Re: [PATCH v3 17/20] cxl: allow region creation by type2 drivers

Jonathan Cameron
2024-09-13T18:08:13Z

On Sat, 7 Sep 2024 09:18:33 +0100
alejandro.lucero-palau@amd.com wrote:

> From: Alejandro Lucero <alucerop@amd.com>
>
> Creating a CXL region requires userspace intervention through the cxl
> sysfs files. Type2 support should allow accelerator drivers to create
> such cxl region from kernel code.
>
> Adding that functionality and integrating it with current support for
> memory expanders.
>
> Based on https://lore.kernel.org/linux-cxl/168592159835.1948938.1647215579839222774.stgit@dwillia2-xfh.jf.intel.com/
>
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Sign off doesn't make sense given Dan didn't sent the mail. Co-developed missing?

Minor stuff inline,

Jonathan

> +static struct cxl_region *construct_region_begin(struct cxl_root_decoder *cxlrd,
> + struct cxl_endpoint_decoder *cxled)
> {
> struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> - struct cxl_port *port = cxlrd_to_port(cxlrd);
> - struct range *hpa = &cxled->cxld.hpa_range;
> struct cxl_region_params *p;
> struct cxl_region *cxlr;
> - struct resource *res;
> - int rc;
> + int err = 0;
>
> do {
> cxlr = __create_region(cxlrd, cxled->mode,
> @@ -3404,8 +3414,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
> } while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
>
> if (IS_ERR(cxlr)) {
> - dev_err(cxlmd->dev.parent,
> - "%s:%s: %s failed assign region: %ld\n",
> + dev_err(cxlmd->dev.parent, "%s:%s: %s failed assign region: %ld\n",
> dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
> __func__, PTR_ERR(cxlr));
> return cxlr;
> @@ -3415,19 +3424,41 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
> p = &cxlr->params;
> if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) {
> dev_err(cxlmd->dev.parent,
> - "%s:%s: %s autodiscovery interrupted\n",
> + "%s:%s: %s region setup interrupted\n",
> dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
> __func__);
> - rc = -EBUSY;
> - goto err;
> + err = -EBUSY;
> }
>
> + if (err) {
> + construct_region_end();

Here I'd just release the semaphore not call this warpper as it's taken within this
function I think?

> + drop_region(cxlr);
> + return ERR_PTR(err);
> + }
> + return cxlr;
> +}
> +

> *res = DEFINE_RES_MEM_NAMED(hpa->start, range_len(hpa),
> @@ -3444,6 +3475,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
> __func__, dev_name(&cxlr->dev));
> }
>
> + p = &cxlr->params;
> p->res = res;
> p->interleave_ways = cxled->cxld.interleave_ways;
> p->interleave_granularity = cxled->cxld.interleave_granularity;
> @@ -3451,24 +3483,106 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>
> rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
> if (rc)
> - goto err;
> + goto out;
>
> dev_dbg(cxlmd->dev.parent, "%s:%s: %s %s res: %pr iw: %d ig: %d\n",
> - dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev), __func__,
> - dev_name(&cxlr->dev), p->res, p->interleave_ways,
> - p->interleave_granularity);
> + dev_name(&cxlmd->dev),
> + dev_name(&cxled->cxld.dev), __func__,
Avoid reformatting unless necessary. Hard to tell what changed
if anything.
> + dev_name(&cxlr->dev), p->res,
> + p->interleave_ways,
> + p->interleave_granularity);
>
> /* ...to match put_device() in cxl_add_to_region() */
> get_device(&cxlr->dev);
> up_write(&cxl_region_rwsem);
>
> +out:
> + construct_region_end();

As below. I'd have separate error handling path.
Same in the other paths.

> + if (rc) {
> + drop_region(cxlr);
> + return ERR_PTR(rc);
> + }
> return cxlr;
> +}
>
> -err:
> - up_write(&cxl_region_rwsem);
> - devm_release_action(port->uport_dev, unregister_region, cxlr);
> - return ERR_PTR(rc);
> +static struct cxl_region *
> +__construct_new_region(struct cxl_root_decoder *cxlrd,
> + struct cxl_endpoint_decoder *cxled)
> +{
> + struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
> + struct cxl_region_params *p;
> + resource_size_t size = 0;
set in all paths that use it.

> + struct cxl_region *cxlr;
> + int rc;
> +
> + cxlr = construct_region_begin(cxlrd, cxled);
> + if (IS_ERR(cxlr))
> + return cxlr;
> +
> + rc = set_interleave_ways(cxlr, 1);
> + if (rc)
> + goto out;
> +
> + rc = set_interleave_granularity(cxlr, cxld->interleave_granularity);
> + if (rc)
> + goto out;
> +
> + size = resource_size(cxled->dpa_res);
> +
only used once
rc = alloc_hpa(cxlr, resource_size(cxled->dpa_res));

> + rc = alloc_hpa(cxlr, size);
> + if (rc)
> + goto out;
> +
> + down_read(&cxl_dpa_rwsem);
> + rc = cxl_region_attach(cxlr, cxled, 0);
> + up_read(&cxl_dpa_rwsem);
> +
> + if (rc)
> + goto out;
> +
> + rc = cxl_region_decode_commit(cxlr);
> + if (rc)
> + goto out;
> +
> + p = &cxlr->params;
> + p->state = CXL_CONFIG_COMMIT;
> +out:

I'd break out a separate error handling path and
just duplicate the next line.

> + construct_region_end();
> + if (rc) {
> + drop_region(cxlr);
> + return ERR_PTR(rc);
> + }
> + return cxlr;
> +}