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

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Message-Id: <20250326074450.937819-1-lizhijian@fujitsu.com>
Date: Wed, 26 Mar 2025 15:44:50 +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>
Subject: [PATCH] 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

This patch also wraps some sanity checks into a function.

Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
 drivers/cxl/acpi.c | 45 +++++++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index cb14829bb9be..4a82d2d8b547 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);
@@ -468,8 +466,35 @@ struct cxl_chbs_context {
 	u32 cxl_version;
 	int nr_versions;
 	u32 saved_version;
+	u32 length;
 };
 
+static bool cxl_chbs_verify(struct device *dev, struct cxl_chbs_context ctx)
+{
+	if (ctx.cxl_version == UINT_MAX) {
+		dev_warn(dev, "No CHBS found for Host Bridge (UID %lld)\n",
+			 ctx.uid);
+		return false;
+	}
+
+	if (ctx.base == CXL_RESOURCE_NONE) {
+		dev_warn(dev, "CHBS invalid for Host Bridge (UID %lld)\n",
+			 ctx.uid);
+		return false;
+	}
+
+	if ((ctx.cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11 &&
+	     ctx.length != ACPI_CEDT_CHBS_LENGTH_CXL11) ||
+	    (ctx.cxl_version == ACPI_CEDT_CHBS_VERSION_CXL20 &&
+	     ctx.length != ACPI_CEDT_CHBS_LENGTH_CXL20)) {
+		dev_warn(dev, "Invalid length for Host Bridge (UID %lld)\n",
+			 ctx.uid);
+		return false;
+	}
+
+	return true;
+}
+
 static int cxl_get_chbs_iter(union acpi_subtable_headers *header, void *arg,
 			     const unsigned long end)
 {
@@ -478,10 +503,6 @@ 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)
-		return 0;
-
 	if (!chbs->base)
 		return 0;
 
@@ -502,6 +523,7 @@ static int cxl_get_chbs_iter(union acpi_subtable_headers *header, void *arg,
 
 	ctx->cxl_version = chbs->cxl_version;
 	ctx->base = chbs->base;
+	ctx->length = chbs->length;
 
 	return 0;
 }
@@ -570,17 +592,8 @@ static int add_host_bridge_dport(struct device *match, void *arg)
 	if (rc)
 		return rc;
 
-	if (ctx.cxl_version == UINT_MAX) {
-		dev_warn(match, "No CHBS found for Host Bridge (UID %lld)\n",
-			 ctx.uid);
-		return 0;
-	}
-
-	if (ctx.base == CXL_RESOURCE_NONE) {
-		dev_warn(match, "CHBS invalid for Host Bridge (UID %lld)\n",
-			 ctx.uid);
+	if (!cxl_chbs_verify(match, ctx))
 		return 0;
-	}
 
 	pci_root = acpi_pci_find_root(hb->handle);
 	bridge = pci_root->bus->bridge;
-- 
2.47.0