From: Dan Williams <dan.j.williams@xxxxxxxxx>
Add nominal error handling that tears down CXL.mem in response to error
notifications that imply a device reset. Given some CXL.mem may be
operating as System RAM, there is a high likelihood that these error
events are fatal. However, if the system survives the notification the
expectation is that the driver behavior is equivalent to a hot-unplug
and re-plug of an endpoint.
Note that this does not change the mask values from the default. That
awaits CXL _OSC support to determine whether platform firmware is in
control of the mask registers.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
drivers/cxl/core/memdev.c | 1
drivers/cxl/cxl.h | 1
drivers/cxl/cxlmem.h | 2 +
drivers/cxl/pci.c | 136 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 140 insertions(+)
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 20ce488a7754..a74a93310d26 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -344,6 +344,7 @@ struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds)
* needed as this is ordered with cdev_add() publishing the device.
*/
cxlmd->cxlds = cxlds;
+ cxlds->cxlmd = cxlmd;
cdev = &cxlmd->cdev;
rc = cdev_device_add(cdev, dev);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index d453aeb92cb0..ff203073c8a2 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -136,6 +136,7 @@ static inline int ways_to_cxl(unsigned int ways, u8 *iw)
#define CXL_RAS_CORRECTABLE_MASK_OFFSET 0x10
#define CXL_RAS_CORRECTABLE_MASK_MASK GENMASK(6, 0)
#define CXL_RAS_CAP_CONTROL_OFFSET 0x14
+#define CXL_RAS_CAP_CONTROL_FE_MASK GENMASK(5, 0)
#define CXL_RAS_HEADER_LOG_OFFSET 0x18
#define CXL_RAS_CAPABILITY_LENGTH 0x58
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 88e3a8e54b6a..b3117fd67f42 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -186,6 +186,7 @@ struct cxl_endpoint_dvsec_info {
* Currently only memory devices are represented.
*
* @dev: The device associated with this CXL state
+ * @cxlmd: The device representing the CXL.mem capabilities of @dev
* @regs: Parsed register blocks
* @cxl_dvsec: Offset to the PCIe device DVSEC
* @payload_size: Size of space for payload
@@ -218,6 +219,7 @@ struct cxl_endpoint_dvsec_info {
*/
struct cxl_dev_state {
struct device *dev;
+ struct cxl_memdev *cxlmd;
struct cxl_regs regs;
int cxl_dvsec;
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 0f36a5861a7b..dad69110291d 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -9,6 +9,7 @@
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/pci-doe.h>
+#include <linux/aer.h>
#include <linux/io.h>
#include "cxlmem.h"
#include "cxlpci.h"
@@ -404,6 +405,11 @@ static void devm_cxl_pci_create_doe(struct cxl_dev_state *cxlds)
}
}
+static void disable_aer(void *pdev)
+{
+ pci_disable_pcie_error_reporting(pdev);
+}
+
static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct cxl_register_map map;
@@ -425,6 +431,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
cxlds = cxl_dev_state_create(&pdev->dev);
if (IS_ERR(cxlds))
return PTR_ERR(cxlds);
+ pci_set_drvdata(pdev, cxlds);
cxlds->serial = pci_get_dsn(pdev);
cxlds->cxl_dvsec = pci_find_dvsec_capability(
@@ -479,6 +486,14 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
if (IS_ERR(cxlmd))
return PTR_ERR(cxlmd);
+ if (cxlds->regs.ras) {
+ pci_enable_pcie_error_reporting(pdev);
+ rc = devm_add_action_or_reset(&pdev->dev, disable_aer, pdev);
+ if (rc)
+ return rc;
+ }
+ pci_save_state(pdev);
+
if (resource_size(&cxlds->pmem_res) && IS_ENABLED(CONFIG_CXL_PMEM))
rc = devm_cxl_add_nvdimm(&pdev->dev, cxlmd);
@@ -492,10 +507,131 @@ static const struct pci_device_id cxl_mem_pci_tbl[] = {
};
MODULE_DEVICE_TABLE(pci, cxl_mem_pci_tbl);
+/* CXL spec rev3.0 8.2.4.16.1 */
+static void header_log_copy(struct cxl_dev_state *cxlds, u32 *log)
+{
+ void __iomem *addr;
+ u32 *log_addr;
+ int i, log_u32_size = CXL_HEADERLOG_SIZE / sizeof(u32);
+
+ addr = cxlds->regs.ras + CXL_RAS_HEADER_LOG_OFFSET;
+ log_addr = log;
+
+ for (i = 0; i < log_u32_size; i++) {
+ *log_addr = readl(addr);
+ log_addr++;
+ addr += sizeof(u32);
+ }
+}
+
+/*
+ * Log the state of the RAS status registers and prepare them to log the
+ * next error status. Return 1 if reset needed.
