linux-kernel - [PATCH v1 19/29] cxl/region: Use endpoint's HPA range to find the port's decoder

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Message-ID: <20250107141015.3367194-20-rrichter@amd.com>
Date: Tue, 7 Jan 2025 15:10:05 +0100
From: Robert Richter <rrichter@....com>
To: Alison Schofield <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Jonathan Cameron <jonathan.cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>, Davidlohr Bueso <dave@...olabs.net>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Gregory Price
	<gourry@...rry.net>, "Fabio M. De Francesco"
	<fabio.m.de.francesco@...ux.intel.com>, Terry Bowman <terry.bowman@....com>,
	Robert Richter <rrichter@....com>
Subject: [PATCH v1 19/29] cxl/region: Use endpoint's HPA range to find the port's decoder

For the implementation of address translation it might not be possible
to determine the root decoder in the early enumeration state since the
SPA range is still unknown. Instead, the endpoint's HPA range is known
and from there the topology can be traversed up to the root port while
the memory range is adjusted from one memory domain to the next up to
the root port.

In a first step, use endpoint's HPA range to find the port's decoder.
Without address translation there is HPA == SPA. Then, the HPA range
of the endpoint can be used instead of the root decoder's range as
both are the same.

Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/core/region.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index b7f6d8a83e4e..23b86de3d4e7 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -861,9 +861,8 @@ static int cxl_port_calc_hpa(struct cxl_port *port, struct cxl_decoder *cxld,
 
 static int match_auto_decoder(struct device *dev, void *data)
 {
-	struct cxl_region_params *p = data;
+	struct range *r, *hpa = data;
 	struct cxl_decoder *cxld;
-	struct range *r;
 
 	if (!is_switch_decoder(dev))
 		return 0;
@@ -871,7 +870,7 @@ static int match_auto_decoder(struct device *dev, void *data)
 	cxld = to_cxl_decoder(dev);
 	r = &cxld->hpa_range;
 
-	if (p->res && p->res->start == r->start && p->res->end == r->end)
+	if (hpa && hpa->start == r->start && hpa->end == r->end)
 		return 1;
 
 	return 0;
@@ -888,7 +887,7 @@ cxl_find_decoder_early(struct cxl_port *port,
 		return &cxled->cxld;
 
 	if (test_bit(CXL_REGION_F_AUTO, &cxlr->flags))
-		dev = device_find_child(&port->dev, &cxlr->params,
+		dev = device_find_child(&port->dev, &cxled->cxld.hpa_range,
 					match_auto_decoder);
 	else
 		dev = device_find_child(&port->dev, NULL, match_free_decoder);
-- 
2.39.5