[PATCH 1/4] qemu:net: Add infrastructure for setting an RX filter through the vlan

Alex Williamson
2009-02-10T21:31:05Z

Some interfaces, such as tap, can set a filter to prevent unwanted
packets from interrupting qemu. This patch adds infrastructure for
vlan clients to request a set of filtering parameters. The main
client interface for this is the new qemu_vlan_rxfilter() function.
For simplicity, we restrict the topology that can make use of a filter
to exactly two clients on a vlan. To handle hotplug devices, we add
vlan_client_added/removed notifiers which can automatically revert
back to a shared media protocol. Devices providing filtering can do
so via the new fd_rxfilter() interface.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
---

net.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
net.h | 14 ++++++++++++++
2 files changed, 56 insertions(+), 1 deletions(-)

diff --git a/net.c b/net.c
index e7c097e..e68cb40 100644
--- a/net.c
+++ b/net.c
@@ -345,8 +345,11 @@ VLANClientState *qemu_new_vlan_client(VLANState *vlan,

vc->next = NULL;
pvc = &vlan->first_client;
- while (*pvc != NULL)
+ while (*pvc != NULL) {
+ if ((*pvc)->vlan_client_added)
+ (*pvc)->vlan_client_added((*pvc)->opaque);
pvc = &(*pvc)->next;
+ }
*pvc = vc;
return vc;
}
@@ -364,6 +367,12 @@ void qemu_del_vlan_client(VLANClientState *vc)
break;
} else
pvc = &(*pvc)->next;
+
+ /* Notify other clients after removal for dependencies on new topology */
+ pvc = &vc->vlan->first_client;
+ while (*pvc != NULL)
+ if ((*pvc)->vlan_client_removed)
+ (*pvc)->vlan_client_removed((*pvc)->opaque);
}

int qemu_can_send_packet(VLANClientState *vc1)
@@ -458,6 +467,38 @@ ssize_t qemu_sendv_packet(VLANClientState *vc1, const struct iovec *iov,
return max_len;
}

+/*
+ * This function allows a qemu vlan client to request filtering on
+ * it's receiving interface. We only use this for the typical case
+ * of having exactly two clients on the vlan. Clients making use
+ * of this function should also implement a vlan_client_added()
+ * function to be notified when they need to fall back to their own
+ * filtering or disable filtering setup for a single consumer.
+ *
+ * A return value of 1 indicates the entire requested filter set
+ * is handled by the provided filter.
+ */
+int qemu_vlan_rxfilter(VLANClientState *vc1, int flags, int count,
+ uint8_t *buf)
+{
+ VLANState *vlan = vc1->vlan;
+ VLANClientState *vc;
+
+ if (vlan->first_client == NULL || vlan->first_client->next == NULL ||
+ vlan->first_client->next->next != NULL)
+ return 0;
+
+ if (vlan->first_client == vc1)
+ vc = vc1->next;
+ else
+ vc = vlan->first_client;
+
+ if (vc->fd_rxfilter)
+ return (vc->fd_rxfilter(vc->opaque, flags, count, buf) == count);
+
+ return 0;
+}
+
#if defined(CONFIG_SLIRP)

/* slirp network adapter */
diff --git a/net.h b/net.h
index 291807a..2090111 100644
--- a/net.h
+++ b/net.h
@@ -11,13 +11,22 @@ typedef struct VLANClientState VLANClientState;

typedef void (LinkStatusChanged)(VLANClientState *);

+typedef int (IORXFilter)(void *, unsigned int , int , uint8_t *);
+
+typedef void (VLANClientAdded)(void *);
+
+typedef void (VLANClientRemoved)(void *);
+
struct VLANClientState {
IOReadHandler *fd_read;
IOReadvHandler *fd_readv;
/* Packets may still be sent if this returns zero. It's used to
rate-limit the slirp code. */
IOCanRWHandler *fd_can_read;
+ IORXFilter *fd_rxfilter;
LinkStatusChanged *link_status_changed;
+ VLANClientAdded *vlan_client_added;
+ VLANClientRemoved *vlan_client_removed;
int link_down;
void *opaque;
struct VLANClientState *next;
@@ -51,10 +60,15 @@ void qemu_check_nic_model(NICInfo *nd, const char *model);
void qemu_check_nic_model_list(NICInfo *nd, const char * const *models,
const char *default_model);
void qemu_handler_true(void *opaque);
+int qemu_vlan_rxfilter(VLANClientState *vc1, int flags, int count,
+ uint8_t *buf);

void do_info_network(void);
int do_set_link(const char *name, const char *up_or_down);

+#define QEMU_NET_PROMISC 1
+#define QEMU_NET_ALLMULTI 2
+
/* NIC info */

#define MAX_NICS 8