[PATCH v3 2/2] cxl/test: Add a 2-way 16K root decoder for passthrough testing

The cxl-test topologies do not provide a configuration where pass-
through decoders compute a granularity above the 16K max encodable
in hardware. The widest power-of-2 root decoder currently available
is 2-way at 4K granularity, so a passthrough decoder below it
computes at most 16K.

Add a CFMWS entry for a 2-way root decoder at 16K granularity. This
topology supports a region configuration spanning the two multi-port
host bridges and placing one endpoint under each bridge. The
intermediate switch decoders are then passthrough decoders with a
computed granularity of 32K.

This allows a CXL unit test to be added for this case.

Place the new window in the XOR topology set so the default modulo
topology used by most cxl-test coverage is unchanged.

Assisted-by: Claude:Opus-4-8
Signed-off-by: Alison Schofield <[email protected]>
---
 tools/testing/cxl/test/cxl.c | 48 ++++++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index ef92dd35e030..5b87a3f5673f 100644
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -188,10 +188,18 @@ static struct {
 		struct acpi_cedt_cfmws cfmws;
 		u32 target[3];
 	} cfmws8;
+	struct {
+		struct acpi_cedt_cfmws cfmws;
+		u32 target[2];
+	} cfmws9;
 	struct {
 		struct acpi_cedt_cxims cxims;
 		u64 xormap_list[2];
 	} cxims0;
+	struct {
+		struct acpi_cedt_cxims cxims;
+		u64 xormap_list[1];
+	} cxims1;
 } __packed mock_cedt = {
 	.cedt = {
 		.header = {
@@ -371,6 +379,28 @@ static struct {
 		},
 		.target = { 0, 1, 2, },
 	},
+	/*
+	 * A 2-way root at 16K granularity. A passthrough decoder below this
+	 * root computes a 32K granularity (16K * 2), which exceeds the maximum
+	 * encodable in hardware. It exercises the passthrough granularity path
+	 * in cxl_port_setup_targets().
+	 */
+	.cfmws9 = {
+		.cfmws = {
+			.header = {
+				.type = ACPI_CEDT_TYPE_CFMWS,
+				.length = sizeof(mock_cedt.cfmws9),
+			},
+			.interleave_arithmetic = ACPI_CEDT_CFMWS_ARITHMETIC_XOR,
+			.interleave_ways = 1,
+			.granularity = 6,
+			.restrictions = ACPI_CEDT_CFMWS_RESTRICT_HOSTONLYMEM |
+					ACPI_CEDT_CFMWS_RESTRICT_PMEM,
+			.qtg_id = FAKE_QTG_ID,
+			.window_size = SZ_256M * 8UL,
+		},
+		.target = { 0, 1, },
+	},
 	.cxims0 = {
 		.cxims = {
 			.header = {
@@ -382,6 +412,18 @@ static struct {
 		},
 		.xormap_list = { 0x404100, 0x808200, },
 	},
+	/* CXIMS for the 16K (hbig = 6) 2-way root, cfmws9 */
+	.cxims1 = {
+		.cxims = {
+			.header = {
+				.type = ACPI_CEDT_TYPE_CXIMS,
+				.length = sizeof(mock_cedt.cxims1),
+			},
+			.hbig = 6,
+			.nr_xormaps = 1,
+		},
+		.xormap_list = { 0x0, },
+	},
 };
 
 struct acpi_cedt_cfmws *mock_cfmws[] = {
@@ -395,6 +437,7 @@ struct acpi_cedt_cfmws *mock_cfmws[] = {
 	[6] = &mock_cedt.cfmws6.cfmws,
 	[7] = &mock_cedt.cfmws7.cfmws,
 	[8] = &mock_cedt.cfmws8.cfmws,
+	[9] = &mock_cedt.cfmws9.cfmws,
 };
 
 static int cfmws_start;
@@ -402,10 +445,11 @@ static int cfmws_end;
 #define CFMWS_MOD_ARRAY_START 0
 #define CFMWS_MOD_ARRAY_END   5
 #define CFMWS_XOR_ARRAY_START 6
-#define CFMWS_XOR_ARRAY_END   8
+#define CFMWS_XOR_ARRAY_END   9
 
-struct acpi_cedt_cxims *mock_cxims[1] = {
+struct acpi_cedt_cxims *mock_cxims[2] = {
 	[0] = &mock_cedt.cxims0.cxims,
+	[1] = &mock_cedt.cxims1.cxims,
 };
 
 struct cxl_mock_res {
-- 
2.37.3