+ */
+static bool cxl_report_and_clear(struct cxl_dev_state *cxlds)
+{
+ struct cxl_memdev *cxlmd = cxlds->cxlmd;
+ struct device *dev = &cxlmd->dev;
+ u32 hl[CXL_HEADERLOG_SIZE_U32];
+ void __iomem *addr;
+ u32 status;
+ u32 fe;
+
+ if (!cxlds->regs.ras)
+ return false;
+
+ addr = cxlds->regs.ras + CXL_RAS_UNCORRECTABLE_STATUS_OFFSET;
+ status = le32_to_cpu(readl(addr));
+ if (!(status & CXL_RAS_UNCORRECTABLE_STATUS_MASK))
+ return false;
+
+ /* If multiple errors, log header points to first error from ctrl reg */
+ if (hweight32(status) > 1) {
+ addr = cxlds->regs.ras + CXL_RAS_CAP_CONTROL_OFFSET;
+ fe = BIT(le32_to_cpu(readl(addr)) & CXL_RAS_CAP_CONTROL_FE_MASK);
+ } else {
+ fe = status;
+ }
+
+ header_log_copy(cxlds, hl);
+ trace_cxl_aer_uncorrectable_error(dev_name(dev), status, fe, hl);
+ writel(status & CXL_RAS_UNCORRECTABLE_STATUS_MASK, addr);
+
+ return true;
+}
+
+static pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
+ pci_channel_state_t state)
+{
+ struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
+ struct cxl_memdev *cxlmd = cxlds->cxlmd;
+ struct device *dev = &cxlmd->dev;
+ bool ue;
+
+ /*
+ * A frozen channel indicates an impending reset which is fatal to
+ * CXL.mem operation, and will likely crash the system. On the off
+ * chance the situation is recoverable dump the status of the RAS
+ * capability registers and bounce the active state of the memdev.
+ */
+ ue = cxl_report_and_clear(cxlds);
+
+ switch (state) {
+ case pci_channel_io_normal:
+ if (ue) {
+ device_release_driver(dev);
+ return PCI_ERS_RESULT_NEED_RESET;
+ }
+ return PCI_ERS_RESULT_CAN_RECOVER;
+ case pci_channel_io_frozen:
+ dev_warn(&pdev->dev,
+ "%s: frozen state error detected, disable CXL.mem\n",
+ dev_name(dev));
+ device_release_driver(dev);
+ return PCI_ERS_RESULT_NEED_RESET;
+ case pci_channel_io_perm_failure:
+ dev_warn(&pdev->dev,
+ "failure state error detected, request disconnect\n");
+ return PCI_ERS_RESULT_DISCONNECT;
+ }
+ return PCI_ERS_RESULT_NEED_RESET;
+}
+
+static pci_ers_result_t cxl_slot_reset(struct pci_dev *pdev)
+{
+ struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
+ struct cxl_memdev *cxlmd = cxlds->cxlmd;
+ struct device *dev = &cxlmd->dev;
+
+ dev_info(&pdev->dev, "%s: restart CXL.mem after slot reset\n",
+ dev_name(dev));
+ pci_restore_state(pdev);
+ if (device_attach(dev) <= 0)
+ return PCI_ERS_RESULT_DISCONNECT;
+ return PCI_ERS_RESULT_RECOVERED;
+}
+
+static void cxl_error_resume(struct pci_dev *pdev)
+{
+ struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
+ struct cxl_memdev *cxlmd = cxlds->cxlmd;
+ struct device *dev = &cxlmd->dev;
+
+ dev_info(&pdev->dev, "%s: error resume %s\n", dev_name(dev),
+ dev->driver ? "successful" : "failed");
+}
+
+static const struct pci_error_handlers cxl_error_handlers = {
+ .error_detected = cxl_error_detected,
+ .slot_reset = cxl_slot_reset,
+ .resume = cxl_error_resume,
+};
+
static struct pci_driver cxl_pci_driver = {
.name = KBUILD_MODNAME,
.id_table = cxl_mem_pci_tbl,
.probe = cxl_pci_probe,
+ .err_handler = &cxl_error_handlers,
.driver = {
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
