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

Ben Cheatham
2026-01-22T20:37:41Z

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.

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
cxl/lib/libcxl.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++
cxl/lib/libcxl.sym | 3 ++
cxl/libcxl.h | 3 ++
3 files changed, 87 insertions(+)

diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
index be134a1..3c3d2af 100644
--- a/cxl/lib/libcxl.c
+++ b/cxl/lib/libcxl.c
@@ -5045,3 +5045,84 @@ 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;
+ bool exists = false;
+ size_t len;
+ char *path;
+
+ if (!ctx->cxl_debugfs)
+ return false;
+
+ path = calloc(PATH_MAX, sizeof(char));
+ if (!path)
+ return false;
+
+ len = snprintf(path, PATH_MAX, "%s/%s/inject_poison", ctx->cxl_debugfs,
+ cxl_memdev_get_devname(memdev));
+ if (len >= PATH_MAX) {
+ err(ctx, "%s: buffer too small\n",
+ cxl_memdev_get_devname(memdev));
+ goto out;
+ }
+
+ if (!access(path, F_OK))
+ exists = true;
+
+out:
+ 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;
+ char addr[32];
+ size_t len;
+ char *path;
+ int rc;
+
+ if (!ctx->cxl_debugfs)
+ return -ENOENT;
+
+ path = calloc(PATH_MAX, sizeof(char));
+ if (!path)
+ return -ENOMEM;
+
+ len = snprintf(path, PATH_MAX, "%s/%s/%s", ctx->cxl_debugfs,
+ cxl_memdev_get_devname(memdev),
+ clear ? "clear_poison" : "inject_poison");
+ if (len >= PATH_MAX) {
+ err(ctx, "%s: buffer too small\n",
+ cxl_memdev_get_devname(memdev));
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ 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));
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ rc = sysfs_write_attr(ctx, path, addr);
+
+out:
+ 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 c683b83..c636edb 100644
--- a/cxl/lib/libcxl.sym
+++ b/cxl/lib/libcxl.sym
@@ -309,4 +309,7 @@ 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_10;
diff --git a/cxl/libcxl.h b/cxl/libcxl.h
index faef62e..4d035f0 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