read_fe_int(&xen_9pdev->xendev, "num-rings",
+                             &xen_9pdev->num_rings) == -1 ||
+        xen_9pdev->num_rings > MAX_RINGS || xen_9pdev->num_rings < 1) {
+        return -1;
+    }
+
+    xen_9pdev->rings = g_malloc0(xen_9pdev->num_rings * sizeof(Xen9pfsRing));
+    for (i = 0; i < xen_9pdev->num_rings; i++) {
+        char *str;
+        int ring_order;
+
+        xen_9pdev->rings[i].priv = xen_9pdev;
+        xen_9pdev->rings[i].evtchn = -1;
+        xen_9pdev->rings[i].local_port = -1;
+
+        str = g_strdup_printf("ring-ref%u", i);
+        if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
+                                 &xen_9pdev->rings[i].ref) == -1) {
+            goto out;
+        }
+        g_free(str);
+        str = g_strdup_printf("event-channel-%u", i);
+        if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
+                                 &xen_9pdev->rings[i].evtchn) == -1) {
+            goto out;
+        }
+        g_free(str);
+
+        xen_9pdev->rings[i].intf =  xengnttab_map_grant_ref(
+                xen_9pdev->xendev.gnttabdev,
+                xen_9pdev->xendev.dom,
+                xen_9pdev->rings[i].ref,
+                PROT_READ | PROT_WRITE);
+        if (!xen_9pdev->rings[i].intf) {
+            goto out;
+        }
+        ring_order = xen_9pdev->rings[i].intf->ring_order;
+        if (ring_order > MAX_RING_ORDER) {
+            goto out;
+        }
+        xen_9pdev->rings[i].ring_order = ring_order;
+        xen_9pdev->rings[i].data = xengnttab_map_domain_grant_refs(
+                xen_9pdev->xendev.gnttabdev,
+                (1 << ring_order),
+                xen_9pdev->xendev.dom,
+                xen_9pdev->rings[i].intf->ref,
+                PROT_READ | PROT_WRITE);
+        if (!xen_9pdev->rings[i].data) {
+            goto out;
+        }
+        xen_9pdev->rings[i].ring.in = xen_9pdev->rings[i].data;
+        xen_9pdev->rings[i].ring.out = xen_9pdev->rings[i].data +
+                                       XEN_FLEX_RING_SIZE(ring_order);
+
+        xen_9pdev->rings[i].bh = qemu_bh_new(xen_9pfs_bh, &xen_9pdev->rings[i]);
+        xen_9pdev->rings[i].out_cons = 0;
+        xen_9pdev->rings[i].out_size = 0;
+        xen_9pdev->rings[i].inprogress = false;
+
+
+        xen_9pdev->rings[i].evtchndev = xenevtchn_open(NULL, 0);
+        if (xen_9pdev->rings[i].evtchndev == NULL) {
+            goto out;
+        }
+        fcntl(xenevtchn_fd(xen_9pdev->rings[i].evtchndev), F_SETFD, FD_CLOEXEC);
+        xen_9pdev->rings[i].local_port = xenevtchn_bind_interdomain
+                                            (xen_9pdev->rings[i].evtchndev,
+                                             xendev->dom,
+                                             xen_9pdev->rings[i].evtchn);
+        if (xen_9pdev->rings[i].local_port == -1) {
+            xen_pv_printf(xendev, 0,
+                          "xenevtchn_bind_interdomain failed port=%d\n",
+                          xen_9pdev->rings[i].evtchn);
+            goto out;
+        }
+        xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
+        qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
+                xen_9pfs_evtchn_event, NULL, &xen_9pdev->rings[i]);
+    }
+
+    xen_9pdev->security_model = xenstore_read_be_str(xendev, "security_model");
+    xen_9pdev->path = xenstore_read_be_str(xendev, "path");
+    xen_9pdev->id = s->fsconf.fsdev_id =
+        g_strdup_printf("xen9p%d", xendev->dev);
+    xen_9pdev->tag = s->fsconf.tag = xenstore_read_fe_str(xendev, "tag");
+    v9fs_register_transport(s, &xen_9p_transport);
+    fsdev = qemu_opts_create(qemu_find_opts("fsdev"),
+            s->fsconf.tag,
+            1, NULL);
+    qemu_opt_set(fsdev, "fsdriver", "local", NULL);
+    qemu_opt_set(fsdev, "path", xen_9pdev->path, NULL);
+    qemu_opt_set(fsdev, "security_model", xen_9pdev->security_model, NULL);
+    qemu_opts_set_id(fsdev, s->fsconf.fsdev_id);
+    qemu_fsdev_add(fsdev);
+    v9fs_device_realize_common(s, NULL);
+
     return 0;
+
+out:
+    xen_9pfs_free(xendev);
+    return -1;
 }
 
 static void xen_9pfs_alloc(struct XenDevice *xendev)
 {
+    xenstore_write_be_str(xendev, "versions", VERSIONS);
+    xenstore_write_be_int(xendev, "max-rings", MAX_RINGS);
+    xenstore_write_be_int(xendev, "max-ring-page-order", MAX_RING_ORDER);
 }
 
 static void xen_9pfs_disconnect(struct XenDevice *xendev)
 {
+    /* Dynamic hotplug of PV filesystems at runtime is not supported. */
 }
 
 struct XenDevOps xen_9pfs_ops = {
-- 
1.9.1