Messages in this thread | | | Date | Thu, 3 Aug 2023 10:57:47 -0700 | Subject | Re: [PATCH 1/2] vdpa/mlx5: Fix mr->initialized semantics | From | Si-Wei Liu <> |
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On 8/3/2023 1:03 AM, Jason Wang wrote: > On Thu, Aug 3, 2023 at 1:13 AM Dragos Tatulea <dtatulea@nvidia.com> wrote: >> The mr->initialized flag is shared between the control vq and data vq >> part of the mr init/uninit. But if the control vq and data vq get placed >> in different ASIDs, it can happen that initializing the control vq will >> prevent the data vq mr from being initialized. >> >> This patch consolidates the control and data vq init parts into their >> own init functions. The mr->initialized will now be used for the data vq >> only. The control vq currently doesn't need a flag. >> >> The uninitializing part is also taken care of: mlx5_vdpa_destroy_mr got >> split into data and control vq functions which are now also ASID aware. >> >> Fixes: 8fcd20c30704 ("vdpa/mlx5: Support different address spaces for control and data") >> Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com> >> Reviewed-by: Eugenio Pérez <eperezma@redhat.com> >> Reviewed-by: Gal Pressman <gal@nvidia.com> >> --- >> drivers/vdpa/mlx5/core/mlx5_vdpa.h | 1 + >> drivers/vdpa/mlx5/core/mr.c | 97 +++++++++++++++++++++--------- >> 2 files changed, 71 insertions(+), 27 deletions(-) >> >> diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h >> index 25fc4120b618..a0420be5059f 100644 >> --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h >> +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h >> @@ -31,6 +31,7 @@ struct mlx5_vdpa_mr { >> struct list_head head; >> unsigned long num_directs; >> unsigned long num_klms; >> + /* state of dvq mr */ >> bool initialized; >> >> /* serialize mkey creation and destruction */ >> diff --git a/drivers/vdpa/mlx5/core/mr.c b/drivers/vdpa/mlx5/core/mr.c >> index 03e543229791..4ae14a248a4b 100644 >> --- a/drivers/vdpa/mlx5/core/mr.c >> +++ b/drivers/vdpa/mlx5/core/mr.c >> @@ -489,60 +489,103 @@ static void destroy_user_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr *mr >> } >> } >> >> -void mlx5_vdpa_destroy_mr(struct mlx5_vdpa_dev *mvdev) >> +static void _mlx5_vdpa_destroy_cvq_mr(struct mlx5_vdpa_dev *mvdev, unsigned int asid) >> +{ >> + if (mvdev->group2asid[MLX5_VDPA_CVQ_GROUP] != asid) >> + return; >> + >> + prune_iotlb(mvdev); >> +} >> + >> +static void _mlx5_vdpa_destroy_dvq_mr(struct mlx5_vdpa_dev *mvdev, unsigned int asid) >> { >> struct mlx5_vdpa_mr *mr = &mvdev->mr; >> >> - mutex_lock(&mr->mkey_mtx); >> + if (mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] != asid) >> + return; >> + >> if (!mr->initialized) >> - goto out; >> + return; >> >> - prune_iotlb(mvdev); >> if (mr->user_mr) >> destroy_user_mr(mvdev, mr); >> else >> destroy_dma_mr(mvdev, mr); >> >> mr->initialized = false; >> -out: >> +} >> + >> +static void mlx5_vdpa_destroy_mr_asid(struct mlx5_vdpa_dev *mvdev, unsigned int asid) >> +{ >> + struct mlx5_vdpa_mr *mr = &mvdev->mr; >> + >> + mutex_lock(&mr->mkey_mtx); >> + >> + _mlx5_vdpa_destroy_dvq_mr(mvdev, asid); >> + _mlx5_vdpa_destroy_cvq_mr(mvdev, asid); >> + >> mutex_unlock(&mr->mkey_mtx); >> } >> >> -static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, >> - struct vhost_iotlb *iotlb, unsigned int asid) >> +void mlx5_vdpa_destroy_mr(struct mlx5_vdpa_dev *mvdev) >> +{ >> + mlx5_vdpa_destroy_mr_asid(mvdev, mvdev->group2asid[MLX5_VDPA_CVQ_GROUP]); >> + mlx5_vdpa_destroy_mr_asid(mvdev, mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP]); >> +} >> + >> +static int _mlx5_vdpa_create_cvq_mr(struct mlx5_vdpa_dev *mvdev, >> + struct vhost_iotlb *iotlb, >> + unsigned int asid) >> +{ >> + if (mvdev->group2asid[MLX5_VDPA_CVQ_GROUP] != asid) >> + return 0; >> + >> + return dup_iotlb(mvdev, iotlb); > This worries me as conceptually, there should be no difference between > dvq mr and cvq mr. The virtqueue should be loosely coupled with mr. > > One example is that, if we only do dup_iotlb() but not try to create > dma mr here, we will break virtio-vdpa: For this case, I guess we may need another way to support virtio-vdpa 1:1 mapping rather than overloading virtio device reset semantics, see:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg953755.html
> Conceptually, the address mapping is not a part of the abstraction for > a virtio device now. So resetting the memory mapping during virtio > device reset seems wrong.
