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virtio-net: dynamic network offloads configuration
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Virtio-net driver currently negotiates network offloads
on startup via features mechanism and have no ability to
disable and re-enable offloads 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>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20130520081814.GA8162@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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Dmitry Fleytman authored and Anthony Liguori committed May 22, 2013
1 parent 2b22002 commit 644c985
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Showing 3 changed files with 101 additions and 15 deletions.
99 changes: 84 additions & 15 deletions hw/net/virtio-net.c
View file
Expand Up @@ -359,6 +359,34 @@ static uint32_t virtio_net_bad_features(VirtIODevice *vdev)
return features;
}

static void virtio_net_apply_guest_offloads(VirtIONet *n)
{
tap_set_offload(qemu_get_subqueue(n->nic, 0)->peer,
!!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_CSUM)),
!!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_TSO4)),
!!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_TSO6)),
!!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_ECN)),
!!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_UFO)));
}

static uint64_t virtio_net_guest_offloads_by_features(uint32_t features)
{
static const uint64_t guest_offloads_mask =
(1ULL << VIRTIO_NET_F_GUEST_CSUM) |
(1ULL << VIRTIO_NET_F_GUEST_TSO4) |
(1ULL << VIRTIO_NET_F_GUEST_TSO6) |
(1ULL << VIRTIO_NET_F_GUEST_ECN) |
(1ULL << VIRTIO_NET_F_GUEST_UFO);

return guest_offloads_mask & features;
}

static inline uint64_t virtio_net_supported_guest_offloads(VirtIONet *n)
{
VirtIODevice *vdev = VIRTIO_DEVICE(n);
return virtio_net_guest_offloads_by_features(vdev->guest_features);
}

static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
{
VirtIONet *n = VIRTIO_NET(vdev);
Expand All @@ -369,12 +397,9 @@ 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_guest_offloads =
virtio_net_guest_offloads_by_features(features);
virtio_net_apply_guest_offloads(n);
}

for (i = 0; i < n->max_queues; i++) {
Expand Down Expand Up @@ -420,6 +445,43 @@ 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)
{
VirtIODevice *vdev = VIRTIO_DEVICE(n);
uint64_t offloads;
size_t s;

if (!((1 << VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) & 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) {
uint64_t supported_offloads;

if (!n->has_vnet_hdr) {
return VIRTIO_NET_ERR;
}

supported_offloads = virtio_net_supported_guest_offloads(n);
if (offloads & ~supported_offloads) {
return VIRTIO_NET_ERR;
}

n->curr_guest_offloads = offloads;
virtio_net_apply_guest_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)
{
Expand Down Expand Up @@ -590,6 +652,8 @@ 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));
Expand Down Expand Up @@ -1110,6 +1174,10 @@ 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) & vdev->guest_features) {
qemu_put_be64(f, n->curr_guest_offloads);
}
}

static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
Expand Down Expand Up @@ -1167,15 +1235,6 @@ 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,
(vdev->guest_features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
(vdev->guest_features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
(vdev->guest_features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
(vdev->guest_features >> VIRTIO_NET_F_GUEST_ECN) & 1,
(vdev->guest_features >> VIRTIO_NET_F_GUEST_UFO) & 1);
}
}

if (version_id >= 9) {
Expand Down Expand Up @@ -1209,6 +1268,16 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
}
}

if ((1 << VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) & vdev->guest_features) {
n->curr_guest_offloads = qemu_get_be64(f);
} else {
n->curr_guest_offloads = virtio_net_supported_guest_offloads(n);
}

if (peer_has_vnet_hdr(n)) {
virtio_net_apply_guest_offloads(n);
}

virtio_net_set_queues(n);

/* Find the first multicast entry in the saved MAC filter */
Expand Down
4 changes: 4 additions & 0 deletions include/hw/i386/pc.h
View file
Expand Up @@ -217,6 +217,10 @@ 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",\
Expand Down
13 changes: 13 additions & 0 deletions include/hw/virtio/virtio-net.h
View file
Expand Up @@ -31,6 +31,8 @@
/* 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. */
Expand Down Expand Up @@ -190,6 +192,7 @@ typedef struct VirtIONet {
size_t config_size;
char *netclient_name;
char *netclient_type;
uint64_t curr_guest_offloads;
} VirtIONet;

#define VIRTIO_NET_CTRL_MAC 1
Expand Down Expand Up @@ -229,6 +232,15 @@ 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 DEFINE_VIRTIO_NET_FEATURES(_state, _field) \
DEFINE_VIRTIO_COMMON_FEATURES(_state, _field), \
DEFINE_PROP_BIT("csum", _state, _field, VIRTIO_NET_F_CSUM, true), \
Expand All @@ -249,6 +261,7 @@ 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)

#define DEFINE_VIRTIO_NET_PROPERTIES(_state, _field) \
Expand Down

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