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Message-ID: <20210601034018.GA203469@mtl-vdi-166.wap.labs.mlnx>
Date: Tue, 1 Jun 2021 06:40:18 +0300
From: Eli Cohen <elic@...dia.com>
To: Jason Wang <jasowang@...hat.com>
CC: <mst@...hat.com>, <virtualization@...ts.linux-foundation.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] vdpa/mlx5: Add support for running with virtio_vdpa
On Tue, Jun 01, 2021 at 10:09:45AM +0800, Jason Wang wrote:
>
> 在 2021/6/1 上午12:04, Eli Cohen 写道:
> > 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@...dia.com>
> > ---
> > v0 --> v1:
> > 1. Clear user_mr after successful creation of DMA MR
> > 2. Check return code of mlx5_vdpa_create_mr() and emit warning if
> > failed.
> >
> > drivers/vdpa/mlx5/core/mlx5_vdpa.h | 1 +
> > drivers/vdpa/mlx5/core/mr.c | 84 +++++++++++++++++++++++++-----
> > drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 +++++-
> > 3 files changed, 85 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> > index b6cc53ba980c..09a16a3d1b2a 100644
> > --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> > +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> > @@ -35,6 +35,7 @@ struct mlx5_vdpa_mr {
> > /* serialize mkey creation and destruction */
> > struct mutex mkey_mtx;
> > + bool user_mr;
> > };
> > struct mlx5_vdpa_resources {
> > diff --git a/drivers/vdpa/mlx5/core/mr.c b/drivers/vdpa/mlx5/core/mr.c
> > index 800cfd1967ad..3c6c1d846f5e 100644
> > --- a/drivers/vdpa/mlx5/core/mr.c
> > +++ b/drivers/vdpa/mlx5/core/mr.c
> > @@ -360,7 +360,7 @@ static int add_direct_chain(struct mlx5_vdpa_dev *mvdev, u64 start, u64 size, u8
> > * indirect memory key that provides access to the enitre address space given
> > * by iotlb.
> > */
> > -static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *iotlb)
> > +static int create_user_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *iotlb)
> > {
> > struct mlx5_vdpa_mr *mr = &mvdev->mr;
> > struct mlx5_vdpa_direct_mr *dmr;
> > @@ -374,9 +374,6 @@ static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb
> > int err = 0;
> > int nnuls;
> > - if (mr->initialized)
> > - return 0;
> > -
> > INIT_LIST_HEAD(&mr->head);
> > for (map = vhost_iotlb_itree_first(iotlb, start, last); map;
> > map = vhost_iotlb_itree_next(map, start, last)) {
> > @@ -414,7 +411,7 @@ static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb
> > if (err)
> > goto err_chain;
> > - mr->initialized = true;
> > + mr->user_mr = true;
> > return 0;
> > err_chain:
> > @@ -426,33 +423,92 @@ static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb
> > return err;
> > }
> > -int mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *iotlb)
> > +static int create_dma_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr *mr)
> > +{
> > + int inlen = MLX5_ST_SZ_BYTES(create_mkey_in);
> > + void *mkc;
> > + u32 *in;
> > + int err;
> > +
> > + in = kzalloc(inlen, GFP_KERNEL);
> > + if (!in)
> > + return -ENOMEM;
> > +
> > + mkc = MLX5_ADDR_OF(create_mkey_in, in, memory_key_mkey_entry);
> > +
> > + MLX5_SET(mkc, mkc, access_mode_1_0, MLX5_MKC_ACCESS_MODE_PA);
> > + MLX5_SET(mkc, mkc, length64, 1);
> > + MLX5_SET(mkc, mkc, lw, 1);
> > + MLX5_SET(mkc, mkc, lr, 1);
> > + MLX5_SET(mkc, mkc, pd, mvdev->res.pdn);
> > + MLX5_SET(mkc, mkc, qpn, 0xffffff);
> > +
> > + err = mlx5_vdpa_create_mkey(mvdev, &mr->mkey, in, inlen);
> > + if (!err)
> > + mr->user_mr = false;
>
>
> Rethink about this. I wonder this is correct when we fail to create memory
> key.
>
> In this case, user_mr is true but user_mr is already destroyed. Can this
> lead double free for user mr?
mr->user_mr is a binary flag and its sole purpose is to tell the flavour
of the MR but is valid only when mr->initialized is true. MR won't be
freed if mr->initialized is false.
