RE: [PATCH v6 06/14] cxl: Setup exclusive CXL features that are reserved for the kernel

[Shiju Jose <shiju.jose@huawei.com>]

>-----Original Message-----
>From: Dave Jiang <dave.jiang@intel.com>
>Sent: 18 February 2025 22:55
>To: linux-cxl@vger.kernel.org
>Cc: dan.j.williams@intel.com; ira.weiny@intel.com; vishal.l.verma@intel.com;
>alison.schofield@intel.com; Jonathan Cameron
><jonathan.cameron@huawei.com>; dave@stgolabs.net; jgg@nvidia.com; Shiju
>Jose <shiju.jose@huawei.com>; saeed@kernel.org; Li Ming
><ming.li@zohomail.com>
>Subject: [PATCH v6 06/14] cxl: Setup exclusive CXL features that are reserved for
>the kernel
>
>Certain features will be exclusively used by components such as in kernel RAS
>driver. Setup an exclusion list that can be used to detect if a feature is exclusive
>to the kernel.
>
>Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>Reviewed-by: Li Ming <ming.li@zohomail.com>
>Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Tested-by: Shiju Jose <shiju.jose@huawei.com>

>---
> drivers/cxl/core/features.c | 28 ++++++++++++++++++++++++++++
> include/cxl/features.h      | 34 ++++++++++++++++++++++++++++++++++
> 2 files changed, 62 insertions(+)
>
>diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c index
>17a82734a340..048ba4fc3538 100644
>--- a/drivers/cxl/core/features.c
>+++ b/drivers/cxl/core/features.c
>@@ -7,6 +7,28 @@
> #include "core.h"
> #include "cxlmem.h"
>
>+/* All the features below are exclusive to the kernel */ static const
>+uuid_t cxl_exclusive_feats[] = {
>+	CXL_FEAT_PATROL_SCRUB_UUID,
>+	CXL_FEAT_ECS_UUID,
>+	CXL_FEAT_SPPR_UUID,
>+	CXL_FEAT_HPPR_UUID,
>+	CXL_FEAT_CACHELINE_SPARING_UUID,
>+	CXL_FEAT_ROW_SPARING_UUID,
>+	CXL_FEAT_BANK_SPARING_UUID,
>+	CXL_FEAT_RANK_SPARING_UUID,
>+};
>+
>+static bool is_cxl_feature_exclusive(struct cxl_feat_entry *entry) {
>+	for (int i = 0; i < ARRAY_SIZE(cxl_exclusive_feats); i++) {
>+		if (uuid_equal(&entry->uuid, &cxl_exclusive_feats[i]))
>+			return true;
>+	}
>+
>+	return false;
>+}
>+
> inline struct cxl_features_state *to_cxlfs(struct cxl_dev_state *cxlds)  {
> 	return cxlds->cxlfs;
>@@ -47,6 +69,7 @@ get_supported_features(struct cxl_features_state *cxlfs)
> 	struct cxl_mbox_get_sup_feats_in mbox_in;
> 	struct cxl_feat_entry *entry;
> 	struct cxl_mbox_cmd mbox_cmd;
>+	int user_feats = 0;
> 	int count;
>
> 	count = cxl_get_supported_features_count(cxl_mbox);
>@@ -121,6 +144,10 @@ get_supported_features(struct cxl_features_state
>*cxlfs)
> 			return NULL;
>
> 		memcpy(entry, mbox_out->ents, retrieved);
>+		for (int i = 0; i < num_entries; i++) {
>+			if (!is_cxl_feature_exclusive(entry + i))
>+				user_feats++;
>+		}
> 		entry += num_entries;
> 		/*
> 		 * If the number of output entries is less than expected, add the
>@@ -131,6 +158,7 @@ get_supported_features(struct cxl_features_state *cxlfs)
> 	} while (remain_feats);
>
> 	entries->num_features = count;
>+	entries->num_user_features = user_feats;
>
> 	return no_free_ptr(entries);
> }
>diff --git a/include/cxl/features.h b/include/cxl/features.h index
>ae56ef7ec9ab..d2cde46b0fec 100644
>--- a/include/cxl/features.h
>+++ b/include/cxl/features.h
>@@ -5,6 +5,39 @@
>
> #include <linux/uuid.h>
>
>+/* Feature UUIDs used by the kernel */
>+#define CXL_FEAT_PATROL_SCRUB_UUID
>		\
>+	UUID_INIT(0x96dad7d6, 0xfde8, 0x482b, 0xa7, 0x33, 0x75, 0x77, 0x4e,
>	\
>+		  0x06, 0xdb, 0x8a)
>+
>+#define CXL_FEAT_ECS_UUID
>	\
>+	UUID_INIT(0xe5b13f22, 0x2328, 0x4a14, 0xb8, 0xba, 0xb9, 0x69, 0x1e,
>	\
>+		  0x89, 0x33, 0x86)
>+
>+#define CXL_FEAT_SPPR_UUID
>	\
>+	UUID_INIT(0x892ba475, 0xfad8, 0x474e, 0x9d, 0x3e, 0x69, 0x2c, 0x91,
>	\
>+		  0x75, 0x68, 0xbb)
>+
>+#define CXL_FEAT_HPPR_UUID
>	\
>+	UUID_INIT(0x80ea4521, 0x786f, 0x4127, 0xaf, 0xb1, 0xec, 0x74, 0x59,
>	\
>+		  0xfb, 0x0e, 0x24)
>+
>+#define CXL_FEAT_CACHELINE_SPARING_UUID
>		\
>+	UUID_INIT(0x96C33386, 0x91dd, 0x44c7, 0x9e, 0xcb, 0xfd, 0xaf, 0x65,
>	\
>+		  0x03, 0xba, 0xc4)
>+
>+#define CXL_FEAT_ROW_SPARING_UUID
>		\
>+	UUID_INIT(0x450ebf67, 0xb135, 0x4f97, 0xa4, 0x98, 0xc2, 0xd5, 0x7f,
>	\
>+		  0x27, 0x9b, 0xed)
>+
>+#define CXL_FEAT_BANK_SPARING_UUID
>		\
>+	UUID_INIT(0x78b79636, 0x90ac, 0x4b64, 0xa4, 0xef, 0xfa, 0xac, 0x5d,
>	\
>+		  0x18, 0xa8, 0x63)
>+
>+#define CXL_FEAT_RANK_SPARING_UUID
>		\
>+	UUID_INIT(0x34dbaff5, 0x0552, 0x4281, 0x8f, 0x76, 0xda, 0x0b, 0x5e,
>	\
>+		  0x7a, 0x76, 0xa7)
>+
> /* Feature commands capability supported by a device */  enum
>cxl_features_capability {
> 	CXL_FEATURES_NONE = 0,
>@@ -134,6 +167,7 @@ struct cxl_features_state {
> 	struct cxl_dev_state *cxlds;
> 	struct cxl_feat_entries {
> 		int num_features;
>+		int num_user_features;
> 		struct cxl_feat_entry ent[] __counted_by(num_features);
> 	} *entries;
> };
>--
>2.48.1