linux-kernel - [PATCH v3] cxl/acpi: Verify CHBS length for CXL2.0

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Message-Id: <20250410010545.99590-1-lizhijian@fujitsu.com>
Date: Thu, 10 Apr 2025 09:05:45 +0800
From: Li Zhijian <lizhijian@...itsu.com>
To: linux-cxl@...r.kernel.org
Cc: Jonathan Cameron <jonathan.cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>,
	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>,
	linux-kernel@...r.kernel.org,
	Li Zhijian <lizhijian@...itsu.com>,
	Gregory Price <gourry@...rry.net>
Subject: [PATCH v3] cxl/acpi: Verify CHBS length for CXL2.0

Per CXL Spec r3.1 Table 9-21, both CXL1.1 and CXL2.0 have defined their
own length, verify it to avoid an invalid CHBS.

Additionally, this patch also removes the redundant macro CXL_RCRB_SIZE,
favoring the use of `ACPI_CEDT_CHBS_LENGTH_CXL11`, which offers clearer
semantic meaning.

Reviewed-by: Gregory Price <gourry@...rry.net>
Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
V3:
 - say more words in removing CXL_RCRB_SIZE # Alison
 - Collected Reviewed-by
V2: don't factor out, just validate # Dan
---
 drivers/cxl/acpi.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index cb14829bb9be..2e63e50b2c40 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -11,8 +11,6 @@
 #include "cxlpci.h"
 #include "cxl.h"
 
-#define CXL_RCRB_SIZE	SZ_8K
-
 struct cxl_cxims_data {
 	int nr_maps;
 	u64 xormaps[] __counted_by(nr_maps);
@@ -478,8 +476,10 @@ static int cxl_get_chbs_iter(union acpi_subtable_headers *header, void *arg,
 
 	chbs = (struct acpi_cedt_chbs *) header;
 
-	if (chbs->cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11 &&
-	    chbs->length != CXL_RCRB_SIZE)
+	if ((chbs->cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11 &&
+	    chbs->length != ACPI_CEDT_CHBS_LENGTH_CXL11) ||
+	   (chbs->cxl_version == ACPI_CEDT_CHBS_VERSION_CXL20 &&
+	    chbs->length != ACPI_CEDT_CHBS_LENGTH_CXL20))
 		return 0;
 
 	if (!chbs->base)
-- 
2.47.0