Copying in Stefan, Jason and Michael who know the virtio details
Dave
* Mikhail Sennikovsky (mikhail.sennikovs...@cloud.ionos.com) wrote:
> 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
>
> This patch fixes this by adding an extra argument to the set_features
> callback,
> specifying whether the offloads are to be reset, and setting it to false
> for the migration case.
>
> Signed-off-by: Mikhail Sennikovsky <mikhail.sennikovs...@cloud.ionos.com>
> ---
> hw/display/virtio-gpu-base.c | 3 ++-
> hw/net/virtio-net.c | 5 +++--
> hw/virtio/virtio.c | 10 +++++-----
> include/hw/virtio/virtio.h | 2 +-
> 4 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/hw/display/virtio-gpu-base.c b/hw/display/virtio-gpu-base.c
> index 55e0799..04d8a23 100644
> --- a/hw/display/virtio-gpu-base.c
> +++ b/hw/display/virtio-gpu-base.c
> @@ -193,7 +193,8 @@ virtio_gpu_base_get_features(VirtIODevice *vdev, uint64_t
> features,
> }
>
> static void
> -virtio_gpu_base_set_features(VirtIODevice *vdev, uint64_t features)
> +virtio_gpu_base_set_features(VirtIODevice *vdev, uint64_t features,
> + bool reset_offloads)
> {
> static const uint32_t virgl = (1 << VIRTIO_GPU_F_VIRGL);
> VirtIOGPUBase *g = VIRTIO_GPU_BASE(vdev);
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index b9e1cd7..5d108e5 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -743,7 +743,8 @@ static inline uint64_t
> virtio_net_supported_guest_offloads(VirtIONet *n)
> return virtio_net_guest_offloads_by_features(vdev->guest_features);
> }
>
> -static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
> +static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features,
> + bool reset_offloads)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
> int i;
> @@ -767,7 +768,7 @@ static void virtio_net_set_features(VirtIODevice *vdev,
> uint64_t features)
> n->rsc6_enabled = virtio_has_feature(features, VIRTIO_NET_F_RSC_EXT) &&
> virtio_has_feature(features, VIRTIO_NET_F_GUEST_TSO6);
>
> - if (n->has_vnet_hdr) {
> + if (reset_offloads && n->has_vnet_hdr) {
> n->curr_guest_offloads =
> virtio_net_guest_offloads_by_features(features);
> virtio_net_apply_guest_offloads(n);
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index a94ea18..b89f7b0 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2042,14 +2042,14 @@ const VMStateInfo virtio_vmstate_info = {
> .put = virtio_device_put,
> };
>
> -static int virtio_set_features_nocheck(VirtIODevice *vdev, uint64_t val)
> +static int virtio_set_features_nocheck(VirtIODevice *vdev, uint64_t val,
> bool reset_offloads)
> {
> VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> bool bad = (val & ~(vdev->host_features)) != 0;
>
> val &= vdev->host_features;
> if (k->set_features) {
> - k->set_features(vdev, val);
> + k->set_features(vdev, val, reset_offloads);
> }
> vdev->guest_features = val;
> return bad ? -1 : 0;
> @@ -2065,7 +2065,7 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t
> val)
> if (vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) {
> return -EINVAL;
> }
> - ret = virtio_set_features_nocheck(vdev, val);
> + ret = virtio_set_features_nocheck(vdev, val, true);
> if (!ret) {
> if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
> /* VIRTIO_RING_F_EVENT_IDX changes the size of the caches. */
> @@ -2217,14 +2217,14 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int
> version_id)
> * host_features.
> */
> uint64_t features64 = vdev->guest_features;
> - if (virtio_set_features_nocheck(vdev, features64) < 0) {
> + if (virtio_set_features_nocheck(vdev, features64, false) < 0) {
> error_report("Features 0x%" PRIx64 " unsupported. "
> "Allowed features: 0x%" PRIx64,
> features64, vdev->host_features);
> return -1;
> }
> } else {
> - if (virtio_set_features_nocheck(vdev, features) < 0) {
> + if (virtio_set_features_nocheck(vdev, features, false) < 0) {
> error_report("Features 0x%x unsupported. "
> "Allowed features: 0x%" PRIx64,
> features, vdev->host_features);
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index b189788..fd8cac5 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -128,7 +128,7 @@ typedef struct VirtioDeviceClass {
> uint64_t requested_features,
> Error **errp);
> uint64_t (*bad_features)(VirtIODevice *vdev);
> - void (*set_features)(VirtIODevice *vdev, uint64_t val);
> + void (*set_features)(VirtIODevice *vdev, uint64_t val, bool
> reset_offloads);
> int (*validate_features)(VirtIODevice *vdev);
> void (*get_config)(VirtIODevice *vdev, uint8_t *config);
> void (*set_config)(VirtIODevice *vdev, const uint8_t *config);
> --
> 2.7.4
>
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
