Re: [PATCH 1/3] cxl/pci: Ignore unknown register block types

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Fri, 16 Jul 2021 16:15:46 -0700
Ben Widawsky <ben.widawsky@intel.com> wrote:

> In an effort to explicit avoid supporting vendor specific register
> blocks (which can happily be mapped from userspace), entirely skip
> probing unknown types. The secondary benefit of this will be revealed
> in the future with code simplification.
> 
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Seems sensible even on it's own as we don't do anything with unknown
blocks anyway.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/cxl/pci.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index d7da18ebba81..dd0ac89fbdf4 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -1106,14 +1106,6 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
>  		u64 offset;
>  		u8 bar;
>  
> -		map = kzalloc(sizeof(*map), GFP_KERNEL);
> -		if (!map) {
> -			ret = -ENOMEM;
> -			goto free_maps;
> -		}
> -
> -		list_add(&map->list, &register_maps);
> -
>  		pci_read_config_dword(pdev, regloc, &reg_lo);
>  		pci_read_config_dword(pdev, regloc + 4, &reg_hi);
>  
> @@ -1123,6 +1115,18 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
>  		dev_dbg(dev, "Found register block in bar %u @ 0x%llx of type %u\n",
>  			bar, offset, reg_type);
>  
> +		/* Ignore unknown register block types */
> +		if (reg_type > CXL_REGLOC_RBI_MEMDEV)
> +			continue;
> +
> +		map = kzalloc(sizeof(*map), GFP_KERNEL);
> +		if (!map) {
> +			ret = -ENOMEM;
> +			goto free_maps;
> +		}
> +
> +		list_add(&map->list, &register_maps);
> +
>  		base = cxl_mem_map_regblock(cxlm, bar, offset);
>  		if (!base) {
>  			ret = -ENOMEM;