[PATCH v13 3/4] cxl/core: Add CXL EINJ debugfs files

Ben Cheatham
2024-02-20T22:12:57Z

Export CXL helper functions in the einj_cxl module for getting/injecting
available CXL protocol error types to sysfs under kernel/debug/cxl.

The kernel/debug/cxl/einj_types file will print the available CXL
protocol errors in the same format as the available_error_types
file provided by the einj_cxl module. The
kernel/debug/cxl/$dport_dev/einj_inject is functionally the same as the
error_type and error_inject files provided by the EINJ module, i.e.:
writing an error type into $dport_dev/einj_inject will inject said error
type into the CXL dport represented by $dport_dev.

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
Documentation/ABI/testing/debugfs-cxl | 30 ++++++++++++++++++++
drivers/cxl/Kconfig | 1 +
drivers/cxl/core/port.c | 41 +++++++++++++++++++++++++++
3 files changed, 72 insertions(+)

diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl
index fe61d372e3fa..4c0f62f881ca 100644
--- a/Documentation/ABI/testing/debugfs-cxl
+++ b/Documentation/ABI/testing/debugfs-cxl
@@ -33,3 +33,33 @@ Description:
device cannot clear poison from the address, -ENXIO is returned.
The clear_poison attribute is only visible for devices
supporting the capability.
+
+What: /sys/kernel/debug/cxl/einj_types
+Date: January, 2024
+KernelVersion: v6.9
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Prints the CXL protocol error types made available by
+ the platform in the format "0x<error number> <error type>".
+ The possible error types are (as of ACPI v6.5):
+ 0x1000 CXL.cache Protocol Correctable
+ 0x2000 CXL.cache Protocol Uncorrectable non-fatal
+ 0x4000 CXL.cache Protocol Uncorrectable fatal
+ 0x8000 CXL.mem Protocol Correctable
+ 0x10000 CXL.mem Protocol Uncorrectable non-fatal
+ 0x20000 CXL.mem Protocol Uncorrectable fatal
+
+ The <error number> can be written to einj_inject to inject
+ <error type> into a chosen dport.
+
+What: /sys/kernel/debug/cxl/$dport_dev/einj_inject
+Date: January, 2024
+KernelVersion: v6.9
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (WO) Writing an integer to this file injects the corresponding
+ CXL protocol error into $dport_dev ($dport_dev will be a device
+ name from /sys/bus/pci/devices). The integer to type mapping for
+ injection can be found by reading from einj_types. If the dport
+ was enumerated in RCH mode, a CXL 1.1 error is injected, otherwise
+ a CXL 2.0 error is injected.
diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index 67998dbd1d46..c86ae4c65c03 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -2,6 +2,7 @@
menuconfig CXL_BUS
tristate "CXL (Compute Express Link) Devices Support"
depends on PCI
+ depends on ACPI_APEI_EINJ_CXL || !ACPI_APEI_EINJ_CXL
select FW_LOADER
select FW_UPLOAD
select PCI_DOE
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index e59d9d37aa65..3b579eef4d23 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -3,6 +3,7 @@
#include <linux/platform_device.h>
#include <linux/memregion.h>
#include <linux/workqueue.h>
+#include <linux/einj-cxl.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/module.h>
@@ -793,6 +794,39 @@ static int cxl_dport_setup_regs(struct device *host, struct cxl_dport *dport,
return rc;
}

+DEFINE_SHOW_ATTRIBUTE(einj_cxl_available_error_type);
+
+static int cxl_einj_inject(void *data, u64 type)
+{
+ struct cxl_dport *dport = data;
+
+ if (dport->rch)
+ return einj_cxl_inject_rch_error(dport->rcrb.base, type);
+
+ return einj_cxl_inject_error(to_pci_dev(dport->dport_dev), type);
+}
+DEFINE_DEBUGFS_ATTRIBUTE(cxl_einj_inject_fops, NULL, cxl_einj_inject, "%llx\n");
+
+static void cxl_debugfs_create_dport_dir(struct cxl_dport *dport)
+{
+ struct dentry *dir;
+
+ if (!einj_cxl_is_initialized())
+ return;
+
+ /*
+ * dport_dev needs to be a PCIe port for CXL 2.0+ ports because
+ * EINJ expects a dport SBDF to be specified for 2.0 error injection.
+ */
+ if (!dport->rch && !dev_is_pci(dport->dport_dev))
+ return;
+
+ dir = cxl_debugfs_create_dir(dev_name(dport->dport_dev));
+
+ debugfs_create_file("einj_inject", 0200, dir, dport,
+ &cxl_einj_inject_fops);
+}
+
static struct cxl_port *__devm_cxl_add_port(struct device *host,
struct device *uport_dev,
resource_size_t component_reg_phys,
@@ -1149,6 +1183,8 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
if (dev_is_pci(dport_dev))
dport->link_latency = cxl_pci_get_latency(to_pci_dev(dport_dev));

+ cxl_debugfs_create_dport_dir(dport);
+
return dport;
}

@@ -2221,6 +2257,11 @@ static __init int cxl_core_init(void)

cxl_debugfs = debugfs_create_dir("cxl", NULL);

+ if (einj_cxl_is_initialized()) {
+ debugfs_create_file("einj_types", 0400, cxl_debugfs, NULL,
+ &einj_cxl_available_error_type_fops);
+ }
+
cxl_mbox_init();

rc = cxl_memdev_init();
--
2.34.1