[Qemu-devel] [PATCH v2 7/8] qemu:virtio-net: Add additional MACs via a filter table

[Alex Williamson <alex.williamson@hp.com>]

Create a filter table and allow the guest to populate it with the
MAC class control commands.  We manage the size and usage of the
filter table including enabling promiscuous and all-multi modes
as necessary.  The guest should therefore assume the table is
infinite.  Eventually this might allow us to bind directly to a
hardware NIC and manipulate a physical MAC filter.

The specifics of the TABLE_SET command are documented in
virtio-net.h.  Separate buffers in the same command are used
for unicaste and multicast addresses for priority and
sychronization.  With this we can export the VIRTIO_NET_F_CTRL_RX
feature bit.

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

 hw/virtio-net.c |   88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 hw/virtio-net.h |   22 ++++++++++++++
 2 files changed, 108 insertions(+), 2 deletions(-)

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index d01da22..40050ff 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -16,7 +16,9 @@
 #include "qemu-timer.h"
 #include "virtio-net.h"
 
-#define VIRTIO_NET_VM_VERSION    4
+#define VIRTIO_NET_VM_VERSION    5
+
+#define MAC_TABLE_ENTRIES    32
 
 typedef struct VirtIONet
 {
@@ -32,6 +34,10 @@ typedef struct VirtIONet
     int mergeable_rx_bufs;
     int promisc;
     int allmulti;
+    struct {
+        int in_use;
+        uint8_t *macs;
+    } mac_table;
 } VirtIONet;
 
 /* TODO
@@ -87,13 +93,18 @@ static void virtio_net_reset(VirtIODevice *vdev)
     /* Reset back to compatibility mode */
     n->promisc = 1;
     n->allmulti = 0;
+
+    /* Flush any MAC filter table state */
+    n->mac_table.in_use = 0;
+    memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
 }
 
 static uint32_t virtio_net_get_features(VirtIODevice *vdev)
 {
     uint32_t features = (1 << VIRTIO_NET_F_MAC) |
                         (1 << VIRTIO_NET_F_STATUS) |
-                        (1 << VIRTIO_NET_F_CTRL_VQ);
+                        (1 << VIRTIO_NET_F_CTRL_VQ) |
+                        (1 << VIRTIO_NET_F_CTRL_RX);
 
     return features;
 }
@@ -127,6 +138,52 @@ static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
     return VIRTIO_NET_OK;
 }
 
+static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
+                                 VirtQueueElement *elem)
+{
+    struct virtio_net_ctrl_mac *mac_data;
+
+    if (cmd != VIRTIO_NET_CTRL_MAC_TABLE_SET || elem->out_num != 3 ||
+        elem->out_sg[1].iov_len < sizeof(mac_data->entries) ||
+        elem->out_sg[2].iov_len < sizeof(mac_data->entries))
+        return VIRTIO_NET_ERR;
+
+    n->mac_table.in_use = 0;
+    memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
+
+    mac_data = (void *)elem->out_sg[1].iov_base;
+
+    if (sizeof(mac_data->entries) +
+        (mac_data->entries * ETH_ALEN) > elem->out_sg[1].iov_len)
+        return VIRTIO_NET_ERR;
+
+    if (mac_data->entries <= MAC_TABLE_ENTRIES) {
+        memcpy(n->mac_table.macs, &mac_data->macs,
+               mac_data->entries * ETH_ALEN);
+        n->mac_table.in_use += mac_data->entries;
+    } else {
+        n->promisc = 1;
+        return VIRTIO_NET_OK;
+    }
+
+    mac_data = (void *)elem->out_sg[2].iov_base;
+
+    if (sizeof(mac_data->entries) +
+        (mac_data->entries * ETH_ALEN) > elem->out_sg[2].iov_len)
+        return VIRTIO_NET_ERR;
+
+    if (mac_data->entries) {
+        if (n->mac_table.in_use + mac_data->entries <= MAC_TABLE_ENTRIES) {
+            memcpy(n->mac_table.macs + (n->mac_table.in_use * ETH_ALEN),
+                   &mac_data->macs, mac_data->entries * ETH_ALEN);
+            n->mac_table.in_use += mac_data->entries;
+        } else
+            n->allmulti = 1;
+    }
+
+    return VIRTIO_NET_OK;
+}
+
 static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIONet *n = to_virtio_net(vdev);
@@ -152,6 +209,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 
         if (ctrl->class == VIRTIO_NET_CTRL_RX_MODE)
             *status = virtio_net_handle_rx_mode(n, ctrl->cmd, &elem);
+        else if (ctrl->class == VIRTIO_NET_CTRL_MAC)
+            *status = virtio_net_handle_mac(n, ctrl->cmd, &elem);
 