>
> Thanks
>
>
> > +
> > + kfree(in);
> > + return err;
> > +}
> > +
> > +static void destroy_dma_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr *mr)
> > +{
> > + mlx5_vdpa_destroy_mkey(mvdev, &mr->mkey);
> > +}
> > +
> > +static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *iotlb)
> > {
> > struct mlx5_vdpa_mr *mr = &mvdev->mr;
> > int err;
> > - mutex_lock(&mr->mkey_mtx);
> > + if (mr->initialized)
> > + return 0;
> > +
> > + if (iotlb)
> > + err = create_user_mr(mvdev, iotlb);
> > + else
> > + err = create_dma_mr(mvdev, mr);
> > +
> > + mr->initialized = true;
> > + return err;
> > +}
> > +
> > +int mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *iotlb)
> > +{
> > + int err;
> > +
> > + mutex_lock(&mvdev->mr.mkey_mtx);
> > err = _mlx5_vdpa_create_mr(mvdev, iotlb);
> > - mutex_unlock(&mr->mkey_mtx);
> > + mutex_unlock(&mvdev->mr.mkey_mtx);
> > return err;
> > }
> > -void mlx5_vdpa_destroy_mr(struct mlx5_vdpa_dev *mvdev)
> > +static void destroy_user_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr *mr)
> > {
> > - struct mlx5_vdpa_mr *mr = &mvdev->mr;
> > struct mlx5_vdpa_direct_mr *dmr;
> > struct mlx5_vdpa_direct_mr *n;
> > - mutex_lock(&mr->mkey_mtx);
> > - if (!mr->initialized)
> > - goto out;
> > -
> > destroy_indirect_key(mvdev, mr);
> > list_for_each_entry_safe_reverse(dmr, n, &mr->head, list) {
> > list_del_init(&dmr->list);
> > unmap_direct_mr(mvdev, dmr);
> > kfree(dmr);
> > }
> > +}
> > +
> > +void mlx5_vdpa_destroy_mr(struct mlx5_vdpa_dev *mvdev)
> > +{
> > + struct mlx5_vdpa_mr *mr = &mvdev->mr;
> > +
> > + mutex_lock(&mr->mkey_mtx);
> > + if (!mr->initialized)
> > + goto out;
> > +
> > + if (mr->user_mr)
> > + destroy_user_mr(mvdev, mr);
> > + else
> > + destroy_dma_mr(mvdev, mr);
> > +
> > memset(mr, 0, sizeof(*mr));
> > mr->initialized = false;
> > out:
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index fdf3e74bffbd..02a05492204c 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -1780,6 +1780,10 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> > ndev->mvdev.status = 0;
> > ndev->mvdev.mlx_features = 0;
> > ++mvdev->generation;
> > + if (MLX5_CAP_GEN(mvdev->mdev, umem_uid_0)) {
> > + if (mlx5_vdpa_create_mr(mvdev, NULL))
> > + mlx5_vdpa_warn(mvdev, "create MR failed\n");
> > + }
> > return;
> > }
> > @@ -1859,6 +1863,7 @@ static void mlx5_vdpa_free(struct vdpa_device *vdev)
> > ndev = to_mlx5_vdpa_ndev(mvdev);
> > free_resources(ndev);
> > + mlx5_vdpa_destroy_mr(mvdev);
> > mlx5_vdpa_free_resources(&ndev->mvdev);
> > mutex_destroy(&ndev->reslock);
> > }
> > @@ -2023,9 +2028,15 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name)
> > if (err)
> > goto err_mtu;
> > + if (MLX5_CAP_GEN(mvdev->mdev, umem_uid_0)) {
> > + err = mlx5_vdpa_create_mr(mvdev, NULL);
> > + if (err)
> > + goto err_res;
> > + }
> > +
> > err = alloc_resources(ndev);
> > if (err)
> > - goto err_res;
> > + goto err_mr;
> > mvdev->vdev.mdev = &mgtdev->mgtdev;
> > err = _vdpa_register_device(&mvdev->vdev, 2 * mlx5_vdpa_max_qps(max_vqs));
> > @@ -2037,6 +2048,8 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name)
> > err_reg:
> > free_resources(ndev);
> > +err_mr:
> > + mlx5_vdpa_destroy_mr(mvdev);
> > err_res:
> > mlx5_vdpa_free_resources(&ndev->mvdev);
> > err_mtu:
>
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