Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 201 insertions, 0 deletions

diff --git a/net/filter-buffer.c b/net/filter-buffer.c
new file mode 100644
index 000000000..283dc9cbe
--- /dev/null
+++ b/net/filter-buffer.c
@@ -0,0 +1,201 @@
+/*
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Author: Yang Hongyang <yanghy@cn.fujitsu.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "net/filter.h"
+#include "net/queue.h"
+#include "qapi/error.h"
+#include "qemu/timer.h"
+#include "qemu/iov.h"
+#include "qapi/qapi-builtin-visit.h"
+#include "qapi/qmp/qerror.h"
+#include "qom/object.h"
+
+#define TYPE_FILTER_BUFFER "filter-buffer"
+
+OBJECT_DECLARE_SIMPLE_TYPE(FilterBufferState, FILTER_BUFFER)
+
+struct FilterBufferState {
+    NetFilterState parent_obj;
+
+    NetQueue *incoming_queue;
+    uint32_t interval;
+    QEMUTimer release_timer;
+};
+
+static void filter_buffer_flush(NetFilterState *nf)
+{
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    if (!qemu_net_queue_flush(s->incoming_queue)) {
+        /* Unable to empty the queue, purge remaining packets */
+        qemu_net_queue_purge(s->incoming_queue, nf->netdev);
+    }
+}
+
+static void filter_buffer_release_timer(void *opaque)
+{
+    NetFilterState *nf = opaque;
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    /*
+     * Note: filter_buffer_flush() drops packets that can't be sent
+     * TODO: We should leave them queued.  But currently there's no way
+     * for the next filter or receiver to notify us that it can receive
+     * more packets.
+     */
+    filter_buffer_flush(nf);
+    /* Timer rearmed to fire again in s->interval microseconds. */
+    timer_mod(&s->release_timer,
+              qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) + s->interval);
+}
+
+/* filter APIs */
+static ssize_t filter_buffer_receive_iov(NetFilterState *nf,
+                                         NetClientState *sender,
+                                         unsigned flags,
+                                         const struct iovec *iov,
+                                         int iovcnt,
+                                         NetPacketSent *sent_cb)
+{
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    /*
+     * We return size when buffer a packet, the sender will take it as
+     * a already sent packet, so sent_cb should not be called later.
+     *
+     * FIXME: Even if the guest can't receive packets for some reasons,
+     * the filter can still accept packets until its internal queue is full.
+     * For example:
+     *   For some reason, receiver could not receive more packets
+     * (.can_receive() returns false). Without a filter, at most one packet
+     * will be queued in incoming queue and sender's poll will be disabled
+     * unit its sent_cb() was called. With a filter, it will keep receiving
+     * the packets without caring about the receiver. This is suboptimal.
+     * May need more thoughts (e.g keeping sent_cb).
+     */
+    qemu_net_queue_append_iov(s->incoming_queue, sender, flags,
+                              iov, iovcnt, NULL);
+    return iov_size(iov, iovcnt);
+}
+
+static void filter_buffer_cleanup(NetFilterState *nf)
+{
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    if (s->interval) {
+        timer_del(&s->release_timer);
+    }
+
+    /* flush packets */
+    if (s->incoming_queue) {
+        filter_buffer_flush(nf);
+        g_free(s->incoming_queue);
+    }
+}
+
+static void filter_buffer_setup_timer(NetFilterState *nf)
+{
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    if (s->interval) {
+        timer_init_us(&s->release_timer, QEMU_CLOCK_VIRTUAL,
+                      filter_buffer_release_timer, nf);
+        /* Timer armed to fire in s->interval microseconds. */
+        timer_mod(&s->release_timer,
+                  qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) + s->interval);
+    }
+}
+
+static void filter_buffer_setup(NetFilterState *nf, Error **errp)
+{
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    /*
+     * We may want to accept zero interval when VM FT solutions like MC
+     * or COLO use this filter to release packets on demand.
+     */
+    if (!s->interval) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "interval",
+                   "a non-zero interval");
+        return;
+    }
+
+    s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
+    filter_buffer_setup_timer(nf);
+}
+
+static void filter_buffer_status_changed(NetFilterState *nf, Error **errp)
+{
+    FilterBufferState *s = FILTER_BUFFER(nf);
+
+    if (!nf->on) {
+        if (s->interval) {
+            timer_del(&s->release_timer);
+        }
+        filter_buffer_flush(nf);
+    } else {
+        filter_buffer_setup_timer(nf);
+    }
+}
+
+static void filter_buffer_get_interval(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    FilterBufferState *s = FILTER_BUFFER(obj);
+    uint32_t value = s->interval;
+
+    visit_type_uint32(v, name, &value, errp);
+}
+
+static void filter_buffer_set_interval(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    FilterBufferState *s = FILTER_BUFFER(obj);
+    uint32_t value;
+
+    if (!visit_type_uint32(v, name, &value, errp)) {
+        return;
+    }
+    if (!value) {
+        error_setg(errp, "Property '%s.%s' requires a positive value",
+                   object_get_typename(obj), name);
+        return;
+    }
+    s->interval = value;
+}
+
+static void filter_buffer_class_init(ObjectClass *oc, void *data)
+{
+    NetFilterClass *nfc = NETFILTER_CLASS(oc);
+
+    object_class_property_add(oc, "interval", "uint32",
+                              filter_buffer_get_interval,
+                              filter_buffer_set_interval, NULL, NULL);
+
+    nfc->setup = filter_buffer_setup;
+    nfc->cleanup = filter_buffer_cleanup;
+    nfc->receive_iov = filter_buffer_receive_iov;
+    nfc->status_changed = filter_buffer_status_changed;
+}
+
+static const TypeInfo filter_buffer_info = {
+    .name = TYPE_FILTER_BUFFER,
+    .parent = TYPE_NETFILTER,
+    .class_init = filter_buffer_class_init,
+    .instance_size = sizeof(FilterBufferState),
+};
+
+static void register_types(void)
+{
+    type_register_static(&filter_buffer_info);
+}
+
+type_init(register_types);