From: Saeed Mahameed <saeed@kernel.org>
To: Leon Romanovsky <leon@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
Or Har-Toov <ohartoov@nvidia.com>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
linux-rdma@vger.kernel.org,
Michael Guralnik <michaelgur@nvidia.com>,
netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>,
Saeed Mahameed <saeedm@nvidia.com>
Subject: Re: [PATCH mlx5-next 3/4] net/mlx5: Use query_special_contexts for mkeys
Date: Mon, 9 Jan 2023 14:31:32 -0800 [thread overview]
Message-ID: <Y7yVxD1eNYwx3VT0@x130> (raw)
In-Reply-To: <Y7qb1aeuGowalgzs@unreal>
On 08 Jan 12:32, Leon Romanovsky wrote:
>On Thu, Jan 05, 2023 at 04:58:22PM -0800, Saeed Mahameed wrote:
>> On 04 Jan 10:11, Leon Romanovsky wrote:
>> > From: Or Har-Toov <ohartoov@nvidia.com>
>> >
>> > Using query_sepcial_contexts in order to get the correct value of
>> > terminate_scatter_list_mkey, as FW will change it in some configurations.
>> > This is done one time when the device is loading and the value is being
>> > saved in the device context.
>> >
>> > Signed-off-by: Or Har-Toov <ohartoov@nvidia.com>
>> > Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
>> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
>> > ---
>> > .../net/ethernet/mellanox/mlx5/core/en_main.c | 2 +-
>> > .../net/ethernet/mellanox/mlx5/core/main.c | 27 +++++++++++++++++++
>> > include/linux/mlx5/driver.h | 1 +
>> > 3 files changed, 29 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
>> > index c76f15505a76..33d7a7095988 100644
>> > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
>> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
>> > @@ -826,7 +826,7 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
>> > if (rq->wqe.info.num_frags < (1 << rq->wqe.info.log_num_frags)) {
>> > wqe->data[f].byte_count = 0;
>> > wqe->data[f].lkey =
>> > - MLX5_TERMINATE_SCATTER_LIST_LKEY;
>> > + mdev->terminate_scatter_list_mkey;
>> > wqe->data[f].addr = 0;
>> > }
>> > }
>> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
>> > index 7f5db13e3550..d39d758744a0 100644
>> > --- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
>> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
>> > @@ -1221,6 +1221,28 @@ static int mlx5_function_teardown(struct mlx5_core_dev *dev, bool boot)
>> > return 0;
>> > }
>> >
>> > +static int mlx5_get_terminate_scatter_list_mkey(struct mlx5_core_dev *dev)
>> > +{
>> > + u32 out[MLX5_ST_SZ_DW(query_special_contexts_out)] = {};
>> > + u32 in[MLX5_ST_SZ_DW(query_special_contexts_in)] = {};
>> > + int err;
>> > +
>> > + MLX5_SET(query_special_contexts_in, in, opcode,
>> > + MLX5_CMD_OP_QUERY_SPECIAL_CONTEXTS);
>> > + err = mlx5_cmd_exec_inout(dev, query_special_contexts, in, out);
>> > + if (err)
>> > + return err;
>> > +
>> > + if (MLX5_CAP_GEN(dev, terminate_scatter_list_mkey)) {
>>
>> Why did you execute the command unconditionally if the output is only read
>> conditionally?
>>
>> early exit before executing the command, older FW might fail and driver will
>> be unusable ..
>
>According to the documentation, this functionality was forever, but you
>are presenting valid concern.
>
>>
>> > + dev->terminate_scatter_list_mkey =
>> > + cpu_to_be32(MLX5_GET(query_special_contexts_out, out,
>> > + terminate_scatter_list_mkey));
>> > + return 0;
>> > + }
>> > + dev->terminate_scatter_list_mkey = MLX5_TERMINATE_SCATTER_LIST_LKEY;
>>
>> Another concern, what happens with old driver that is using the hardcoded
>> value with newer fw ? will it fail ? will it be accepted ?
>
>It will be accepted and everything will work without glitches.
>FW keeps backward compatibility and use MLX5_TERMINATE_SCATTER_LIST_LKEY
>internally as a default.
>
Then please don't change mlx5e to use mdev->terminate_scatter_list_mkey in
this patch, just keep it as is and have a separate patch to change mlx5e.
next prev parent reply other threads:[~2023-01-09 22:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-04 8:11 [PATCH rdma-next 0/4] Rely on firmware to get special mkeys Leon Romanovsky
2023-01-04 8:11 ` [PATCH mlx5-next 1/4] net/mlx5: Expose bits for querying " Leon Romanovsky
2023-01-04 8:11 ` [PATCH mlx5-next 2/4] net/mlx5: Change define name for 0x100 lkey value Leon Romanovsky
2023-01-04 8:11 ` [PATCH mlx5-next 3/4] net/mlx5: Use query_special_contexts for mkeys Leon Romanovsky
2023-01-06 0:58 ` Saeed Mahameed
2023-01-08 10:32 ` Leon Romanovsky
2023-01-09 22:31 ` Saeed Mahameed [this message]
2023-01-04 8:11 ` [PATCH rdma-next 4/4] RDMA/mlx5: " Leon Romanovsky
2023-01-04 13:03 ` Jason Gunthorpe
2023-01-04 13:09 ` Leon Romanovsky
2023-01-04 13:13 ` Jason Gunthorpe
2023-01-04 13:55 ` Leon Romanovsky
2023-01-04 13:56 ` Jason Gunthorpe
2023-01-04 14:03 ` Leon Romanovsky
2023-01-06 1:04 ` Saeed Mahameed
2023-01-08 10:21 ` Leon Romanovsky
2023-01-09 22:24 ` Saeed Mahameed
2023-01-10 8:45 ` Leon Romanovsky
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