[PATCH v7 3/8] cxl/hdm: Add BI coherency support for endpoint decoders

[Davidlohr Bueso <dave@stgolabs.net>]

Cache the HDM decoder's Supported Coherency Models on struct cxl_hdm.
Region attach consults this to verify the HDM supports the region's
coherency type.

For uncommitted endpoint decoders, init_hdm_decoder() defaults
target_type from supported_coherency: Type 3 devices default to
HDM-DB when the HDM is device-coherent-only, HDM-H otherwise.

Pre-committed decoders with the BI bit set are not supported because
endpoint and port enumerations are independent -- at decoder
enumeration cxlds->bi is not yet known, so the topology cannot be
verified.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 drivers/cxl/core/core.h |  1 +
 drivers/cxl/core/hdm.c  | 35 ++++++++++++++++++++++++-----------
 drivers/cxl/cxl.h       |  8 +++++++-
 drivers/cxl/cxlmem.h    |  2 ++
 4 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index e36b55fd63bd..b7757de83012 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -215,6 +215,7 @@ struct cxl_hdm;
 int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
 			struct cxl_endpoint_dvsec_info *info);
 int cxl_port_get_possible_dports(struct cxl_port *port);
+enum cxl_decoder_type cxled_default_type(struct cxl_endpoint_decoder *cxled);
 
 #ifdef CONFIG_CXL_FEATURES
 struct cxl_feat_entry *
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 0c80b76a5f9b..9da8aa211609 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -87,6 +87,8 @@ static void parse_hdm_decoder_caps(struct cxl_hdm *cxlhdm)
 		cxlhdm->iw_cap_mask |= BIT(3) | BIT(6) | BIT(12);
 	if (FIELD_GET(CXL_HDM_DECODER_INTERLEAVE_16_WAY, hdm_cap))
 		cxlhdm->iw_cap_mask |= BIT(16);
+	cxlhdm->supported_coherency =
+		FIELD_GET(CXL_HDM_DECODER_SUPPORTED_COHERENCY_MASK, hdm_cap);
 }
 
 static bool should_emulate_decoders(struct cxl_endpoint_dvsec_info *info)
@@ -968,6 +970,19 @@ static int cxl_setup_hdm_decoder_from_dvsec(
 	return 0;
 }
 
+enum cxl_decoder_type cxled_default_type(struct cxl_endpoint_decoder *cxled)
+{
+	struct cxl_dev_state *cxlds = cxled_to_memdev(cxled)->cxlds;
+	struct cxl_port *port = cxled_to_port(cxled);
+	struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
+
+	if (cxlds->type == CXL_DEVTYPE_CLASSMEM &&
+	    cxlhdm->supported_coherency != CXL_HDM_DECODER_COHERENCY_DEV)
+		return CXL_DECODER_HOSTONLYMEM;
+
+	return CXL_DECODER_DEVMEM;
+}
+
 static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 			    void __iomem *hdm, int which,
 			    u64 *dpa_base, struct cxl_endpoint_dvsec_info *info)
@@ -1023,6 +1038,14 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 		else
 			cxld->target_type = CXL_DECODER_DEVMEM;
 
+		/*
+		 * Autocommit BI-enabled decoders is not supported.
+		 * At this point cxlds->bi is not yet setup, so there
+		 * are no guarantees that the platform supports BI.
+		 */
+		if (FIELD_GET(CXL_HDM_DECODER0_CTRL_BI, ctrl))
+			return -ENXIO;
+
 		guard(rwsem_write)(&cxl_rwsem.region);
 		if (cxld->id != cxl_num_decoders_committed(port)) {
 			dev_warn(&port->dev,
@@ -1040,17 +1063,7 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 		port->commit_end = cxld->id;
 	} else {
 		if (cxled) {
-			struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-			struct cxl_dev_state *cxlds = cxlmd->cxlds;
-
-			/*
-			 * Default by devtype until a device arrives that needs
-			 * more precision.
-			 */
-			if (cxlds->type == CXL_DEVTYPE_CLASSMEM)
-				cxld->target_type = CXL_DECODER_HOSTONLYMEM;
-			else
-				cxld->target_type = CXL_DECODER_DEVMEM;
+			cxld->target_type = cxled_default_type(cxled);
 		} else {
 			/* To be overridden by region type at commit time */
 			cxld->target_type = CXL_DECODER_HOSTONLYMEM;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index d00b8b7b778a..c323c38d0da2 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -50,7 +50,7 @@ extern const struct nvdimm_security_ops *cxl_security_ops;
 #define CXL_BI_RT_CAPABILITY_LENGTH 0xC
 #define CXL_BI_DECODER_CAPABILITY_LENGTH 0xC
 
