[PATCH v5 3/7] libcxl: Add poison injection support

[Ben Cheatham <Benjamin.Cheatham@amd.com>]

Add a library API for clearing and injecting poison into a CXL memory
device through the CXL debugfs.

This API will be used by the 'cxl-inject-error' and 'cxl-clear-error'
commands in later commits.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
 cxl/lib/libcxl.c   | 83 ++++++++++++++++++++++++++++++++++++++++++++++
 cxl/lib/libcxl.sym |  3 ++
 cxl/libcxl.h       |  3 ++
 3 files changed, 89 insertions(+)

diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
index af34db0..655eef0 100644
--- a/cxl/lib/libcxl.c
+++ b/cxl/lib/libcxl.c
@@ -5024,3 +5024,86 @@ CXL_EXPORT struct cxl_cmd *cxl_cmd_new_set_alert_config(struct cxl_memdev *memde
 {
 	return cxl_cmd_new_generic(memdev, CXL_MEM_COMMAND_ID_SET_ALERT_CONFIG);
 }
+
+CXL_EXPORT bool cxl_memdev_has_poison_injection(struct cxl_memdev *memdev)
+{
+	struct cxl_ctx *ctx = memdev->ctx;
+	size_t path_len, len;
+	bool exists = true;
+	char *path;
+	int rc;
+
+	if (!ctx->debugfs)
+		return false;
+
+	path_len = strlen(ctx->debugfs) + 100;
+	path = calloc(path_len, sizeof(char));
+	if (!path)
+		return false;
+
+	len = snprintf(path, path_len, "%s/cxl/%s/inject_poison", ctx->debugfs,
+		       cxl_memdev_get_devname(memdev));
+	if (len >= path_len) {
+		err(ctx, "%s: buffer too small\n",
+		    cxl_memdev_get_devname(memdev));
+		free(path);
+		return false;
+	}
+
+	rc = access(path, F_OK);
+	if (rc)
+		exists = false;
+
+	free(path);
+	return exists;
+}
+
+static int cxl_memdev_poison_action(struct cxl_memdev *memdev, size_t dpa,
+				    bool clear)
+{
+	struct cxl_ctx *ctx = memdev->ctx;
+	size_t path_len, len;
+	char addr[32];
+	char *path;
+	int rc;
+
+	if (!ctx->debugfs)
+		return -ENOENT;
+
+	path_len = strlen(ctx->debugfs) + 100;
+	path = calloc(path_len, sizeof(char));
+	if (!path)
+		return -ENOMEM;
+
+	len = snprintf(path, path_len, "%s/cxl/%s/%s", ctx->debugfs,
+		       cxl_memdev_get_devname(memdev),
+		       clear ? "clear_poison" : "inject_poison");
+	if (len >= path_len) {
+		err(ctx, "%s: buffer too small\n",
+		    cxl_memdev_get_devname(memdev));
+		free(path);
+		return -ENOMEM;
+	}
+
+	len = snprintf(addr, sizeof(addr), "0x%lx\n", dpa);
+	if (len >= sizeof(addr)) {
+		err(ctx, "%s: buffer too small\n",
+		    cxl_memdev_get_devname(memdev));
+		free(path);
+		return -ENOMEM;
+	}
+
+	rc = sysfs_write_attr(ctx, path, addr);
+	free(path);
+	return rc;
+}
+
+CXL_EXPORT int cxl_memdev_inject_poison(struct cxl_memdev *memdev, size_t addr)
+{
+	return cxl_memdev_poison_action(memdev, addr, false);
+}
+
+CXL_EXPORT int cxl_memdev_clear_poison(struct cxl_memdev *memdev, size_t addr)
+{
+	return cxl_memdev_poison_action(memdev, addr, true);
+}
diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
index 02d5119..3bce60d 100644
--- a/cxl/lib/libcxl.sym
+++ b/cxl/lib/libcxl.sym
@@ -304,4 +304,7 @@ global:
 	cxl_protocol_error_get_num;
 	cxl_protocol_error_get_str;
 	cxl_dport_protocol_error_inject;
+	cxl_memdev_has_poison_injection;
+	cxl_memdev_inject_poison;
+	cxl_memdev_clear_poison;
 } LIBCXL_9;
diff --git a/cxl/libcxl.h b/cxl/libcxl.h
index adb5716..56cba8f 100644
--- a/cxl/libcxl.h
+++ b/cxl/libcxl.h
@@ -105,6 +105,9 @@ int cxl_memdev_read_label(struct cxl_memdev *memdev, void *buf, size_t length,
 		size_t offset);
 int cxl_memdev_write_label(struct cxl_memdev *memdev, void *buf, size_t length,
 		size_t offset);
+bool cxl_memdev_has_poison_injection(struct cxl_memdev *memdev);
+int cxl_memdev_inject_poison(struct cxl_memdev *memdev, size_t dpa);
+int cxl_memdev_clear_poison(struct cxl_memdev *memdev, size_t dpa);
 struct cxl_cmd *cxl_cmd_new_get_fw_info(struct cxl_memdev *memdev);
 unsigned int cxl_cmd_fw_info_get_num_slots(struct cxl_cmd *cmd);
 unsigned int cxl_cmd_fw_info_get_active_slot(struct cxl_cmd *cmd);
-- 
2.52.0