On Tue, May 9, 2023 at 11:44 PM Eugenio Pérez <epere...@redhat.com> wrote:
>
> Evaluating it at start time instead of initialization time may make the
> guest capable of dynamically adding or removing migration blockers.
>
> Also, moving to initialization reduces the number of ioctls in the
> migration, reducing failure possibilities.
>
> As a drawback we need to check for CVQ isolation twice: one time with no
> MQ negotiated and another one acking it, as long as the device supports
> it. This is because Vring ASID / group management is based on vq
> indexes, but we don't know the index of CVQ before negotiating MQ.
>
> Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> ---
> v2: Take out the reset of the device from vhost_vdpa_cvq_is_isolated
> v3: Only record cvq_isolated, true if the device have cvq isolated in
> both !MQ and MQ configurations.
> ---
> net/vhost-vdpa.c | 178 +++++++++++++++++++++++++++++++++++------------
> 1 file changed, 135 insertions(+), 43 deletions(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 3fb833fe76..29054b77a9 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -43,6 +43,10 @@ typedef struct VhostVDPAState {
>
> /* The device always have SVQ enabled */
> bool always_svq;
> +
> + /* The device can isolate CVQ in its own ASID */
> + bool cvq_isolated;
> +
> bool started;
> } VhostVDPAState;
>
> @@ -362,15 +366,8 @@ static NetClientInfo net_vhost_vdpa_info = {
> .check_peer_type = vhost_vdpa_check_peer_type,
> };
>
> -/**
> - * Get vring virtqueue group
> - *
> - * @device_fd vdpa device fd
> - * @vq_index Virtqueue index
> - *
> - * Return -errno in case of error, or vq group if success.
> - */
> -static int64_t vhost_vdpa_get_vring_group(int device_fd, unsigned vq_index)
> +static int64_t vhost_vdpa_get_vring_group(int device_fd, unsigned vq_index,
> + Error **errp)
> {
> struct vhost_vring_state state = {
> .index = vq_index,
> @@ -379,8 +376,7 @@ static int64_t vhost_vdpa_get_vring_group(int device_fd,
> unsigned vq_index)
>
> if (unlikely(r < 0)) {
> r = -errno;
> - error_report("Cannot get VQ %u group: %s", vq_index,
> - g_strerror(errno));
> + error_setg_errno(errp, errno, "Cannot get VQ %u group", vq_index);
> return r;
> }
>
> @@ -480,9 +476,9 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
> {
> VhostVDPAState *s, *s0;
> struct vhost_vdpa *v;
> - uint64_t backend_features;
> int64_t cvq_group;
> - int cvq_index, r;
> + int r;
> + Error *err = NULL;
>
> assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
>
> @@ -502,41 +498,22 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
> /*
> * If we early return in these cases SVQ will not be enabled. The
> migration
> * will be blocked as long as vhost-vdpa backends will not offer _F_LOG.
> - *
> - * Calling VHOST_GET_BACKEND_FEATURES as they are not available in v->dev
> - * yet.
> */
> - r = ioctl(v->device_fd, VHOST_GET_BACKEND_FEATURES, &backend_features);
> - if (unlikely(r < 0)) {
> - error_report("Cannot get vdpa backend_features: %s(%d)",
> - g_strerror(errno), errno);
> - return -1;
> + if (!vhost_vdpa_net_valid_svq_features(v->dev->features, NULL)) {
> + return 0;
> }
> - if (!(backend_features & BIT_ULL(VHOST_BACKEND_F_IOTLB_ASID)) ||
> - !vhost_vdpa_net_valid_svq_features(v->dev->features, NULL)) {
> +
> + if (!s->cvq_isolated) {
> return 0;
> }
>
> - /*
> - * Check if all the virtqueues of the virtio device are in a different vq
> - * than the last vq. VQ group of last group passed in cvq_group.
> - */
> - cvq_index = v->dev->vq_index_end - 1;
> - cvq_group = vhost_vdpa_get_vring_group(v->device_fd, cvq_index);
> + cvq_group = vhost_vdpa_get_vring_group(v->device_fd,
> + v->dev->vq_index_end - 1,
> + &err);
> if (unlikely(cvq_group < 0)) {
> + error_report_err(err);
> return cvq_group;
> }
> - for (int i = 0; i < cvq_index; ++i) {
> - int64_t group = vhost_vdpa_get_vring_group(v->device_fd, i);
> -
> - if (unlikely(group < 0)) {
> - return group;
> - }
> -
> - if (group == cvq_group) {
> - return 0;
> - }
> - }
>
> r = vhost_vdpa_set_address_space_id(v, cvq_group,
> VHOST_VDPA_NET_CVQ_ASID);
> if (unlikely(r < 0)) {
> @@ -799,6 +776,111 @@ static const VhostShadowVirtqueueOps
> vhost_vdpa_net_svq_ops = {
> .avail_handler = vhost_vdpa_net_handle_ctrl_avail,
> };
>
> +/**
> + * Probe the device to check control virtqueue is isolated.