-/* HDM decoders CXL 2.0 8.2.5.12 CXL HDM Decoder Capability Structure */
+/* HDM decoders CXL 4.0 8.2.4.20 CXL HDM Decoder Capability Structure */
 #define CXL_HDM_DECODER_CAP_OFFSET 0x0
 #define   CXL_HDM_DECODER_COUNT_MASK GENMASK(3, 0)
 #define   CXL_HDM_DECODER_TARGET_COUNT_MASK GENMASK(7, 4)
@@ -58,6 +58,11 @@ extern const struct nvdimm_security_ops *cxl_security_ops;
 #define   CXL_HDM_DECODER_INTERLEAVE_14_12 BIT(9)
 #define   CXL_HDM_DECODER_INTERLEAVE_3_6_12_WAY BIT(11)
 #define   CXL_HDM_DECODER_INTERLEAVE_16_WAY BIT(12)
+#define   CXL_HDM_DECODER_SUPPORTED_COHERENCY_MASK GENMASK(22, 21)
+#define     CXL_HDM_DECODER_COHERENCY_UNKNOWN 0x0
+#define     CXL_HDM_DECODER_COHERENCY_DEV 0x1
+#define     CXL_HDM_DECODER_COHERENCY_HOST 0x2
+#define     CXL_HDM_DECODER_COHERENCY_BOTH 0x3
 #define CXL_HDM_DECODER_CTRL_OFFSET 0x4
 #define   CXL_HDM_DECODER_ENABLE BIT(1)
 #define CXL_HDM_DECODER0_BASE_LOW_OFFSET(i) (0x20 * (i) + 0x10)
@@ -72,6 +77,7 @@ extern const struct nvdimm_security_ops *cxl_security_ops;
 #define   CXL_HDM_DECODER0_CTRL_COMMITTED BIT(10)
 #define   CXL_HDM_DECODER0_CTRL_COMMIT_ERROR BIT(11)
 #define   CXL_HDM_DECODER0_CTRL_HOSTONLY BIT(12)
+#define   CXL_HDM_DECODER0_CTRL_BI BIT(13)
 #define CXL_HDM_DECODER0_TL_LOW(i) (0x20 * (i) + 0x24)
 #define CXL_HDM_DECODER0_TL_HIGH(i) (0x20 * (i) + 0x28)
 #define CXL_HDM_DECODER0_SKIP_LOW(i) CXL_HDM_DECODER0_TL_LOW(i)
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index ed419d0c59f2..344424684cd6 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -859,6 +859,7 @@ int cxl_mem_sanitize(struct cxl_memdev *cxlmd, u16 cmd);
  * @target_count: for switch decoders, max downstream port targets
  * @interleave_mask: interleave granularity capability, see check_interleave_cap()
  * @iw_cap_mask: bitmask of supported interleave ways, see check_interleave_cap()
+ * @supported_coherency: HDM Decoder Capability supported coherency models
  * @port: mapped cxl_port, see devm_cxl_setup_hdm()
  */
 struct cxl_hdm {
@@ -867,6 +868,7 @@ struct cxl_hdm {
 	unsigned int target_count;
 	unsigned int interleave_mask;
 	unsigned long iw_cap_mask;
+	unsigned int supported_coherency;
 	struct cxl_port *port;
 };
 
-- 
2.39.5