On Fri, 2023-12-15 at 18:56 +0100, Eugenio Perez Martin wrote: > On Fri, Dec 15, 2023 at 3:13 PM Dragos Tatulea <dtatulea@xxxxxxxxxx> wrote: > > > > On Fri, 2023-12-15 at 12:35 +0000, Dragos Tatulea wrote: > > > On Thu, 2023-12-14 at 19:30 +0100, Eugenio Perez Martin wrote: > > > > On Thu, Dec 14, 2023 at 4:51 PM Dragos Tatulea <dtatulea@xxxxxxxxxx> wrote: > > > > > > > > > > On Thu, 2023-12-14 at 08:45 -0500, Michael S. Tsirkin wrote: > > > > > > On Thu, Dec 14, 2023 at 01:39:55PM +0000, Dragos Tatulea wrote: > > > > > > > On Tue, 2023-12-12 at 15:44 -0800, Si-Wei Liu wrote: > > > > > > > > > > > > > > > > On 12/12/2023 11:21 AM, Eugenio Perez Martin wrote: > > > > > > > > > On Tue, Dec 5, 2023 at 11:46 AM Dragos Tatulea <dtatulea@xxxxxxxxxx> wrote: > > > > > > > > > > Addresses get set by .set_vq_address. hw vq addresses will be updated on > > > > > > > > > > next modify_virtqueue. > > > > > > > > > > > > > > > > > > > > Signed-off-by: Dragos Tatulea <dtatulea@xxxxxxxxxx> > > > > > > > > > > Reviewed-by: Gal Pressman <gal@xxxxxxxxxx> > > > > > > > > > > Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx> > > > > > > > > > I'm kind of ok with this patch and the next one about state, but I > > > > > > > > > didn't ack them in the previous series. > > > > > > > > > > > > > > > > > > My main concern is that it is not valid to change the vq address after > > > > > > > > > DRIVER_OK in VirtIO, which vDPA follows. Only memory maps are ok to > > > > > > > > > change at this moment. I'm not sure about vq state in vDPA, but vhost > > > > > > > > > forbids changing it with an active backend. > > > > > > > > > > > > > > > > > > Suspend is not defined in VirtIO at this moment though, so maybe it is > > > > > > > > > ok to decide that all of these parameters may change during suspend. > > > > > > > > > Maybe the best thing is to protect this with a vDPA feature flag. > > > > > > > > I think protect with vDPA feature flag could work, while on the other > > > > > > > > hand vDPA means vendor specific optimization is possible around suspend > > > > > > > > and resume (in case it helps performance), which doesn't have to be > > > > > > > > backed by virtio spec. Same applies to vhost user backend features, > > > > > > > > variations there were not backed by spec either. Of course, we should > > > > > > > > try best to make the default behavior backward compatible with > > > > > > > > virtio-based backend, but that circles back to no suspend definition in > > > > > > > > the current virtio spec, for which I hope we don't cease development on > > > > > > > > vDPA indefinitely. After all, the virtio based vdap backend can well > > > > > > > > define its own feature flag to describe (minor difference in) the > > > > > > > > suspend behavior based on the later spec once it is formed in future. > > > > > > > > > > > > > > > So what is the way forward here? From what I understand the options are: > > > > > > > > > > > > > > 1) Add a vdpa feature flag for changing device properties while suspended. > > > > > > > > > > > > > > 2) Drop these 2 patches from the series for now. Not sure if this makes sense as > > > > > > > this. But then Si-Wei's qemu device suspend/resume poc [0] that exercises this > > > > > > > code won't work anymore. This means the series would be less well tested. > > > > > > > > > > > > > > Are there other possible options? What do you think? > > > > > > > > > > > > > > [0] https://github.com/siwliu-kernel/qemu/tree/svq-resume-wip > > > > > > > > > > > > I am fine with either of these. > > > > > > > > > > > How about allowing the change only under the following conditions: > > > > > vhost_vdpa_can_suspend && vhost_vdpa_can_resume && > > > > > VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK is set > > > > > > > > > > ? > > > > > > > > I think the best option by far is 1, as there is no hint in the > > > > combination of these 3 indicating that you can change device > > > > properties in the suspended state. > > > > > > > Sure. Will respin a v3 without these two patches. > > > > > > Another series can implement option 2 and add these 2 patches on top. > > Hmm...I misunderstood your statement and sent a erroneus v3. You said that > > having a feature flag is the best option. > > > > Will add a feature flag in v4: is this similar to the > > VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK