On 7/20/2026 12:38 PM, Dave Jiang wrote:
>
>
> On 7/17/26 3:57 PM, Terry Bowman wrote:
>> This patch is intended to provide a method of testing the recently submitted
>> cxl series "cxl: Enable CXL PCIe Port Protocol Error handling and logging"
>> found
>> here:
>>
>> https://lore.kernel.org/linux-cxl/[email protected]/T/#md90ec1fdd1b374bf1e32e7736e2b3e34b328c701
>>
>> The changes in this patch will allow CXL RAS protocol testing by injecting
>> AER errors using AER EINJ. The RAS register block status is updated
>> using a central function to augment RAS register block returned by
>> to_ras_base(). This supports all CXL devices including Root Ports,
>> Upstream Switch Ports, Downstream Switch Ports, Endpoints, and RCH
>> Downstream Ports.
>>
>> Add debugfs-based CXL protocol error injection for testing CXL RAS
>> error handling paths. Injects CXL RAS protocol errors using AER internal
>> error inject interface via /sys/kernel/debug/cxl/aer_einj_inject.
>>
>> RAS CXL status is set using to_ras_base() function override when kernel
>> config
>> CONFIG_CXL_PROTO_AER_EINJ is enabled.
>>
>> Usage:
>> echo "DDDD:BB:DD.F [UCE|CE] AER_STATUS RAS_STATUS [RCH]" > \
>> /sys/kernel/debug/cxl/aer_einj_inject
>>
>> Move struct aer_error_inj and aer_inject() to linux/aer.h so CXL
>> can invoke AER injection directly. Export aer_inject() with
>> EXPORT_SYMBOL_GPL.
>>
>> Make cxl_debugfs non-static in port.c and declare it extern in
>> core.h so the debugfs file can be created under the existing CXL
>> debugfs root.
>>
>> Co-developed-by: Ben Cheatham <[email protected]>
>> Signed-off-by: Ben Cheatham <[email protected]>
>> Signed-off-by: Terry Bowman <[email protected]>
>> ---
>> drivers/cxl/Kconfig | 13 +++
>> drivers/cxl/core/core.h | 21 ++++
>> drivers/cxl/core/port.c | 2 +-
>> drivers/cxl/core/ras.c | 208 ++++++++++++++++++++++++++++++++++
>> drivers/cxl/core/ras_rch.c | 12 ++
>> drivers/pci/pcie/aer_inject.c | 29 ++---
>> include/linux/aer.h | 15 +++
>> 7 files changed, 281 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
>> index 80aeb0d556bd7..ef449228b2549 100644
>> --- a/drivers/cxl/Kconfig
>> +++ b/drivers/cxl/Kconfig
>> @@ -238,6 +238,19 @@ config CXL_RAS
>> def_bool y
>> depends on ACPI_APEI_GHES && PCIEAER && CXL_BUS
>>
>> +config CXL_PROTO_AER_EINJ
>> + bool "CXL: RAS Protocol Error Injection using AER EINJ"
>> + depends on CXL_RAS
>> + depends on PCIEAER_INJECT
>> + help
>> + Enable debugfs-based CXL protocol error injection. Writes to
>> + /sys/kernel/debug/cxl/aer_einj_inject inject CXL RAS protocol
>> + errors using the AER internal error inject interface.
>> +
>> + This is a debug/test facility. Say N for production kernels.
>> +
>> + If unsure say N.
>> +
>> config CXL_ATL
>> def_bool y
>> depends on CXL_REGION
>> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
>> index a55a4e409feda..91910d2bb5d39 100644
>> --- a/drivers/cxl/core/core.h
>> +++ b/drivers/cxl/core/core.h
>> @@ -182,6 +182,9 @@ static inline struct device *dport_to_host(struct
>> cxl_dport *dport)
>> return port->uport_dev;
>> return &port->dev;
>> }
>> +
>> +extern struct dentry *cxl_debugfs;
>> +
>> #ifdef CONFIG_CXL_RAS
>> void cxl_ras_init(void);
>> void cxl_ras_exit(void);
>> @@ -244,4 +247,22 @@ int cxl_set_feature(struct cxl_mailbox *cxl_mbox, const
>> uuid_t *feat_uuid,
>>
>> resource_size_t cxl_rcd_component_reg_phys(struct device *dev,
>> struct cxl_dport *dport);
>> +
>> +#ifdef CONFIG_CXL_PROTO_AER_EINJ
>> +
>> +#define AER_REGISTER_SIZE 5
>> +#define RAS_REGISTER_SIZE (CXL_RAS_CAPABILITY_LENGTH / sizeof(u32))
>> +
>> +struct cxl_aer_einj {
>> + int correctable;
>> + bool is_rch;
>> + struct mutex *lock;
>> + struct device *dev;
>> + u32 aer_registers[AER_REGISTER_SIZE];
>> + u32 ras_registers[RAS_REGISTER_SIZE];
>> +};
>> +
>> +extern struct cxl_aer_einj cxl_aer_einj;
>> +#endif
>> +
>> #endif /* __CXL_CORE_H__ */
>> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
>> index a76f3ee05cba8..79657e5fddaac 100644
>> --- a/drivers/cxl/core/port.c
>> +++ b/drivers/cxl/core/port.c
>> @@ -2501,7 +2501,7 @@ const struct bus_type cxl_bus_type = {
>> };
>> EXPORT_SYMBOL_NS_GPL(cxl_bus_type, "CXL");
>>
>> -static struct dentry *cxl_debugfs;
>> +struct dentry *cxl_debugfs;
>>
>> struct dentry *cxl_debugfs_create_dir(const char *dir)
>> {
>> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
>> index d77208af41e03..d41deea899d30 100644
>> --- a/drivers/cxl/core/ras.c
>> +++ b/drivers/cxl/core/ras.c
>> @@ -3,6 +3,7 @@
>>
>> #include <linux/pci.h>
>> #include <linux/aer.h>
>> +#include <linux/debugfs.h>
>> #include <cxl/event.h>
>> #include <cxlmem.h>
>> #include <cxlpci.h>
>> @@ -117,6 +118,195 @@ static void cxl_cper_prot_err_work_fn(struct
>> work_struct *work)
>> }
>> static DECLARE_WORK(cxl_cper_prot_err_work, cxl_cper_prot_err_work_fn);
>>
>> +#if IS_ENABLED(CONFIG_CXL_PROTO_AER_EINJ)
>
> Can this be moved to a header file? Prefer to not introduce #ifdef in the C
> source.
