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Message-ID: <ea1af897-b05f-4f83-98ad-dc81e473d3fa@intel.com>
Date: Tue, 3 Feb 2026 11:49:02 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: "Bowman, Terry" <terry.bowman@....com>, dave@...olabs.net,
jonathan.cameron@...wei.com, alison.schofield@...el.com,
dan.j.williams@...el.com, bhelgaas@...gle.com, shiju.jose@...wei.com,
ming.li@...omail.com, Smita.KoralahalliChannabasappa@....com,
rrichter@....com, dan.carpenter@...aro.org,
PradeepVineshReddy.Kodamati@....com, lukas@...ner.de,
Benjamin.Cheatham@....com, sathyanarayanan.kuppuswamy@...ux.intel.com,
linux-cxl@...r.kernel.org, vishal.l.verma@...el.com, alucerop@....com,
ira.weiny@...el.com
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v15 7/9] cxl: Update Endpoint AER uncorrectable handler
On 2/3/26 11:35 AM, Bowman, Terry wrote:
> On 2/3/2026 11:31 AM, Dave Jiang wrote:
>>
>>
>> On 2/2/26 7:52 PM, Terry Bowman wrote:
>>> CXL drivers now implement protocol RAS support. PCI protocol errors,
>>> however, continue to be reported via the AER capability and must still be
>>> handled by a PCI error recovery callback.
>>>
>>> Replace the existing cxl_error_detected() callback in cxl/pci.c with a
>>> new cxl_pci_error_detected() implementation that handles only uncorrectable
>>> PCI protocol errors reported through AER.
>>
>> Do we need to explain why only uncorrectable is handled?
>>
>
> Would it be Ok if I removed "only" with s/only// ?
>
> After mentioning an important detail I shoud elaborate. But, how about if
> remove it and not refer to the CE at all here? CE shouldnt be mentioned unless
> good reason in a primarily UCE patch.
Is CE handling added later? Maybe just say that.
DJ
>
> - Terry
>
>>>
>>> Introduce helper named cxl_handler_aer() amd implement to handle and
>>> log the CXL device's AER error.
>>>
>>> This cleanly separates CXL protocol error handling from PCI AER handling
>>> and ensures that each subsystem processes only the errors it is
>>> responsible.
>>>
>>> Signed-off-by: Terry Bowman <terry.bowman@....com>
>>>
>>> ---
>>>
>>> Changes in v14->v15:
>>> - Title update (Terry)
>>> - Change cxl_pci_error-detected() to handle & log AER (Terry)
>>> - Update commit message (Terry)
>>> - Moved cxl_handle_ras()/cxl_handle_cor_ras() to earlier patch (Terry)
>>>
>>> Changes in v13->v14:
>>> - Update commit headline (Bjorn)
>>> - Rename pci_error_detected()/pci_cor_error_detected() ->
>>> cxl_pci_error_detected/cxl_pci_cor_error_detected() (Jonathan)
>>> - Remove now-invalid comment in cxl_error_detected() (Jonathan)
>>> - Split into separate patches for UCE and CE (Terry)
>>>
>>> Changes in v12->v13:
>>> - Update commit messaqge (Terry)
>>> - Updated all the implementation and commit message. (Terry)
>>> - Refactored cxl_cor_error_detected()/cxl_error_detected() to remove
>>> pdev (Dave Jiang)
>>>
>>> Changes in v11->v12:
>>> - None
>>>
>>> Changes in v10->v11:
>>> - cxl_error_detected() - Change handlers' scoped_guard() to guard() (Jonathan)
>>> - cxl_error_detected() - Remove extra line (Shiju)
>>> - Changes moved to core/ras.c (Terry)
>>> - cxl_error_detected(), remove 'ue' and return with function call. (Jonathan)
>>> - Remove extra space in documentation for PCI_ERS_RESULT_PANIC definition
>>> - Move #include "pci.h from cxl.h to core.h (Terry)
>>> - Remove unnecessary includes of cxl.h and core.h in mem.c (Terry)
>>> ---
>>> drivers/cxl/core/ras.c | 68 +++++++++++++++---------------------------
>>> drivers/cxl/cxlpci.h | 9 +++---
>>> drivers/cxl/pci.c | 6 ++--
>>> 3 files changed, 31 insertions(+), 52 deletions(-)
>>>
>>> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
>>> index 970ff3df442c..061e6aaec176 100644
>>> --- a/drivers/cxl/core/ras.c
>>> +++ b/drivers/cxl/core/ras.c
>>> @@ -441,55 +441,35 @@ void cxl_cor_error_detected(struct pci_dev *pdev)
>>> }
>>> EXPORT_SYMBOL_NS_GPL(cxl_cor_error_detected, "CXL");
>>>
>>> -pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>>> - pci_channel_state_t state)
>>> +static bool cxl_handle_aer(struct pci_dev *pdev)
>>
>> For a function that returns a bool, the function name doesn't sound quite right. Maybe cxl_uncor_aer_present()?
