[Qemu-devel] [PATCH 2/2 V3] virtio-net: dynamic network offloads configuration

[Dmitry Fleytman <dmitry@daynix.com>]

From: Dmitry Fleytman <dfleytma@redhat.com>

Virtio-net driver currently negotiates network offloads
on startup via features mechanism and have no ability to
change offloads state later.
This patch introduced a new control command that allows
to configure device network offloads state dynamically.
The patch also introduces a new feature flag
VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.

Signed-off-by: Dmitry Fleytman <dfleytma@redhat.com>
---
 hw/pc.h         |   4 ++
 hw/virtio-net.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++++--------
 hw/virtio-net.h |  19 ++++++++++
 3 files changed, 119 insertions(+), 15 deletions(-)

diff --git a/hw/pc.h b/hw/pc.h
index 8e1dd4c..7ca4698 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -221,6 +221,10 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
             .property = "vectors",\
             /* DEV_NVECTORS_UNSPECIFIED as a uint32_t string */\
             .value    = stringify(0xFFFFFFFF),\
+        },{ \
+            .driver   = "virtio-net-pci", \
+            .property = "ctrl_guest_offloads", \
+            .value    = "off", \
         },{\
             .driver   = "e1000",\
             .property = "romfile",\
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 5917740..d040f96 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -360,6 +360,48 @@ static uint32_t virtio_net_bad_features(VirtIODevice *vdev)
     return features;
 }
 
+static void virtio_net_apply_offloads(VirtIONet *n)
+{
+    tap_set_offload(qemu_get_subqueue(n->nic, 0)->peer,
+                    !!(n->curr_offloads & VIRTIO_NET_OFFLOAD_GUEST_CSUM),
+                    !!(n->curr_offloads & VIRTIO_NET_OFFLOAD_GUEST_TSO4),
+                    !!(n->curr_offloads & VIRTIO_NET_OFFLOAD_GUEST_TSO6),
+                    !!(n->curr_offloads & VIRTIO_NET_OFFLOAD_GUEST_ECN),
+                    !!(n->curr_offloads & VIRTIO_NET_OFFLOAD_GUEST_UFO));
+}
+
+static uint32_t virtio_net_offloads_by_features(uint32_t features)
+{
+    uint32_t offloads = 0;
+
+    if ((1 << VIRTIO_NET_F_GUEST_CSUM) & features) {
+        offloads |= VIRTIO_NET_OFFLOAD_GUEST_CSUM;
+    }
+
+    if ((1 << VIRTIO_NET_F_GUEST_TSO4) & features) {
+        offloads |= VIRTIO_NET_OFFLOAD_GUEST_TSO4;
+    }
+
+    if ((1 << VIRTIO_NET_F_GUEST_TSO6) & features) {
+        offloads |= VIRTIO_NET_OFFLOAD_GUEST_TSO6;
+    }
+
+    if ((1 << VIRTIO_NET_F_GUEST_ECN) & features) {
+        offloads |= VIRTIO_NET_OFFLOAD_GUEST_ECN;
+    }
+
+    if ((1 << VIRTIO_NET_F_GUEST_UFO) & features) {
+        offloads |= VIRTIO_NET_OFFLOAD_GUEST_UFO;
+    }
+
+    return offloads;
+}
+
+static inline uint32_t virtio_net_supported_offloads(VirtIONet *n)
+{
+    return virtio_net_offloads_by_features(n->vdev.guest_features);
+}
+
 static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
 {
     VirtIONet *n = to_virtio_net(vdev);
@@ -371,12 +413,8 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
     virtio_net_set_mrg_rx_bufs(n, !!(features & (1 << VIRTIO_NET_F_MRG_RXBUF)));
 
     if (n->has_vnet_hdr) {
-        tap_set_offload(qemu_get_subqueue(n->nic, 0)->peer,
-                        (features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
-                        (features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
-                        (features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
-                        (features >> VIRTIO_NET_F_GUEST_ECN)  & 1,
-                        (features >> VIRTIO_NET_F_GUEST_UFO)  & 1);
+        n->curr_offloads = virtio_net_offloads_by_features(features);
+        virtio_net_apply_offloads(n);
     }
 
     for (i = 0;  i < n->max_queues; i++) {
@@ -422,6 +460,42 @@ static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
     return VIRTIO_NET_OK;
 }
 
