From 2905cb5236cba63a5dc8a83752dcc31f3cc819f9 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 29 Nov 2022 10:48:59 -0700 Subject: [PATCH] cxl/pci: Add (hopeful) error handling support 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. Reviewed-by: Jonathan Cameron Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/166974413966.1608150.15522782911404473932.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Dan Williams --- drivers/cxl/core/memdev.c | 1 + drivers/cxl/cxl.h | 1 + drivers/cxl/cxlmem.h | 2 + drivers/cxl/pci.c | 137 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 141 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 e533c5b5e4b0..2f3951b76e2d 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -132,6 +132,7 @@ 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 8b817138140a..a7c2d733e5ae 100644 --- a/drivers/cxl/pci.c +++ b/drivers/cxl/pci.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include "cxlmem.h" #include "cxlpci.h" @@ -399,6 +400,11 @@ 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; @@ -420,6 +426,7 @@ 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( @@ -474,6 +481,14 @@ 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); @@ -487,10 +502,132 @@ 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((__force __le32)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((__force __le32)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, },