[PATCH 7/7] qemu:virtio-net: Add VLAN filtering

Alex Williamson
2009-01-20T21:38:05Z

Use the control virtqueue to allow the guest to enable and manipulate
a VLAN filter table. This allows us to drop more packets the guest
doesn't want to see. We define a new VLAN class for the control
virtqueue with commands ENABLE, ADD, and DEL with usage defined in
virtio-net.h. By default VLAN filtering is disabled to allow backwards
compatibility with guest drivers.

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

Updated to reflect VLAN_KILL -> VLAN_DEL rename in the guest driver
Updated to reflect change in receive_filter() looking past vnet_hdr.

qemu/hw/virtio-net.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++-
qemu/hw/virtio-net.h | 15 +++++++++++
2 files changed, 84 insertions(+), 1 deletions(-)

diff --git a/qemu/hw/virtio-net.c b/qemu/hw/virtio-net.c
index 528171e..8f3c41d 100644
--- a/qemu/hw/virtio-net.c
+++ b/qemu/hw/virtio-net.c
@@ -21,9 +21,10 @@

#define TAP_VNET_HDR

-#define VIRTIO_NET_VM_VERSION 5
+#define VIRTIO_NET_VM_VERSION 6

#define ETH_ALEN 6
+#define MAX_VLAN (1 << 12) /* Per 802.1Q definition */

typedef struct VirtIONet
{
@@ -44,6 +45,10 @@ typedef struct VirtIONet
int in_use;
uint8_t *macs;
} mac_table;
+ struct {
+ int enabled;
+ uint32_t *vlans;
+ } vlan_table;
} VirtIONet;

/* TODO
@@ -101,6 +106,9 @@ static void virtio_net_reset(VirtIODevice *vdev)
n->mac_table.entries = 0;
qemu_free(n->mac_table.macs);
n->mac_table.macs = NULL;
+
+ n->vlan_table.enabled = 0;
+ memset(n->vlan_table.vlans, 0, MAX_VLAN >> 3);
}

static uint32_t virtio_net_get_features(VirtIODevice *vdev)
@@ -223,6 +231,45 @@ static int virtio_net_handle_mac_table(VirtIONet *n, uint8_t cmd,
return VIRTIO_NET_ERR;
}

+static int virtio_net_handle_vlan_table(VirtIONet *n, uint8_t cmd,
+ VirtQueueElement *elem)
+{
+ uint16_t *vid;
+
+ if (cmd == VIRTIO_NET_CTRL_VLAN_ENABLE) {
+ uint8_t *on;
+
+ if (elem->out_num != 2 || elem->out_sg[1].iov_len != sizeof(*on)) {
+ fprintf(stderr, "virtio-net ctrl invalid vlan command\n");
+ exit(1);
+ }
+
+ on = elem->out_sg[1].iov_base;
+
+ n->vlan_table.enabled = *on;
+ return VIRTIO_NET_OK;
+ }
+
+ if (elem->out_num != 2 || elem->out_sg[1].iov_len != sizeof(*vid)) {
+ fprintf(stderr, "virtio-net ctrl invalid vlan command\n");
+ exit(1);
+ }
+
+ vid = elem->out_sg[1].iov_base;
+
+ if (*vid >= MAX_VLAN)
+ return VIRTIO_NET_ERR;
+
+ if (cmd == VIRTIO_NET_CTRL_VLAN_ADD)
+ n->vlan_table.vlans[*vid >> 5] |= (1U << (*vid & 0x1f));
+ else if (cmd == VIRTIO_NET_CTRL_VLAN_DEL)
+ n->vlan_table.vlans[*vid >> 5] &= ~(1U << (*vid & 0x1f));
+ else
+ return VIRTIO_NET_ERR;
+
+ return VIRTIO_NET_OK;
+}
+
static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIONet *n = to_virtio_net(vdev);
@@ -250,6 +297,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
*status = virtio_net_handle_rx_mode(n, ctrl->cmd, &elem);
else if (ctrl->class == VIRTIO_NET_CTRL_MAC_TABLE)
*status = virtio_net_handle_mac_table(n, ctrl->cmd, &elem);
+ else if (ctrl->class == VIRTIO_NET_CTRL_VLAN)
+ *status = virtio_net_handle_vlan_table(n, ctrl->cmd, &elem);

