[RFC 1/3] libcxl: add interfaces for GET_POISON_LIST mailbox commands

[alison.schofield@intel.com]

From: Alison Schofield <alison.schofield@intel.com>

CXL devices maintain a list of locations that are poisoned or result
in poison if the addresses are accessed by the host.

Per the spec (CXL 3.0 8.2.9.8.4.1), the device returns this Poison
list as a set of  Media Error Records that include the source of the
error, the starting device physical address and length.

Trigger the retrieval of the poison list by writing to the device
sysfs attribute: trigger_poison_list.

The retrieval is offered by memdev or by region:
int cxl_memdev_trigger_poison_list(struct cxl_memdev *memdev);
int cxl_region_trigger_poison_list(struct cxl_region *region);

This interface only triggers the retrieval of the poison list
from the devices. Users need to use the kernel trace event
'cxl_poison' to collect and view the error records.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 cxl/lib/libcxl.c   | 40 ++++++++++++++++++++++++++++++++++++++++
 cxl/lib/libcxl.sym |  6 ++++++
 cxl/libcxl.h       |  2 ++
 3 files changed, 48 insertions(+)

diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
index e8c5d4444dd0..a99ac154b7d2 100644
--- a/cxl/lib/libcxl.c
+++ b/cxl/lib/libcxl.c
@@ -1331,6 +1331,46 @@ CXL_EXPORT int cxl_memdev_disable_invalidate(struct cxl_memdev *memdev)
 	return 0;
 }
 
+CXL_EXPORT int cxl_memdev_trigger_poison_list(struct cxl_memdev *memdev)
+{
+	struct cxl_ctx *ctx = cxl_memdev_get_ctx(memdev);
+	char *path = memdev->dev_buf;
+	int len = memdev->buf_len, rc;
+
+	if (snprintf(path, len, "%s/trigger_poison_list", memdev->dev_path) >= len) {
+		err(ctx, "%s: buffer too small\n",
+		    cxl_memdev_get_devname(memdev));
+		return -ENXIO;
+	}
+	rc = sysfs_write_attr(ctx, path, "1\n");
+	if (rc < 0) {
+		fprintf(stderr, "%s: Failed write sysfs attr trigger_poison_list\n",
+			cxl_memdev_get_devname(memdev));
+		return rc;
+	}
+	return 0;
+}
+
+CXL_EXPORT int cxl_region_trigger_poison_list(struct cxl_region *region)
+{
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	char *path = region->dev_buf;
+	int len = region->buf_len, rc;
+
+	if (snprintf(path, len, "%s/trigger_poison_list", region->dev_path) >= len) {
+		err(ctx, "%s: buffer too small\n",
+		    cxl_region_get_devname(region));
+		return -ENXIO;
+	}
+	rc = sysfs_write_attr(ctx, path, "1\n");
+	if (rc < 0) {
+		fprintf(stderr, "%s: Failed write sysfs attr trigger_poison_list\n",
+			cxl_region_get_devname(region));
+		return rc;
+	}
+	return 0;
+}
+
 CXL_EXPORT int cxl_memdev_enable(struct cxl_memdev *memdev)
 {
 	struct cxl_ctx *ctx = cxl_memdev_get_ctx(memdev);
diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
index 8bb91e05638b..ecf98e6c7af2 100644
--- a/cxl/lib/libcxl.sym
+++ b/cxl/lib/libcxl.sym
@@ -217,3 +217,9 @@ global:
 	cxl_decoder_get_max_available_extent;
 	cxl_decoder_get_region;
 } LIBCXL_2;
+
+LIBCXL_4 {
+global:
+	cxl_memdev_trigger_poison_list;
+	cxl_region_trigger_poison_list;
+} LIBCXL_3;
diff --git a/cxl/libcxl.h b/cxl/libcxl.h
index 9fe4e99263dd..5ebdf0879325 100644
--- a/cxl/libcxl.h
+++ b/cxl/libcxl.h
@@ -375,6 +375,8 @@ enum cxl_setpartition_mode {
 
 int cxl_cmd_partition_set_mode(struct cxl_cmd *cmd,
 		enum cxl_setpartition_mode mode);
+int cxl_memdev_trigger_poison_list(struct cxl_memdev *memdev);
+int cxl_region_trigger_poison_list(struct cxl_region *region);
 
 #ifdef __cplusplus
 } /* extern "C" */
-- 
2.37.3