> + *
> + * @device_fd vhost-vdpa file descriptor
> + * @features features to negotiate
> + * @cvq_index Control vq index
> + *
> + * Returns -1 in case of error, 0 if false and 1 if true
> + */
> +static int vhost_vdpa_cvq_is_isolated(int device_fd, uint64_t features,
> + unsigned cvq_index, Error **errp)
> +{
> + int64_t cvq_group;
> + int r;
> +
> + r = vhost_vdpa_set_dev_features_fd(device_fd, features);
> + if (unlikely(r < 0)) {
> + error_setg_errno(errp, -r, "Cannot set device features");
> + return r;
> + }
> +
> + cvq_group = vhost_vdpa_get_vring_group(device_fd, cvq_index, errp);
> + if (unlikely(cvq_group < 0)) {
> + return cvq_group;
> + }
> +
> + for (int i = 0; i < cvq_index; ++i) {
> + int64_t group = vhost_vdpa_get_vring_group(device_fd, i, errp);
> +
> + if (unlikely(group < 0)) {
> + return group;
> + }
> +
> + if (group == (int64_t)cvq_group) {
> + return 0;
> + }
> + }
> +
> + return 1;
> +}
> +
> +/**
> + * Probe if CVQ is isolated when the device is MQ and when it is not MQ
> + *
> + * @device_fd The vdpa device fd
> + * @features Features offered by the device.
> + * @cvq_index The control vq index if mq is negotiated. Ignored
> + * otherwise.
> + *
> + * Returns <0 in case of failure, 0 if false and 1 if true.
> + */
> +static int vhost_vdpa_probe_cvq_isolation(int device_fd, uint64_t features,
> + int cvq_index, Error **errp)
> +{
> + uint64_t backend_features;
> + int r;
> +
> + ERRP_GUARD();
> +
> + r = ioctl(device_fd, VHOST_GET_BACKEND_FEATURES, &backend_features);
> + if (unlikely(r < 0)) {
> + error_setg_errno(errp, errno, "Cannot get vdpa backend_features");
> + return r;
> + }
> +
> + if (!(backend_features & BIT_ULL(VHOST_BACKEND_F_IOTLB_ASID))) {
> + return 0;
> + }
> +
> + r = vhost_vdpa_cvq_is_isolated(device_fd,
> + features & ~BIT_ULL(VIRTIO_NET_F_MQ), 2,
> + errp);
> + if (unlikely(r < 0)) {
> + if (r != -ENOTSUP) {
> + return r;
> + }
> +
> + /*
> + * The kernel report VHOST_BACKEND_F_IOTLB_ASID if the vdpa frontend
> + * support ASID even if the parent driver does not. The CVQ cannot
> be
> + * isolated in this case.
> + */
> + error_free(*errp);
> + *errp = NULL;
> + return 0;
> + }
> +
> + if (r == 0) {
> + return 0;
> + }
> +
> + vhost_vdpa_reset_status_fd(device_fd);
> + if (!(features & BIT_ULL(VIRTIO_NET_F_MQ))) {
> + return 0;
> + }
> +
> + r = vhost_vdpa_cvq_is_isolated(device_fd, features, cvq_index * 2, errp);
I think checking this once should be sufficient. That is to say, it
should be a bug if there's hardware that puts cvq in a dedicated group
in MQ but not in SQ.
Thanks
> + if (unlikely(r < 0)) {
> + return r;
> + }
> +
> + vhost_vdpa_reset_status_fd(device_fd);
> + return r;
> +}
> +
> static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
> const char *device,
> const char *name,
> @@ -808,16 +890,25 @@ static NetClientState
> *net_vhost_vdpa_init(NetClientState *peer,
> bool is_datapath,
> bool svq,
> struct vhost_vdpa_iova_range
> iova_range,
> - uint64_t features)
> + uint64_t features,
> + Error **errp)
> {
> NetClientState *nc = NULL;
> VhostVDPAState *s;
> int ret = 0;
> assert(name);
> + int cvq_isolated;
> +
> if (is_datapath) {
> nc = qemu_new_net_client(&net_vhost_vdpa_info, peer, device,
> name);
> } else {
> + cvq_isolated = vhost_vdpa_probe_cvq_isolation(vdpa_device_fd,
> features,
> + queue_pair_index,
> errp);
> + if (unlikely(cvq_isolated < 0)) {
> + return NULL;
> + }
> +
> nc = qemu_new_net_control_client(&net_vhost_vdpa_cvq_info, peer,
> device, name);
> }
> @@ -844,6 +935,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState
> *peer,
>
> s->vhost_vdpa.shadow_vq_ops = &vhost_vdpa_net_svq_ops;
> s->vhost_vdpa.shadow_vq_ops_opaque = s;
> + s->cvq_isolated = cvq_isolated;
>
> /*
> * TODO: We cannot migrate devices with CVQ as there is no way to set
> @@ -972,7 +1064,7 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char
> *name,
> for (i = 0; i < queue_pairs; i++) {
> ncs[i] = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
> vdpa_device_fd, i, 2, true, opts->x_svq,
> - iova_range, features);
> + iova_range, features, errp);
> if (!ncs[i])
> goto err;
> }
> @@ -980,7 +1072,7 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char
> *name,
> if (has_cvq) {
> nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
> vdpa_device_fd, i, 1, false,
> - opts->x_svq, iova_range, features);
> + opts->x_svq, iova_range, features, errp);
> if (!nc)
> goto err;
> }
> --
> 2.31.1
>
