linux-kernel - [PATCH v3 09/11] cxl/region: Lock decoders that need address translation

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Message-ID: <20250912144514.526441-10-rrichter@amd.com>
Date: Fri, 12 Sep 2025 16:45:11 +0200
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>,
	Joshua Hahn <joshua.hahnjy@...il.com>, Robert Richter <rrichter@....com>
Subject: [PATCH v3 09/11] cxl/region: Lock decoders that need address translation

There is only support to translate addresses from an endpoint to its
parent port, but not in the opposite direction from the parent to the
endpoint. Thus, the endpoint address range cannot be determined and
setup manually for a given SPA range of a region. If the parent
implements the ->to_hpa() callback, address translation is
needed. Then, forbid reprogramming of the decoders and lock them.

Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/core/region.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 9fb1e9508213..44ea59252ff0 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3497,6 +3497,16 @@ static int setup_address_translation(struct cxl_endpoint_decoder *cxled,
 		return -ENXIO;
 	}
 
+	/*
+	 * There is only support to translate from the endpoint to its
+	 * parent port, but not in the opposite direction from the
+	 * parent to the endpoint. Thus, the endpoint address range
+	 * cannot be determined and setup manually. If the address range
+	 * was translated and modified, forbid reprogramming of the
+	 * decoders and lock them.
+	 */
+	cxld->flags |= CXL_DECODER_F_LOCK;
+
 	ctx->hpa_range = range;
 	ctx->interleave_ways = ways;
 	ctx->interleave_granularity = gran;
-- 
2.39.5