where we want to keep memory mapping intact across virtio device reset for best live migration latency/downtime. I wonder would it work to reset the mapping in vhost-vdpa life cycle out of virtio reset, say introduce a .reset_map() op to restore 1:1 mapping within vhost_vdpa_remove_as() right after vhost_vdpa_iotlb_unmap()? Then we can move the iotlb reset logic to there without worry breaking virtio-vdpa.
Thanks, -Siwei
> > commit 6f5312f801836e6af9bcbb0bdb44dc423e129206 > Author: Eli Cohen <elic@nvidia.com> > Date: Wed Jun 2 11:58:54 2021 +0300 > > vdpa/mlx5: Add support for running with virtio_vdpa > > In order to support running vdpa using vritio_vdpa driver, we need to > create a different kind of MR, one that has 1:1 mapping, since the > addresses referring to virtqueues are dma addresses. > > We create the 1:1 MR in mlx5_vdpa_dev_add() only in case firmware > supports the general capability umem_uid_0. The reason for that is that > 1:1 MRs must be created with uid == 0 while virtqueue objects can be > created with uid == 0 only when the firmware capability is on. > > If the set_map() callback is called with new translations provided > through iotlb, the driver will destroy the 1:1 MR and create a regular > one. > > Signed-off-by: Eli Cohen <elic@nvidia.com> > Link: https://lore.kernel.org/r/20210602085854.62690-1-elic@nvidia.com > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > Acked-by: Jason Wang <jasowang@redhat.com> > > Thanks > > >> +} >> + >> +static int _mlx5_vdpa_create_dvq_mr(struct mlx5_vdpa_dev *mvdev, >> + struct vhost_iotlb *iotlb, >> + unsigned int asid) >> { >> struct mlx5_vdpa_mr *mr = &mvdev->mr; >> int err; >> >> - if (mr->initialized) >> + if (mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] != asid) >> return 0; >> >> - if (mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] == asid) { >> - if (iotlb) >> - err = create_user_mr(mvdev, iotlb); >> - else >> - err = create_dma_mr(mvdev, mr); >> + if (mr->initialized) >> + return 0; >> >> - if (err) >> - return err; >> - } >> + if (iotlb) >> + err = create_user_mr(mvdev, iotlb); >> + else >> + err = create_dma_mr(mvdev, mr); >> >> - if (mvdev->group2asid[MLX5_VDPA_CVQ_GROUP] == asid) { >> - err = dup_iotlb(mvdev, iotlb); >> - if (err) >> - goto out_err; >> - } >> + if (err) >> + return err; >> >> mr->initialized = true; >> + >> + return 0; >> +} >> + >> +static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, >> + struct vhost_iotlb *iotlb, unsigned int asid) >> +{ >> + int err; >> + >> + err = _mlx5_vdpa_create_dvq_mr(mvdev, iotlb, asid); >> + if (err) >> + return err; >> + >> + err = _mlx5_vdpa_create_cvq_mr(mvdev, iotlb, asid); >> + if (err) >> + goto out_err; >> + >> return 0; >> >> out_err: >> - if (mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] == asid) { >> - if (iotlb) >> - destroy_user_mr(mvdev, mr); >> - else >> - destroy_dma_mr(mvdev, mr); >> - } >> + _mlx5_vdpa_destroy_dvq_mr(mvdev, asid); >> >> return err; >> } >> -- >> 2.41.0 >> > _______________________________________________ > Virtualization mailing list > Virtualization@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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