>>
>> DJ
>>
>
> I was trying to follow the pattern of detected() function calls the
> handle() function as done for cxl_handle_ras() and cxl_handle_cor_ras().
>
> I will change to cxl_uncor_aer_present().
>
> -Terry
>
>>> {
>>> - struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
>>> - struct cxl_memdev *cxlmd = cxlds->cxlmd;
>>> - struct device *dev = &cxlmd->dev;
>>> - bool ue;
>>> -
>>> - scoped_guard(device, dev) {
>>> - if (!dev->driver) {
>>> - dev_warn(&pdev->dev,
>>> - "%s: memdev disabled, abort error handling\n",
>>> - dev_name(dev));
>>> - return PCI_ERS_RESULT_DISCONNECT;
>>> - }
>>> + struct aer_capability_regs aer;
>>> + u32 aer_cap = pdev->aer_cap;
>>>
>>> - if (cxlds->rcd)
>>> - cxl_handle_rdport_errors(cxlds);
>>> - /*
>>> - * 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_handle_ras(&cxlds->cxlmd->dev, cxlds->serial,
>>> - cxlmd->endpoint->regs.ras);
>>> + if (!aer_cap) {
>>> + pr_warn_ratelimited("%s: AER capability isn't present\n",
>>> + pci_name(pdev));
>>> + return false;
>>> }
>>>
>>> - 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;
>>> + pci_read_config_dword(pdev, aer_cap + PCI_ERR_UNCOR_STATUS, &aer.uncor_status);
>>> + pci_read_config_dword(pdev, aer_cap + PCI_ERR_UNCOR_MASK, &aer.uncor_mask);
>>> +
>>> + /* The AER driver logged the error */
>>> + pci_aer_clear_nonfatal_status(pdev);
>>> + pci_aer_clear_fatal_status(pdev);
>>> +
>>> + return (aer.uncor_status & aer.uncor_mask);
>>> +}
>>> +
>>> +pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>>> + pci_channel_state_t error)
>>> +{
>>> + u32 rc = cxl_handle_aer(pdev);
>>> +
>>> + return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_CAN_RECOVER;
>>> }
>>> -EXPORT_SYMBOL_NS_GPL(cxl_error_detected, "CXL");
>>> +EXPORT_SYMBOL_NS_GPL(cxl_pci_error_detected, "CXL");
>>>
>>> static void cxl_handle_proto_error(struct cxl_proto_err_work_data *err_info)
>>> {
>>> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
>>> index 970add0256e9..5534422b496c 100644
>>> --- a/drivers/cxl/cxlpci.h
>>> +++ b/drivers/cxl/cxlpci.h
>>> @@ -79,15 +79,14 @@ void read_cdat_data(struct cxl_port *port);
>>>
>>> #ifdef CONFIG_CXL_RAS
>>> void cxl_cor_error_detected(struct pci_dev *pdev);
>>> -pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>>> - pci_channel_state_t state);
>>> void devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport);
>>> +pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>>> + pci_channel_state_t error);
>>> void devm_cxl_port_ras_setup(struct cxl_port *port);
>>> #else
>>> static inline void cxl_cor_error_detected(struct pci_dev *pdev) { }
>>> -
>>> -static inline pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>>> - pci_channel_state_t state)
>>> +static inline pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>>> + pci_channel_state_t state)
>>> {
>>> return PCI_ERS_RESULT_NONE;
>>> }
>>> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
>>> index acb0eb2a13c3..ff741adc7c7f 100644
>>> --- a/drivers/cxl/pci.c
>>> +++ b/drivers/cxl/pci.c
>>> @@ -1051,8 +1051,8 @@ static void cxl_reset_done(struct pci_dev *pdev)
>>> }
>>> }
>>>
>>> -static const struct pci_error_handlers cxl_error_handlers = {
>>> - .error_detected = cxl_error_detected,
>>> +static const struct pci_error_handlers pci_error_handlers = {
>>> + .error_detected = cxl_pci_error_detected,
>>> .slot_reset = cxl_slot_reset,
>>> .resume = cxl_error_resume,
>>> .cor_error_detected = cxl_cor_error_detected,
>>> @@ -1063,7 +1063,7 @@ 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,
>>> + .err_handler = &pci_error_handlers,
>>> .dev_groups = cxl_rcd_groups,
>>> .driver = {
>>> .probe_type = PROBE_PREFER_ASYNCHRONOUS,
>>
>
>
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