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virtio-net: prevent offloads reset on migration

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Currently offloads disabled by guest via the VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET
command are not preserved on VM migration.
Instead all offloads reported by guest features (via VIRTIO_PCI_GUEST_FEATURES)
get enabled.
What happens is: first the VirtIONet::curr_guest_offloads gets restored and offloads
are getting set correctly:

 #0  qemu_set_offload (nc=0x555556a11400, csum=1, tso4=0, tso6=0, ecn=0, ufo=0) at net/net.c:474
 #1  virtio_net_apply_guest_offloads (n=0x555557701ca0) at hw/net/virtio-net.c:720
 #2  virtio_net_post_load_device (opaque=0x555557701ca0, version_id=11) at hw/net/virtio-net.c:2334
 #3  vmstate_load_state (f=0x5555569dc010, vmsd=0x555556577c80 <vmstate_virtio_net_device>, opaque=0x555557701ca0, version_id=11)
     at migration/vmstate.c:168
 #4  virtio_load (vdev=0x555557701ca0, f=0x5555569dc010, version_id=11) at hw/virtio/virtio.c:2197
 #5  virtio_device_get (f=0x5555569dc010, opaque=0x555557701ca0, size=0, field=0x55555668cd00 <__compound_literal.5>) at hw/virtio/virtio.c:2036
 #6  vmstate_load_state (f=0x5555569dc010, vmsd=0x555556577ce0 <vmstate_virtio_net>, opaque=0x555557701ca0, version_id=11) at migration/vmstate.c:143
 #7  vmstate_load (f=0x5555569dc010, se=0x5555578189e0) at migration/savevm.c:829
 #8  qemu_loadvm_section_start_full (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2211
 #9  qemu_loadvm_state_main (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2395
 #10 qemu_loadvm_state (f=0x5555569dc010) at migration/savevm.c:2467
 #11 process_incoming_migration_co (opaque=0x0) at migration/migration.c:449

However later on the features are getting restored, and offloads get reset to
everything supported by features:

 #0  qemu_set_offload (nc=0x555556a11400, csum=1, tso4=1, tso6=1, ecn=0, ufo=0) at net/net.c:474
 #1  virtio_net_apply_guest_offloads (n=0x555557701ca0) at hw/net/virtio-net.c:720
 #2  virtio_net_set_features (vdev=0x555557701ca0, features=5104441767) at hw/net/virtio-net.c:773
 #3  virtio_set_features_nocheck (vdev=0x555557701ca0, val=5104441767) at hw/virtio/virtio.c:2052
 #4  virtio_load (vdev=0x555557701ca0, f=0x5555569dc010, version_id=11) at hw/virtio/virtio.c:2220
 #5  virtio_device_get (f=0x5555569dc010, opaque=0x555557701ca0, size=0, field=0x55555668cd00 <__compound_literal.5>) at hw/virtio/virtio.c:2036
 #6  vmstate_load_state (f=0x5555569dc010, vmsd=0x555556577ce0 <vmstate_virtio_net>, opaque=0x555557701ca0, version_id=11) at migration/vmstate.c:143
 #7  vmstate_load (f=0x5555569dc010, se=0x5555578189e0) at migration/savevm.c:829
 #8  qemu_loadvm_section_start_full (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2211
 #9  qemu_loadvm_state_main (f=0x5555569dc010, mis=0x5555569eee20) at migration/savevm.c:2395
 #10 qemu_loadvm_state (f=0x5555569dc010) at migration/savevm.c:2467
 #11 process_incoming_migration_co (opaque=0x0) at migration/migration.c:449

Fix this by preserving the state in saved_guest_offloads field and
pushing out offload initialization to the new post load hook.

Cc: qemu-stable@nongnu.org
Signed-off-by: Mikhail Sennikovsky <mikhail.sennikovskii@cloud.ionos.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Mikhail Sennikovsky 2019-10-11 15:58:04 +02:00 committed by Jason Wang
parent 1dd713837c
commit 7788c3f2e2
2 changed files with 26 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
hw/net/virtio-net.c
View File

@ -2333,9 +2333,13 @@ static int virtio_net_post_load_device(void *opaque, int version_id)
n->curr_guest_offloads = virtio_net_supported_guest_offloads(n);
}
if (peer_has_vnet_hdr(n)) {
virtio_net_apply_guest_offloads(n);
}
/*
* curr_guest_offloads will be later overwritten by the
* virtio_set_features_nocheck call done from the virtio_load.
* Here we make sure it is preserved and restored accordingly
* in the virtio_net_post_load_virtio callback.
*/
n->saved_guest_offloads = n->curr_guest_offloads;
virtio_net_set_queues(n);
@ -2370,6 +2374,22 @@ static int virtio_net_post_load_device(void *opaque, int version_id)
return 0;
}
static int virtio_net_post_load_virtio(VirtIODevice *vdev)
{
VirtIONet *n = VIRTIO_NET(vdev);
/*
* The actual needed state is now in saved_guest_offloads,
* see virtio_net_post_load_device for detail.
* Restore it back and apply the desired offloads.
*/
n->curr_guest_offloads = n->saved_guest_offloads;
if (peer_has_vnet_hdr(n)) {
virtio_net_apply_guest_offloads(n);
}
return 0;
}
/* tx_waiting field of a VirtIONetQueue */
static const VMStateDescription vmstate_virtio_net_queue_tx_waiting = {
.name = "virtio-net-queue-tx_waiting",
@ -2912,6 +2932,7 @@ static void virtio_net_class_init(ObjectClass *klass, void *data)
vdc->guest_notifier_mask = virtio_net_guest_notifier_mask;
vdc->guest_notifier_pending = virtio_net_guest_notifier_pending;
vdc->legacy_features |= (0x1 << VIRTIO_NET_F_GSO);
vdc->post_load = virtio_net_post_load_virtio;
vdc->vmsd = &vmstate_virtio_net_device;
}

2
include/hw/virtio/virtio-net.h
View File

@ -182,6 +182,8 @@ struct VirtIONet {
char *netclient_name;
char *netclient_type;
uint64_t curr_guest_offloads;
/* used on saved state restore phase to preserve the curr_guest_offloads */
uint64_t saved_guest_offloads;
AnnounceTimer announce_timer;
bool needs_vnet_hdr_swap;
bool mtu_bypass_backend;