[v6,05/10] cxl/mem: Add debugfs attributes for poison inject and clear

Commit Message

Alison Schofield April 19, 2023, 3:26 a.m. UTC

From: Alison Schofield <[e-mail]>

Inject and Clear Poison commands are optionally supported by CXL
memdev devices and are intended for use in debug environments only.
Add debugfs attributes for user access.

Documentation/ABI/testing/debugfs-cxl describes the usage.

Signed-off-by: Alison Schofield <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
---
 Documentation/ABI/testing/debugfs-cxl | 35 +++++++++++++++++++++++++++
 drivers/cxl/mem.c                     | 28 +++++++++++++++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 Documentation/ABI/testing/debugfs-cxl

Patch

diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl
new file mode 100644
index 000000000000..fe61d372e3fa
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-cxl
@@ -0,0 +1,35 @@ 
+What:		/sys/kernel/debug/cxl/memX/inject_poison
+Date:		April, 2023
+KernelVersion:	v6.4
+Contact:	[e-mail]
+Description:
+		(WO) When a Device Physical Address (DPA) is written to this
+		attribute, the memdev driver sends an inject poison command to
+		the device for the specified address. The DPA must be 64-byte
+		aligned and the length of the injected poison is 64-bytes. If
+		successful, the device returns poison when the address is
+		accessed through the CXL.mem bus. Injecting poison adds the
+		address to the device's Poison List and the error source is set
+		to Injected. In addition, the device adds a poison creation
+		event to its internal Informational Event log, updates the
+		Event Status register, and if configured, interrupts the host.
+		It is not an error to inject poison into an address that
+		already has poison present and no error is returned. The
+		inject_poison attribute is only visible for devices supporting
+		the capability.
+
+
+What:		/sys/kernel/debug/memX/clear_poison
+Date:		April, 2023
+KernelVersion:	v6.4
+Contact:	[e-mail]
+Description:
+		(WO) When a Device Physical Address (DPA) is written to this
+		attribute, the memdev driver sends a clear poison command to
+		the device for the specified address. Clearing poison removes
+		the address from the device's Poison List and writes 0 (zero)
+		for 64 bytes starting at address. It is not an error to clear
+		poison from an address that does not have poison set. If the
+		device cannot clear poison from the address, -ENXIO is returned.
+		The clear_poison attribute is only visible for devices
+		supporting the capability.
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index b6a413facbd7..10caf180b3fa 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -94,6 +94,26 @@  static int devm_cxl_add_endpoint(struct device *host, struct cxl_memdev *cxlmd,
 	return 0;
 }
 
+static int cxl_debugfs_poison_inject(void *data, u64 dpa)
+{
+	struct cxl_memdev *cxlmd = data;
+
+	return cxl_inject_poison(cxlmd, dpa);
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_inject_fops, NULL,
+			 cxl_debugfs_poison_inject, "%llx\n");
+
+static int cxl_debugfs_poison_clear(void *data, u64 dpa)
+{
+	struct cxl_memdev *cxlmd = data;
+
+	return cxl_clear_poison(cxlmd, dpa);
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_clear_fops, NULL,
+			 cxl_debugfs_poison_clear, "%llx\n");
+
 static int cxl_mem_probe(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
@@ -117,6 +137,14 @@  static int cxl_mem_probe(struct device *dev)
 
 	dentry = cxl_debugfs_create_dir(dev_name(dev));
 	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);
+
+	if (test_bit(CXL_POISON_ENABLED_INJECT, cxlds->poison.enabled_cmds))
+		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
+				    &cxl_poison_inject_fops);
+	if (test_bit(CXL_POISON_ENABLED_CLEAR, cxlds->poison.enabled_cmds))
+		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
+				    &cxl_poison_clear_fops);
+
 	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
 	if (rc)
 		return rc;