virtqueue_push(vq, &elem, sizeof(*status));
virtio_notify(vdev, vq);
@@ -366,6 +415,7 @@ static int receive_header(VirtIONet *n, struct iovec *iov, int iovcnt,
static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
{
static uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+ static uint8_t vlan[] = {0x81, 0x00};
uint8_t *ptr = (uint8_t *)buf;
int i;

@@ -374,6 +424,12 @@ static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
ptr += sizeof(struct virtio_net_hdr);
#endif

+ if (n->vlan_table.enabled && !memcmp(&ptr[12], vlan, sizeof(vlan))) {
+ int vid = be16_to_cpup((uint16_t *)(ptr + 14)) & 0xfff;
+ if (!(n->vlan_table.vlans[vid >> 5] & (1U << (vid & 0x1f))))
+ return 0;
+ }
+
if (n->promisc)
return 1;

@@ -573,6 +629,8 @@ static void virtio_net_save(QEMUFile *f, void *opaque)
qemu_put_be32(f, n->mac_table.in_use);
if (n->mac_table.entries)
qemu_put_buffer(f, n->mac_table.macs, n->mac_table.entries * ETH_ALEN);
+ qemu_put_be32(f, n->vlan_table.enabled);
+ qemu_put_buffer(f, (uint8_t *)n->vlan_table.vlans, MAX_VLAN >> 3);
}

static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
@@ -614,6 +672,11 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
}
}

+ if (version_id >= 6) {
+ n->vlan_table.enabled = qemu_get_be32(f);
+ qemu_get_buffer(f, (uint8_t *)n->vlan_table.vlans, MAX_VLAN >> 3);
+ }
+
if (n->tx_timer_active) {
qemu_mod_timer(n->tx_timer,
qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
@@ -656,6 +719,11 @@ PCIDevice *virtio_net_init(PCIBus *bus, NICInfo *nd, int devfn)
n->mergeable_rx_bufs = 0;
n->promisc = 1; /* for compatibility */

+ /* VLAN filter table starts disabled for compatibility */
+ n->vlan_table.vlans = qemu_mallocz(MAX_VLAN >> 3);
+ if (!n->vlan_table.vlans)
+ return NULL;
+
register_savevm("virtio-net", virtio_net_id++, VIRTIO_NET_VM_VERSION,
virtio_net_save, virtio_net_load, n);

diff --git a/qemu/hw/virtio-net.h b/qemu/hw/virtio-net.h
index 6faf497..bf40207 100644
--- a/qemu/hw/virtio-net.h
+++ b/qemu/hw/virtio-net.h
@@ -128,4 +128,19 @@ typedef uint8_t virtio_net_ctrl_ack;
#define VIRTIO_NET_CTRL_MAC_TABLE_ALLOC 0
#define VIRTIO_NET_CTRL_MAC_TABLE_SET 1

+/*
+ * Control VLAN filtering
+ *
+ * The VLAN filter table is controlled via a simple ADD/DEL interface.
+ * VLAN IDs not added will be dropped. Del is the opposite of add.
+ * Both commands expect an out entry containing a 2 byte VLAN ID.
+ * The ENABLE command expects an out entry containing a single byte,
+ * zero to disable, non-zero to enable. The default state is disabled
+ * for compatibility.
+ */
+#define VIRTIO_NET_CTRL_VLAN 2
+ #define VIRTIO_NET_CTRL_VLAN_ENABLE 0
+ #define VIRTIO_NET_CTRL_VLAN_ADD 1
+ #define VIRTIO_NET_CTRL_VLAN_DEL 2
+
#endif