>
Yes, I will move to core.h.
>> +
>> +static DEFINE_MUTEX(cxl_aer_einj_mutex);
>> +
>> +struct cxl_aer_einj cxl_aer_einj = {
>> + .lock = &cxl_aer_einj_mutex,
>> +};
>> +
>> +static const char cxl_aer_einj_usage[] =
>> + "ssss:bb:dd.f [UCE|CE] AER_STATUS RAS_STATUS [RCH]\n";
>> +
>> +static int cxl_aer_inject_error(struct pci_dev *pdev, bool correctable,
>> + u32 aer_status, u32 ras_status)
>> +{
>> + /* RCD errors are signaled as internal errors on the associated RCEC */
>> + if (pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_END) {
>> + if (!pdev->rcec)
>> + return -ENODEV;
>> + pdev = pdev->rcec;
>> + }
>> +
>> + struct aer_error_inj einj = {
>> + .bus = pdev->bus->number,
>> + .dev = PCI_SLOT(pdev->devfn),
>> + .fn = PCI_FUNC(pdev->devfn),
>> + .domain = pci_domain_nr(pdev->bus),
>> + };
>> + int ret;
>> + int aer_offset;
>> + int ras_offset;
>> +
>> + if (correctable) {
>> + einj.cor_status = aer_status | PCI_ERR_COR_INTERNAL;
>> + aer_offset = PCI_ERR_COR_STATUS / sizeof(u32);
>> + ras_offset = CXL_RAS_CORRECTABLE_STATUS_OFFSET / sizeof(u32);
>> + } else {
>> + einj.uncor_status = aer_status | PCI_ERR_UNC_INTN;
>> + aer_offset = PCI_ERR_UNCOR_STATUS / sizeof(u32);
>> + ras_offset = CXL_RAS_UNCORRECTABLE_STATUS_OFFSET / sizeof(u32);
>> + }
>> +
>> + cxl_aer_einj.correctable = correctable;
>> + cxl_aer_einj.aer_registers[aer_offset] = aer_status;
>> + cxl_aer_einj.ras_registers[ras_offset] = ras_status;
>> +
>> + ret = aer_inject(&einj);
>> + if (ret) {
>> + pr_err("cxl-einj: aer_inject failed: %d\n", ret);
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static ssize_t cxl_aer_einj_write(struct file *file,
>> + const char __user *ubuf,
>> + size_t count, loff_t *ppos)
>> +{
>> + char sbdf[16], severity[4], topology[4] = "";
>> + unsigned int domain, bus, dev, fn;
>> + u32 aer_status, ras_status;
>> + struct cxl_dport *dport;
>> + char buf[128];
>> + int nargs;
>> + int ret;
>> +
>> + if (!capable(CAP_SYS_ADMIN))
>> + return -EPERM;
>> +
>> + if (count >= sizeof(buf)) {
>> + pr_err("cxl-einj: input too long (%zu bytes, max %zu)\n",
>> count, sizeof(buf) - 1);
>> + return -EINVAL;
>> + }
>> +
>> + if (copy_from_user(buf, ubuf, count)) {
>> + pr_err("cxl-einj: copy_from_user failed\n");
>> + return -EFAULT;
>> + }
>> + buf[count] = '\0';
>> +
>> + nargs = sscanf(buf, "%15s %3s %x %x %3s", sbdf, severity,
>> + &aer_status, &ras_status, topology);
>> + if (nargs < 4) {
>> + pr_err("cxl-einj: expected format: <SBDF> <UCE|CE> <aer_status>
>> <ras_status>\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (nargs == 5 && strcmp(topology, "RCH") != 0)
>> + return -EINVAL;
>> +
>> + if (strcmp(severity, "UCE") != 0 && strcmp(severity, "CE") != 0) {
>> + pr_err("cxl-einj: expected 'UCE' or 'CE', got '%s'\n",
>> severity);
>> + return -EINVAL;
>> + }
>> +
>> + if (sscanf(sbdf, "%x:%x:%x.%x", &domain, &bus, &dev, &fn) != 4) {
>> + pr_err("cxl-einj: invalid SBDF format '%s', expected
>> DDDD:BB:DD.F\n", sbdf);
>> + return -EINVAL;
>> + }
>> +
>> + struct pci_dev *pdev __free(pci_dev_put) =
