linux-kernel - Re: [PATCH v4] PCI: Prevent power state transition of erroneous device

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Message-ID: <85ed0b91-c84f-4d24-8e19-a8cb3ba02b14@gmail.com>
Date: Mon, 19 May 2025 23:42:31 +0200
From: Denis Benato <benato.denis96@...il.com>
To: Raag Jadav <raag.jadav@...el.com>, rafael@...nel.org,
 mahesh@...ux.ibm.com, oohall@...il.com, bhelgaas@...gle.com
Cc: linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
 linux-kernel@...r.kernel.org, ilpo.jarvinen@...ux.intel.com,
 lukas@...ner.de, aravind.iddamsetty@...ux.intel.com, superm1@...nel.org
Subject: Re: [PATCH v4] PCI: Prevent power state transition of erroneous
 device


On 5/19/25 12:41, Raag Jadav wrote:
> On Mon, May 19, 2025 at 03:58:08PM +0530, Raag Jadav wrote:
>> If error status is set on an AER capable device, most likely either the
>> device recovery is in progress or has already failed. Neither of the
>> cases are well suited for power state transition of the device, since
>> this can lead to unpredictable consequences like resume failure, or in
>> worst case the device is lost because of it. Leave the device in its
>> existing power state to avoid such issues.
>>
>> Signed-off-by: Raag Jadav <raag.jadav@...el.com>
>> ---
>>
>> v2: Synchronize AER handling with PCI PM (Rafael)
>> v3: Move pci_aer_in_progress() to pci_set_low_power_state() (Rafael)
>>     Elaborate "why" (Bjorn)
>> v4: Rely on error status instead of device status
>>     Condense comment (Lukas)
> Since pci_aer_in_progress() is changed I've not included Rafael's tag with
> my understanding of this needing a revisit. If this was a mistake, please
> let me know.
>
> Denis, Mario, does this fix your issue?
>
Hello,

Unfortunately no, I have prepared a dmesg but had to remove the bootup process because it was too long of a few kb: https://pastebin.com/1uBEA1FL

>> More discussion on [1].
>> [1] https://lore.kernel.org/all/CAJZ5v0g-aJXfVH+Uc=9eRPuW08t-6PwzdyMXsC6FZRKYJtY03Q@mail.gmail.com/
>>
>>  drivers/pci/pci.c      |  9 +++++++++
>>  drivers/pci/pcie/aer.c | 13 +++++++++++++
>>  include/linux/aer.h    |  2 ++
>>  3 files changed, 24 insertions(+)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 4d7c9f64ea24..a20018692933 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -9,6 +9,7 @@
>>   */
>>  
>>  #include <linux/acpi.h>
>> +#include <linux/aer.h>
>>  #include <linux/kernel.h>
>>  #include <linux/delay.h>
>>  #include <linux/dmi.h>
>> @@ -1539,6 +1540,14 @@ static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state, bool
>>  	   || (state == PCI_D2 && !dev->d2_support))
>>  		return -EIO;
>>  
>> +	/*
>> +	 * If error status is set on an AER capable device, it is not well
>> +	 * suited for power state transition. Leave it in its existing power
>> +	 * state to avoid issues like unpredictable resume failure.
>> +	 */
>> +	if (pci_aer_in_progress(dev))
>> +		return -EIO;
>> +
>>  	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
>>  	if (PCI_POSSIBLE_ERROR(pmcsr)) {
>>  		pci_err(dev, "Unable to change power state from %s to %s, device inaccessible\n",
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index a1cf8c7ef628..617fbac0d38a 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -237,6 +237,19 @@ int pcie_aer_is_native(struct pci_dev *dev)
>>  }
>>  EXPORT_SYMBOL_NS_GPL(pcie_aer_is_native, "CXL");
>>  
>> +bool pci_aer_in_progress(struct pci_dev *dev)
>> +{
>> +	int aer = dev->aer_cap;
>> +	u32 cor, uncor;
>> +
>> +	if (!pcie_aer_is_native(dev))
>> +		return false;
>> +
>> +	pci_read_config_dword(dev, aer + PCI_ERR_COR_STATUS, &cor);
>> +	pci_read_config_dword(dev, aer + PCI_ERR_UNCOR_STATUS, &uncor);
>> +	return cor || uncor;
>> +}
>> +
>>  static int pci_enable_pcie_error_reporting(struct pci_dev *dev)
>>  {
>>  	int rc;
>> diff --git a/include/linux/aer.h b/include/linux/aer.h
>> index 02940be66324..e6a380bb2e68 100644
>> --- a/include/linux/aer.h
>> +++ b/include/linux/aer.h
>> @@ -56,12 +56,14 @@ struct aer_capability_regs {
>>  #if defined(CONFIG_PCIEAER)
>>  int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
>>  int pcie_aer_is_native(struct pci_dev *dev);
>> +bool pci_aer_in_progress(struct pci_dev *dev);
>>  #else
>>  static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
>>  {
>>  	return -EINVAL;
>>  }
>>  static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
>> +static inline bool pci_aer_in_progress(struct pci_dev *dev) { return false; }
>>  #endif
>>  
>>  void pci_print_aer(struct pci_dev *dev, int aer_severity,
>> -- 
>> 2.34.1
>>