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

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Date:   Mon, 31 May 2021 11:06:59 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Eli Cohen <elic@...dia.com>, 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 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.

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];