[PATCH RFC v2 3/4] vdpa: Restore packet receive filtering state relative with _F_CTRL_RX feature

[Hawkins Jiawei]

This patch introduces vhost_vdpa_net_load_rx_mode()
and vhost_vdpa_net_load_rx() to restore the packet
receive filtering state in relation to
VIRTIO_NET_F_CTRL_RX feature at device's startup.

Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
---
v2:
  - avoid sending CVQ command in default state suggested by Eugenio

v1: 
86eeddcd6f6b04e5c1e44e901ddea3b1b8b6c183.1687402580.git.yin31149@gmail.com/">https://lore.kernel.org/all/86eeddcd6f6b04e5c1e44e901ddea3b1b8b6c183.1687402580.git.yin31149@gmail.com/

 net/vhost-vdpa.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index cb45c84c88..9d5d88756c 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -792,6 +792,106 @@ static int vhost_vdpa_net_load_offloads(VhostVDPAState *s,
     return 0;
 }
 
+static int vhost_vdpa_net_load_rx_mode(VhostVDPAState *s,
+                                       uint8_t cmd,
+                                       uint8_t on)
+{
+    ssize_t dev_written;
+    const struct iovec data = {
+        .iov_base = &on,
+        .iov_len = sizeof(on),
+    };
+    dev_written = vhost_vdpa_net_load_cmd(s, VIRTIO_NET_CTRL_RX,
+                                          cmd, &data, 1);
+    if (unlikely(dev_written < 0)) {
+        return dev_written;
+    }
+    if (*s->status != VIRTIO_NET_OK) {
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static int vhost_vdpa_net_load_rx(VhostVDPAState *s,
+                                  const VirtIONet *n)
+{
+    uint8_t on;
+    int r;
+
+    if (virtio_vdev_has_feature(&n->parent_obj, VIRTIO_NET_F_CTRL_RX)) {
+        /* Load the promiscous mode */
+        if (n->mac_table.uni_overflow) {
+            /*
+             * According to VirtIO standard, "Since there are no guarantees,
+             * it can use a hash filter or silently switch to
+             * allmulti or promiscuous mode if it is given too many addresses."
+             *
+             * QEMU ignores non-multicast(unicast) MAC addresses and
+             * marks `uni_overflow` for the device internal state
+             * if guest sets too many non-multicast(unicast) MAC addresses.
+             * Therefore, we should turn promiscous mode on in this case.
+             */
+            on = 1;
+        } else {
+            on = n->promisc;
+        }
+        if (on != 1) {
+            /*
+             * According to virtio_net_reset(), device turns promiscuous mode 
on
+             * by default.
+             *
+             * Therefore, there is no need to send this CVQ command if the
+             * driver also sets promiscuous mode on, which aligns with
+             * the device's defaults.
+             *
+             * Note that the device's defaults can mismatch the driver's
+             * configuration only at live migration.
+             */
+            r = vhost_vdpa_net_load_rx_mode(s, VIRTIO_NET_CTRL_RX_PROMISC, on);
+            if (r < 0) {
+                return r;
+            }
+        }
+
+        /* Load the all-multicast mode */
+        if (n->mac_table.multi_overflow) {
+            /*
+             * According to VirtIO standard, "Since there are no guarantees,
+             * it can use a hash filter or silently switch to
+             * allmulti or promiscuous mode if it is given too many addresses."
+             *
+             * QEMU ignores multicast MAC addresses and
+             * marks `multi_overflow` for the device internal state
+             * if guest sets too many multicast MAC addresses.
+             * Therefore, we should turn all-multicast mode on in this case.
+             */
+            on = 1;
+        } else {
+            on = n->allmulti;
+        }
+        if (on != 0) {
+            /*
+             * According to virtio_net_reset(), device turns all-multicast mode
+             * off by default.
+             *
+             * Therefore, there is no need to send this CVQ command if the
+             * driver also sets all-multicast mode off, which aligns with
+             * the device's defaults.
+             *
+             * Note that the device's defaults can mismatch the driver's
+             * configuration only at live migration.
+             */
+            r = vhost_vdpa_net_load_rx_mode(s, VIRTIO_NET_CTRL_RX_ALLMULTI, 
on);
+            if (r < 0) {
+                return r;
+            }
+        }
+    }
+
+    return 0;
+}
+
 static int vhost_vdpa_net_load(NetClientState *nc)
 {
     VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
@@ -818,6 +918,10 @@ static int vhost_vdpa_net_load(NetClientState *nc)
     if (unlikely(r)) {
         return r;
     }
+    r = vhost_vdpa_net_load_rx(s, n);
+    if (unlikely(r)) {
+        return r;
+    }
 
     return 0;
 }
-- 
2.25.1