linux-kernel - Re: [PATCH 1/2] vdpa/mlx5: Support creating resources with uid == 0

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Message-ID: <3717ebc5-66ce-2d50-1853-49442a8e71e1@redhat.com>
Date:   Mon, 31 May 2021 14:43:59 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Eli Cohen <elic@...dia.com>
Cc:     mst@...hat.com, virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] vdpa/mlx5: Support creating resources with uid == 0


在 2021/5/31 下午12:59, Eli Cohen 写道:
> On Mon, May 31, 2021 at 11:06:59AM +0800, Jason Wang wrote:
>> 在 2021/5/31 上午11:02, Jason Wang 写道:
>>> 在 2021/5/30 下午3:54, Eli Cohen 写道:
>>>> Currently all resources must be created with uid != 0 which is essential
>>>> userspace processes allocating virtquueue resources. Since this is a
>>>> kernel implementation, it is perfectly legal to open resources with
>>>> uid == 0.
>>>>
>>>> In case frimware supports, avoid allocating user context.
>>>
>>> Typo "frimware".
>>>
>>> Otherwise.
>>>
>>> Acked-by: Jason Wang <jasowang@...hat.com>
>>>
>>> (I don't see any code to check the firmware capability, is this
>>> intended?)
>>
>> Speak too fast. I see the MLX5_CAP_GEN(), so it's fine.
> And I responded too fast :-)


Right and thanks for the quick response :)


>> Thanks
>>
>>
>>> Thanks
>>>
>>>
>>>> Signed-off-by: Eli Cohen <elic@...dia.com>
>>>> ---
>>>>    drivers/vdpa/mlx5/core/resources.c | 6 ++++++
>>>>    include/linux/mlx5/mlx5_ifc.h      | 4 +++-
>>>>    2 files changed, 9 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/vdpa/mlx5/core/resources.c
>>>> b/drivers/vdpa/mlx5/core/resources.c
>>>> index 6521cbd0f5c2..836ab9ef0fa6 100644
>>>> --- a/drivers/vdpa/mlx5/core/resources.c
>>>> +++ b/drivers/vdpa/mlx5/core/resources.c
>>>> @@ -54,6 +54,9 @@ static int create_uctx(struct mlx5_vdpa_dev
>>>> *mvdev, u16 *uid)
>>>>        void *in;
>>>>        int err;
>>>>    +    if (MLX5_CAP_GEN(mvdev->mdev, umem_uid_0))
>>>> +        return 0;
>>>> +
>>>>        /* 0 means not supported */
>>>>        if (!MLX5_CAP_GEN(mvdev->mdev, log_max_uctx))
>>>>            return -EOPNOTSUPP;
>>>> @@ -79,6 +82,9 @@ static void destroy_uctx(struct mlx5_vdpa_dev
>>>> *mvdev, u32 uid)
>>>>        u32 out[MLX5_ST_SZ_DW(destroy_uctx_out)] = {};
>>>>        u32 in[MLX5_ST_SZ_DW(destroy_uctx_in)] = {};
>>>>    +    if (!uid)
>>>> +        return;
>>>> +
>>>>        MLX5_SET(destroy_uctx_in, in, opcode, MLX5_CMD_OP_DESTROY_UCTX);
>>>>        MLX5_SET(destroy_uctx_in, in, uid, uid);
>>>>    diff --git a/include/linux/mlx5/mlx5_ifc.h
>>>> b/include/linux/mlx5/mlx5_ifc.h
>>>> index 9c68b2da14c6..606d2aeacad4 100644
>>>> --- a/include/linux/mlx5/mlx5_ifc.h
>>>> +++ b/include/linux/mlx5/mlx5_ifc.h
>>>> @@ -1487,7 +1487,9 @@ struct mlx5_ifc_cmd_hca_cap_bits {
>>>>        u8         uar_4k[0x1];
>>>>        u8         reserved_at_241[0x9];
>>>>        u8         uar_sz[0x6];
>>>> -    u8         reserved_at_250[0x8];
>>>> +    u8         reserved_at_248[0x2];
>>>> +    u8         umem_uid_0[0x1];
>>>> +    u8         reserved_at_250[0x5];
>>>>        u8         log_pg_sz[0x8];
>>>>          u8         bf[0x1];