Re: [PATCH] cxl: Deny Features commands on the RAW mailbox path

[Alison Schofield <alison.schofield@intel.com>]

On Wed, Jul 15, 2026 at 08:51:26AM -0700, Dave Jiang wrote:
> The RAW mailbox command path allows user to issue arbitrary opcodes
> to the device. The FWCTL interface was introduced to support the
> CXL Features commands where access control is provided depends on
> what the CEL indicates.
> 
> Add the Features commands to cxl_disabled_raw_commands[] to ensure
> that all Features commands are only accessible through the FWCTL
> interface.
> 
> The cxl_raw_allow_all debugfs override knob bypasses the disabled list
> if the user is aware of the risks and wants to use the RAW path for
> Features commands.


Reviewed-by: Alison Schofield <alison.schofield@intel.com>


> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/core/mbox.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index 7c6c5b7450a5..6dea70a1ff95 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -91,6 +91,10 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
>   *
>   * CXL_MBOX_OP_[GET_,INJECT_,CLEAR_]POISON: These commands require kernel
>   * driver orchestration for safety.
> + *
> + * CXL_MBOX_OP_[GET_SUPPORTED_FEATURES,GET_FEATURE,SET_FEATURE]: Features are
> + * accessed through the fwctl ABI, which applies scope-based access control.
> + * The RAW path would bypass those checks, so it is not permitted here.
>   */
>  static u16 cxl_disabled_raw_commands[] = {
>  	CXL_MBOX_OP_ACTIVATE_FW,
> @@ -102,6 +106,9 @@ static u16 cxl_disabled_raw_commands[] = {
>  	CXL_MBOX_OP_GET_POISON,
>  	CXL_MBOX_OP_INJECT_POISON,
>  	CXL_MBOX_OP_CLEAR_POISON,
> +	CXL_MBOX_OP_GET_SUPPORTED_FEATURES,
> +	CXL_MBOX_OP_GET_FEATURE,
> +	CXL_MBOX_OP_SET_FEATURE,
>  };
>  
>  /*
> 
> base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
> -- 
> 2.55.0
>