         virtqueue_push(vq, &elem, sizeof(*status));
         virtio_notify(vdev, vq);
@@ -225,6 +284,7 @@ static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
 {
     static uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
     uint8_t *ptr = (uint8_t *)buf;
+    int i;
 
     if (n->promisc)
         return 1;
@@ -243,6 +303,11 @@ static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
     if (!memcmp(ptr, n->mac, ETH_ALEN))
         return 1;
 
+    for (i = 0; i < n->mac_table.in_use; i++) {
+        if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN))
+            return 1;
+    }
+
     return 0;
 }
 
@@ -405,6 +470,8 @@ static void virtio_net_save(QEMUFile *f, void *opaque)
     qemu_put_be16(f, n->status);
     qemu_put_be32(f, n->promisc);
     qemu_put_be32(f, n->allmulti);
+    qemu_put_be32(f, n->mac_table.in_use);
+    qemu_put_buffer(f, n->mac_table.macs, n->mac_table.in_use * ETH_ALEN);
 }
 
 static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
@@ -428,6 +495,19 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
         n->allmulti = qemu_get_be32(f);
     }
 
+    if (version_id >= 5) {
+        n->mac_table.in_use = qemu_get_be32(f);
+        /* MAC_TABLE_ENTRIES may be different from the saved image */
+        if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) {
+            qemu_get_buffer(f, n->mac_table.macs,
+                            n->mac_table.in_use * ETH_ALEN);
+        } else if (n->mac_table.in_use) {
+            qemu_fseek(f, n->mac_table.in_use * ETH_ALEN, SEEK_CUR);
+            n->promisc = 1;
+            n->mac_table.in_use = 0;
+        }
+    }
+ 
     if (n->tx_timer_active) {
         qemu_mod_timer(n->tx_timer,
                        qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
@@ -473,6 +553,10 @@ void virtio_net_init(PCIBus *bus, NICInfo *nd, int devfn)
     n->mergeable_rx_bufs = 0;
     n->promisc = 1; /* for compatibility */
 
+    n->mac_table.macs = qemu_mallocz(MAC_TABLE_ENTRIES * ETH_ALEN);
+    if (!n->mac_table.macs)
+        return;
+
     register_savevm("virtio-net", virtio_net_id++, VIRTIO_NET_VM_VERSION,
                     virtio_net_save, virtio_net_load, n);
 }
diff --git a/hw/virtio-net.h b/hw/virtio-net.h
index ce8e4b4..291fa9d 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -113,4 +113,26 @@ typedef uint8_t virtio_net_ctrl_ack;
  #define VIRTIO_NET_CTRL_RX_MODE_PROMISC      0
  #define VIRTIO_NET_CTRL_RX_MODE_ALLMULTI     1
 
+/*
+ * Control the MAC filter table.
+ *
+ * The MAC filter table is managed by the hypervisor, the guest should
+ * assume the size is infinite.  Filtering should be considered
+ * non-perfect, ie. based on hypervisor resources, the guest may
+ * received packets from sources not specified in the filter list.
+ *
+ * In addition to the class/cmd header, the TABLE_SET command requires
+ * two out scatterlists.  Each contains a 4 byte count of entries followed
+ * by a concatenated byte stream of the ETH_ALEN MAC addresses.  The
+ * first sg list contains unicast addresses, the second is for multicast.
+ * This functionality is present if the VIRTIO_NET_F_CTRL_RX feature
+ * is available.
+ */
+struct virtio_net_ctrl_mac {
+    uint32_t entries;
+    uint8_t macs[][ETH_ALEN];
+};
+#define VIRTIO_NET_CTRL_MAC    1
+ #define VIRTIO_NET_CTRL_MAC_TABLE_SET        0
+
 #endif