>> + pci_get_domain_bus_and_slot(domain, bus, PCI_DEVFN(dev, fn));
>> + if (!pdev) {
>> + pr_err("cxl-einj: device %s not found\n", sbdf);
>> + return -ENODEV;
>> + }
>> +
>> + guard(mutex)(cxl_aer_einj.lock);
>> + cxl_aer_einj.dev = NULL;
>> +
>> + struct cxl_port *port __free(put_cxl_port) =
>> find_cxl_port_by_dev(&pdev->dev, &dport);
>> + if (!port) {
>> + dev_err(&pdev->dev, "cxl-einj: Failed to find CXL Port.\n");
>> + return -ENODEV;
>> + }
>> +
>> + if (!to_ras_base(port, dport)) {
>> + dev_err(&pdev->dev, "cxl-einj: RAS not initialized.\n");
>> + return -ENODEV;
>> + }
>> +
>> + cxl_aer_einj.is_rch = (nargs == 5 && strcmp(topology, "RCH") == 0);
>> + if (!cxl_aer_einj.is_rch)
>> + pci_dev_get(pdev);
>> + cxl_aer_einj.dev = cxl_aer_einj.is_rch ? pdev->dev.parent : &pdev->dev;
>> + ret = cxl_aer_inject_error(pdev, strcmp(severity, "CE") == 0,
>> + aer_status, ras_status);
>> + if (ret) {
>> + if (!cxl_aer_einj.is_rch)
>> + pci_dev_put(pdev);
>> + cxl_aer_einj.dev = NULL;
>> + pr_err("cxl-einj: injection failed for %s: %d\n", sbdf, ret);
>> + return ret;
>> + }
>> +
>> + return count;
>> +}
>> +
>> +static ssize_t cxl_aer_einj_read(struct file *file, char __user *ubuf,
>> + size_t count, loff_t *ppos)
>> +{
>> + return simple_read_from_buffer(ubuf, count, ppos,
>> + cxl_aer_einj_usage,
>> + sizeof(cxl_aer_einj_usage) - 1);
>> +}
>> +
>> +static const struct file_operations cxl_ras_error_fops = {
>> + .owner = THIS_MODULE,
>> + .read = cxl_aer_einj_read,
>> + .write = cxl_aer_einj_write,
>> + .llseek = default_llseek,
>> +};
>> +
>> +static void cxl_ras_create_debugfs(struct dentry *dir)
>> +{
>> + debugfs_create_file("aer_einj_inject", 0600, dir, NULL,
>> + &cxl_ras_error_fops);
>> +}
>> +
>> +static void __iomem *to_einj_ras_base(struct cxl_port *port, struct
>> cxl_dport *dport)
>> +{
>> + if (dport) {
>> + if (cxl_aer_einj.is_rch) {
>> + if (cxl_aer_einj.dev == dport->dport_dev) {
>> + cxl_aer_einj.dev = NULL;
>> + return (__force void __iomem
>> *)cxl_aer_einj.ras_registers;
>> + }
>> + } else {
>> + if (cxl_aer_einj.dev == dport->dport_dev) {
>> + pci_dev_put(to_pci_dev(cxl_aer_einj.dev));
>> + cxl_aer_einj.dev = NULL;
>> + return (__force void __iomem
>> *)cxl_aer_einj.ras_registers;
>> + }
>> + }
>> + } else if (!cxl_aer_einj.is_rch) {
>> + struct device *dev = is_cxl_endpoint(port) ?
>> + port->uport_dev->parent : port->uport_dev;
>> +
>> + if (dev_is_pci(dev) && cxl_aer_einj.dev == dev) {
>> + pci_dev_put(to_pci_dev(cxl_aer_einj.dev));
>> + cxl_aer_einj.dev = NULL;
>> + return (__force void __iomem
>> *)cxl_aer_einj.ras_registers;
>> + }
>> + }
>> +
>> + return NULL;
>> +}
>> +#endif
>> +
>> static void cxl_unmask_proto_interrupts(struct device *dev)
>> {
>> struct pci_dev *pdev;
>> @@ -238,6 +428,14 @@ void __iomem *to_ras_base(struct cxl_port *port, struct
>> cxl_dport *dport)
>> if (!port)
>> return NULL;
>>
>> +#if IS_ENABLED(CONFIG_CXL_PROTO_AER_EINJ)
>
> I think you can do something like below instead:
>
> if (IS_ENABLED(CONFIG_CXL_PROTO_AER_EINJ))
>
> DJ
>
Good idea. Thanks for pointing this out.
Terry
[snip]
