virtio-net: MAC filter optimization

The MAC filter table is received from the guest as two separate buffers, one with unicast entries, the other with multicast entries. If we track the index dividing the two sets, we can avoid searching the part of the table with the wrong type of entries. We could store this index as part of the save image, but its trivially easy to discover it on load. Signed-off-by: Alex Williamson <alex.williamson@hp.com> Signed-off-by: Mark McLoughlin <markmc@redhat.com>

virtio-net: MAC filter optimization
The MAC filter table is received from the guest as two separate buffers, one with unicast entries, the other with multicast entries. If we track the index dividing the two sets, we can avoid searching the part of the table with the wrong type of entries. We could store this index as part of the save image, but its trivially easy to discover it on load. Signed-off-by: Alex Williamson <alex.williamson@hp.com> Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Alex Williamson · Mark McLoughlin
1 parent 8fd2a2f1
Showing 1 changed file with 25 additions and 4 deletions
hw/virtio-net.c
@@ -37,6 +37,7 @@ typedef struct VirtIONet
     uint8_t allmulti;
     struct {
         int in_use;
+        int first_multi;
         uint8_t multi_overflow;
         uint8_t uni_overflow;
         uint8_t *macs;
@@ -100,6 +101,7 @@ static void virtio_net_reset(VirtIODevice *vdev)
     /* Flush any MAC and VLAN filter table state */
     n->mac_table.in_use = 0;
+    n->mac_table.first_multi = 0;
     n->mac_table.multi_overflow = 0;
     n->mac_table.uni_overflow = 0;
     memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
@@ -172,6 +174,7 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
         return VIRTIO_NET_ERR;
     n->mac_table.in_use = 0;
+    n->mac_table.first_multi = 0;
     n->mac_table.uni_overflow = 0;
     n->mac_table.multi_overflow = 0;
     memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
@@ -190,6 +193,8 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
         n->mac_table.uni_overflow = 1;
     }
+    n->mac_table.first_multi = n->mac_table.in_use;
+
     mac_data.entries = ldl_le_p(elem->out_sg[2].iov_base);
     if (sizeof(mac_data.entries) +
@@ -359,17 +364,24 @@ static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
         } else if (n->allmulti || n->mac_table.multi_overflow) {
             return 1;
         }
+
+        for (i = n->mac_table.first_multi; i < n->mac_table.in_use; i++) {
+            if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN)) {
+                return 1;
+            }
+        }
     } else { // unicast
         if (n->mac_table.uni_overflow) {
             return 1;
         } else 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;
+        for (i = 0; i < n->mac_table.first_multi; i++) {
+            if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN)) {
+                return 1;
+            }
+        }
     }
     return 0;
@@ -547,6 +559,7 @@ static void virtio_net_save(QEMUFile *f, void *opaque)
 static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIONet *n = opaque;
+    int i;
     if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
         return -EINVAL;
@@ -597,6 +610,14 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
         n->mac_table.uni_overflow = qemu_get_byte(f);
     }
+    /* Find the first multicast entry in the saved MAC filter */
+    for (i = 0; i < n->mac_table.in_use; i++) {
+        if (n->mac_table.macs[i * ETH_ALEN] & 1) {
+            break;
+        }
+    }
+    n->mac_table.first_multi = i;
+
     if (n->tx_timer_active) {
         qemu_mod_timer(n->tx_timer,
                        qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);