+static int virtio_net_handle_offloads(VirtIONet *n, uint8_t cmd,
+                                     struct iovec *iov, unsigned int iov_cnt)
+{
+    uint32_t offloads;
+    size_t s;
+
+    if (!((1 << VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) & n->vdev.guest_features)) {
+        return VIRTIO_NET_ERR;
+    }
+
+    s = iov_to_buf(iov, iov_cnt, 0, &offloads, sizeof(offloads));
+    if (s != sizeof(offloads)) {
+        return VIRTIO_NET_ERR;
+    }
+
+    if (cmd == VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET) {
+        uint32_t supported_offloads;
+
+        if (!n->has_vnet_hdr) {
+            return VIRTIO_NET_ERR;
+        }
+
+        supported_offloads = virtio_net_supported_offloads(n);
+        if (offloads & ~supported_offloads) {
+            return VIRTIO_NET_ERR;
+        }
+
+        n->curr_offloads = offloads;
+        virtio_net_apply_offloads(n);
+
+        return VIRTIO_NET_OK;
+    } else {
+        return VIRTIO_NET_ERR;
+    }
+}
+
 static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
                                  struct iovec *iov, unsigned int iov_cnt)
 {
@@ -591,6 +665,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
             status = virtio_net_handle_vlan_table(n, ctrl.cmd, iov, iov_cnt);
         } else if (ctrl.class == VIRTIO_NET_CTRL_MQ) {
             status = virtio_net_handle_mq(n, ctrl.cmd, iov, iov_cnt);
+        } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) {
+            status = virtio_net_handle_offloads(n, ctrl.cmd, iov, iov_cnt);
         }
 
         s = iov_from_buf(elem.in_sg, elem.in_num, 0, &status, sizeof(status));
@@ -1100,6 +1176,10 @@ static void virtio_net_save(QEMUFile *f, void *opaque)
             qemu_put_be32(f, n->vqs[i].tx_waiting);
         }
     }
+
+    if ((1 << VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) & n->vdev.guest_features) {
+        qemu_put_be32(f, n->curr_offloads);
+    }
 }
 
 static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
@@ -1156,15 +1236,6 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
             error_report("virtio-net: saved image requires vnet_hdr=on");
             return -1;
         }
-
-        if (n->has_vnet_hdr) {
-            tap_set_offload(qemu_get_queue(n->nic)->peer,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_ECN)  & 1,
-                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_UFO)  & 1);
-        }
     }
 
     if (version_id >= 9) {
@@ -1198,6 +1269,16 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
         }
     }
 
+    if ((1 << VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) & n->vdev.guest_features) {
+        n->curr_offloads = qemu_get_be32(f);
+    } else {
+        n->curr_offloads = virtio_net_supported_offloads(n);
+    }
+
+    if (peer_has_vnet_hdr(n)) {
+        virtio_net_apply_offloads(n);
+    }
+
     virtio_net_set_queues(n);
 
     /* Find the first multicast entry in the saved MAC filter */
diff --git a/hw/virtio-net.h b/hw/virtio-net.h
index 4d1a8cd..7e93368 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -27,6 +27,8 @@
 /* The feature bitmap for virtio net */
 #define VIRTIO_NET_F_CSUM       0       /* Host handles pkts w/ partial csum */
 #define VIRTIO_NET_F_GUEST_CSUM 1       /* Guest handles pkts w/ partial csum */
+#define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Control channel offload
+                                         * configuration support */
 #define VIRTIO_NET_F_MAC        5       /* Host has given MAC address. */
 #define VIRTIO_NET_F_GSO        6       /* Host handles pkts w/ any GSO type */
 #define VIRTIO_NET_F_GUEST_TSO4 7       /* Guest can handle TSOv4 in. */
@@ -182,6 +184,7 @@ typedef struct VirtIONet {
     uint16_t max_queues;
     uint16_t curr_queues;
     size_t config_size;
+    uint32_t curr_offloads;
 } VirtIONet;
 
 #define VIRTIO_NET_CTRL_MAC    1
@@ -221,6 +224,21 @@ struct virtio_net_ctrl_mq {
  #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN        1
  #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX        0x8000
 
+/*
+ * Control network offloads
+ *
+ * Dynamic offloads are available with the
+ * VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature bit.
+ */
+#define VIRTIO_NET_CTRL_GUEST_OFFLOADS   5
+ #define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET        0
+
+#define VIRTIO_NET_OFFLOAD_GUEST_CSUM       1
+#define VIRTIO_NET_OFFLOAD_GUEST_TSO4       2
+#define VIRTIO_NET_OFFLOAD_GUEST_TSO6       4
+#define VIRTIO_NET_OFFLOAD_GUEST_ECN        8
+#define VIRTIO_NET_OFFLOAD_GUEST_UFO       16
+
 #define DEFINE_VIRTIO_NET_FEATURES(_state, _field) \
         DEFINE_VIRTIO_COMMON_FEATURES(_state, _field), \
         DEFINE_PROP_BIT("csum", _state, _field, VIRTIO_NET_F_CSUM, true), \
@@ -241,6 +259,7 @@ struct virtio_net_ctrl_mq {
         DEFINE_PROP_BIT("ctrl_vlan", _state, _field, VIRTIO_NET_F_CTRL_VLAN, true), \
         DEFINE_PROP_BIT("ctrl_rx_extra", _state, _field, VIRTIO_NET_F_CTRL_RX_EXTRA, true), \
         DEFINE_PROP_BIT("ctrl_mac_addr", _state, _field, VIRTIO_NET_F_CTRL_MAC_ADDR, true), \
+        DEFINE_PROP_BIT("ctrl_guest_offloads", _state, _field, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, true), \
         DEFINE_PROP_BIT("mq", _state, _field, VIRTIO_NET_F_MQ, false)
 
 #endif
-- 
1.8.1.4