On Wed, Aug 9, 2023 at 6:58 AM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote: > > > > On 8/7/2023 8:00 PM, Jason Wang wrote: > > On Fri, Aug 4, 2023 at 1:58 AM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote: > >> > >> > >> On 8/3/2023 1:03 AM, Jason Wang wrote: > >>> On Thu, Aug 3, 2023 at 1:13 AM Dragos Tatulea <dtatulea@xxxxxxxxxx> 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@xxxxxxxxxx> > >>>> Reviewed-by: Eugenio Pérez <eperezma@xxxxxxxxxx> > >>>> Reviewed-by: Gal Pressman <gal@xxxxxxxxxx> > >>>> --- > >>>> 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@xxxxxxxxxx/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. > > It looks to me we don't need a new ops. We can simply do set_map() > > twice > What does it mean, first set_map(0, -1ULL) with zero iotlb entry passed > in to destroy all iotlb mappings previously added, and second set_map(0, > -1ULL) to restore 1:1 DMA MR? But userspace (maybe a buggy one but > doesn't do harm) apart from vhost-vdpa itself can do unmap twice anyway, > this is supported today I think. Why there'll be such obscure > distinction, or what's the benefit to treat second .set_map() as > recreating 1:1 mapping? Ok, I think I miss some context. I agree that it's better to decouple memory mappings from the virtio reset. It helps to reduce the unnecessary memory transactions. It might require a new feature flag. Regarding the method of restoring to 1:1 DMA MR, it might be dangerous for (buggy) vhost-vDPA devices. Since its userspace doesn't set up any mapping it can explore the kernel with that via CVQ? Thanks > > > or do you mean it would be faster? > I think with .reset_map() we at least can avoid indefinite latency > hiccup from destroying and recreating 1:1 mapping with the unwarranted > 2rd unmap call. And .reset_map() should work with both .dma_map() and > .set_map() APIs with clear semantics. > > Regards, > -Siwei > > > > Thanks > > > >> Thanks, > >> -Siwei > >> > >>> commit 6f5312f801836e6af9bcbb0bdb44dc423e129206 > >>> Author: Eli Cohen <elic@xxxxxxxxxx> > >>> 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@xxxxxxxxxx> > >>> Link: https://lore.kernel.org/r/20210602085854.62690-1-elic@xxxxxxxxxx > >>> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > >>> Acked-by: Jason Wang <jasowang@xxxxxxxxxx> > >>> > >>> 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@xxxxxxxxxxxxxxxxxxxxxxxxxx > >>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization