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

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Date:   Mon, 31 May 2021 07:59:14 +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 1/2] vdpa/mlx5: Support creating resources with uid == 0

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 :-)
> 
> 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];
>