flag? > > > > Right, it should be easy to return it from .get_backend_features op if > the FW returns that capability, isn't it? > Yes, that's easy. But I wonder if we need one feature bit for each type of change: - VHOST_BACKEND_F_CHANGEABLE_VQ_ADDR_IN_SUSPEND - VHOST_BACKEND_F_CHANGEABLE_VQ_STATE_IN_SUSPEND Or would a big one VHOST_BACKEND_F_CAN_RECONFIG_VQ_IN_SUSPEND suffice? To me having individual feature bits makes sense. But it could also takes too many bits if more changes are required. Thanks, Dragos > > Thanks, > > Dragos > > > > > > > Thanks, > > > > > Dragos > > > > > > > > > > > > Thanks, > > > > > > > Dragos > > > > > > > > > > > > > > > Regards, > > > > > > > > -Siwei > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Jason, what do you think? > > > > > > > > > > > > > > > > > > Thanks! > > > > > > > > > > > > > > > > > > > --- > > > > > > > > > > drivers/vdpa/mlx5/net/mlx5_vnet.c | 9 +++++++++ > > > > > > > > > > include/linux/mlx5/mlx5_ifc_vdpa.h | 1 + > > > > > > > > > > 2 files changed, 10 insertions(+) > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > > > > > > > > > index f8f088cced50..80e066de0866 100644 > > > > > > > > > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c > > > > > > > > > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > > > > > > > > > @@ -1209,6 +1209,7 @@ static int modify_virtqueue(struct mlx5_vdpa_net *ndev, > > > > > > > > > > bool state_change = false; > > > > > > > > > > void *obj_context; > > > > > > > > > > void *cmd_hdr; > > > > > > > > > > + void *vq_ctx; > > > > > > > > > > void *in; > > > > > > > > > > int err; > > > > > > > > > > > > > > > > > > > > @@ -1230,6 +1231,7 @@ static int modify_virtqueue(struct mlx5_vdpa_net *ndev, > > > > > > > > > > MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, uid, ndev->mvdev.res.uid); > > > > > > > > > > > > > > > > > > > > obj_context = MLX5_ADDR_OF(modify_virtio_net_q_in, in, obj_context); > > > > > > > > > > + vq_ctx = MLX5_ADDR_OF(virtio_net_q_object, obj_context, virtio_q_context); > > > > > > > > > > > > > > > > > > > > if (mvq->modified_fields & MLX5_VIRTQ_MODIFY_MASK_STATE) { > > > > > > > > > > if (!is_valid_state_change(mvq->fw_state, state, is_resumable(ndev))) { > > > > > > > > > > @@ -1241,6 +1243,12 @@ static int modify_virtqueue(struct mlx5_vdpa_net *ndev, > > > > > > > > > > state_change = true; > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > + if (mvq->modified_fields & MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_ADDRS) { > > > > > > > > > > + MLX5_SET64(virtio_q, vq_ctx, desc_addr, mvq->desc_addr); > > > > > > > > > > + MLX5_SET64(virtio_q, vq_ctx, used_addr, mvq->device_addr); > > > > > > > > > > + MLX5_SET64(virtio_q, vq_ctx, available_addr, mvq->driver_addr); > > > > > > > > > > + } > > > > > > > > > > + > > > > > > > > > > MLX5_SET64(virtio_net_q_object, obj_context, modify_field_select, mvq->modified_fields); > > > > > > > > > > err = mlx5_cmd_exec(ndev->mvdev.mdev, in, inlen, out, sizeof(out)); > > > > > > > > > > if (err) > > > > > > > > > > @@ -2202,6 +2210,7 @@ static int mlx5_vdpa_set_vq_address(struct vdpa_device *vdev, u16 idx, u64 desc_ > > > > > > > > > > mvq->desc_addr = desc_area; > > > > > > > > > > mvq->device_addr = device_area; > > > > > > > > > > mvq->driver_addr = driver_area; > > > > > > > > > > + mvq->modified_fields |= MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_ADDRS; > > > > > > > > > > return 0; > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > diff --git a/include/linux/mlx5/mlx5_ifc_vdpa.h b/include/linux/mlx5/mlx5_ifc_vdpa.h > > > > > > > > > > index b86d51a855f6..9594ac405740 100644 > > > > > > > > > > --- a/include/linux/mlx5/mlx5_ifc_vdpa.h > > > > > > > > > > +++ b/include/linux/mlx5/mlx5_ifc_vdpa.h > > > > > > > > > > @@ -145,6 +145,7 @@ enum { > > > > > > > > > > MLX5_VIRTQ_MODIFY_MASK_STATE = (u64)1 << 0, > > > > > > > > > > MLX5_VIRTQ_MODIFY_MASK_DIRTY_BITMAP_PARAMS = (u64)1 << 3, > > > > > > > > > > MLX5_VIRTQ_MODIFY_MASK_DIRTY_BITMAP_DUMP_ENABLE = (u64)1 << 4, > > > > > > > > > > + MLX5_VIRTQ_MODIFY_MASK_VIRTIO_Q_ADDRS = (u64)1 << 6, > > > > > > > > > > MLX5_VIRTQ_MODIFY_MASK_DESC_GROUP_MKEY = (u64)1 << 14, > > > > > > > > > > }; > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > 2.42.0 > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
