From d01149bbe76d81d360ed24853d5247fcaad873e4 Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Wed, 14 Jan 2026 17:48:23 +0100 Subject: [PATCH] cxl/region: Use region data to get the root decoder To find a region's root decoder, the endpoint's HPA range is used to search the matching decoder by its range. With address translation the endpoint decoder's range is in a different address space and thus cannot be used to determine the root decoder. The region parameters are encapsulated within struct cxl_region_context and may include the translated Host Physical Address (HPA) range. Use this context to identify the root decoder rather than relying on the endpoint. Modify cxl_find_root_decoder() and add the region context as parameter. Rename this function to get_cxl_root_decoder() as a counterpart to put_cxl_root_decoder(). Simplify the implementation by removing function cxl_port_find_switch_decode(). The function is unnecessary because it is not referenced or utilized elsewhere in the code. Reviewed-by: Dave Jiang Reviewed-by: Jonathan Cameron Reviewed-by: Alison Schofield Tested-by: Gregory Price Signed-off-by: Robert Richter Link: https://patch.msgid.link/20260114164837.1076338-8-rrichter@amd.com Signed-off-by: Dave Jiang --- drivers/cxl/core/region.c | 50 +++++++++++++++++++-------------------- 1 file changed, 24 insertions(+), 26 deletions(-) diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 60d2d1dae2aa3..912796fd708e7 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -3469,47 +3469,44 @@ err: return rc; } -static int match_decoder_by_range(struct device *dev, const void *data) +static int match_root_decoder(struct device *dev, const void *data) { const struct range *r1, *r2 = data; - struct cxl_decoder *cxld; + struct cxl_root_decoder *cxlrd; - if (!is_switch_decoder(dev)) + if (!is_root_decoder(dev)) return 0; - cxld = to_cxl_decoder(dev); - r1 = &cxld->hpa_range; - return range_contains(r1, r2); -} - -static struct cxl_decoder * -cxl_port_find_switch_decoder(struct cxl_port *port, struct range *hpa_range) -{ - struct device *cxld_dev = device_find_child(&port->dev, hpa_range, - match_decoder_by_range); + cxlrd = to_cxl_root_decoder(dev); + r1 = &cxlrd->cxlsd.cxld.hpa_range; - return cxld_dev ? to_cxl_decoder(cxld_dev) : NULL; + return range_contains(r1, r2); } +/* + * Note, when finished with the device, drop the reference with + * put_device() or use the put_cxl_root_decoder helper. + */ static struct cxl_root_decoder * -cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled) +get_cxl_root_decoder(struct cxl_endpoint_decoder *cxled, + struct cxl_region_context *ctx) { struct cxl_memdev *cxlmd = cxled_to_memdev(cxled); struct cxl_port *port = cxled_to_port(cxled); struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port); - struct cxl_decoder *root, *cxld = &cxled->cxld; - struct range *hpa_range = &cxld->hpa_range; + struct device *cxlrd_dev; - root = cxl_port_find_switch_decoder(&cxl_root->port, hpa_range); - if (!root) { + cxlrd_dev = device_find_child(&cxl_root->port.dev, &ctx->hpa_range, + match_root_decoder); + if (!cxlrd_dev) { dev_err(cxlmd->dev.parent, "%s:%s no CXL window for range %#llx:%#llx\n", - dev_name(&cxlmd->dev), dev_name(&cxld->dev), - hpa_range->start, hpa_range->end); - return NULL; + dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev), + ctx->hpa_range.start, ctx->hpa_range.end); + return ERR_PTR(-ENXIO); } - return to_cxl_root_decoder(&root->dev); + return to_cxl_root_decoder(cxlrd_dev); } static int match_region_by_range(struct device *dev, const void *data) @@ -3706,9 +3703,10 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled) }; struct cxl_root_decoder *cxlrd __free(put_cxl_root_decoder) = - cxl_find_root_decoder(cxled); - if (!cxlrd) - return -ENXIO; + get_cxl_root_decoder(cxled, &ctx); + + if (IS_ERR(cxlrd)) + return PTR_ERR(cxlrd); /* * Ensure that, if multiple threads race to construct_region() -- 2.47.3