在 2021/6/1 上午11:40, Eli Cohen 写道:
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 <[email protected]>
---
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.


So we have:

static int _mlx5_vdpa_create_mr(struct mlx5_vdpa_dev *mvdev, struct vhost_iotlb *iotlb)
{
        struct mlx5_vdpa_mr *mr = &mvdev->mr;
        int err;

        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;
}

It looks to me we need to check err before set mr->initialized.

Thanks



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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