Re: [RFC 5/5] cxl: Avoid to create dax regions for type2 accelerators

Gregory Price
2024-10-01T13:58:17Z

On Wed, Sep 25, 2024 at 10:46:47AM +0800, Huang Ying wrote:
> The memory range of a type2 accelerator should be managed by the type2
> accelerator specific driver instead of the common dax region drivers,
> as discussed in [1].
>
> [1] https://lore.kernel.org/linux-cxl/66469ff1b8fbc_2c2629427@dwillia2-xfh.jf.intel.com.notmuch/
>
> So, in this patch, we skip dax regions creation for type2 accelerator
> device memory regions.
>
> Based on: https://lore.kernel.org/linux-cxl/168592159835.1948938.1647215579839222774.stgit@dwillia2-xfh.jf.intel.com/
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Co-developed-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Alejandro Lucero <alucerop@amd.com>
> ---
> drivers/cxl/core/region.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>

Reviewed-by: Gregory Price <gourry@gourry.net>

> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 9c68ec445128..b276752c38da 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3466,6 +3466,14 @@ static int cxl_region_probe(struct device *dev)
> p->res->start, p->res->end, cxlr,
> is_system_ram) > 0)
> return 0;
> + /*
> + * Accelerator regions have specific usage, skip
> + * device-dax registration.
> + */
> + if (cxlr->type == CXL_DECODER_ACCEL)
> + return 0;
> +
> + /* Expander routes to device-dax */
> return devm_cxl_add_dax_region(cxlr);
> default:
> dev_dbg(&cxlr->dev, "unsupported region mode: %d\n",
> --
> 2.39.2
>