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From: "Sean V Kelley" <sean.v.kelley@intel.com>
To: "Jonathan Cameron" <Jonathan.Cameron@Huawei.com>
Cc: bhelgaas@google.com, rjw@rjwysocki.net, "Zhuo,
	Qiuxu" <qiuxu.zhuo@intel.com>, "Luck, Tony" <tony.luck@intel.com>,
	sathyanarayanan.kuppuswamy@linux.intel.com,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Raj,
	Ashok" <ashok.raj@intel.com>
Subject: Re: [RFC PATCH 5/9] PCI/AER: Apply function level reset to RCiEP on fatal error
Date: Tue, 28 Jul 2020 09:14:11 -0700
Message-ID: <90E63E9B-DCD3-4325-B1FC-FE5C72BA191B@intel.com> (raw)
In-Reply-To: <a79c227f0913438cb5a94dc80a075a7c@intel.com>

On 28 Jul 2020, at 6:27, Zhuo, Qiuxu wrote:

>> From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
>> Sent: Monday, July 27, 2020 7:17 PM
>> To: Kelley, Sean V <sean.v.kelley@intel.com>
>> Cc: bhelgaas@google.com; rjw@rjwysocki.net; ashok.raj@kernel.org; 
>> Luck,
>> Tony <tony.luck@intel.com>;
>> sathyanarayanan.kuppuswamy@linux.intel.com; 
>> linux-pci@vger.kernel.org;
>> linux-kernel@vger.kernel.org; Zhuo, Qiuxu <qiuxu.zhuo@intel.com>
>> Subject: Re: [RFC PATCH 5/9] PCI/AER: Apply function level reset to 
>> RCiEP
>> on fatal error
>>
>> On Fri, 24 Jul 2020 10:22:19 -0700
>> Sean V Kelley <sean.v.kelley@intel.com> wrote:
>>
>>> From: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
>>>
>>> Attempt to do function level reset for an RCiEP associated with an
>>> RCEC device on fatal error.
>>
>> I'd like to understand more on your reasoning for flr here.
>> Is it simply that it is all we can do, or is there some basis in a 
>> spec
>> somewhere?
>>
>
> Yes. Though there isn't the link reset for the RCiEP here, I think we 
> should still be able to reset the RCiEP via FLR on fatal error, if the 
> RCiEP supports FLR.
>
> -Qiuxu
>

Also see PCIe 5.0-1, Sec. 6.6.2 Function Level Reset (FLR)

Implementation of FLR is optional (not required), but is strongly 
recommended. For an example use case consider CXL. Function 0 DVSEC 
instances control for the CXL functionality of the entire CXL device. 
FLR may succeed in recovering from CXL.io domain errors.

Thanks,

Sean

>>>
>>> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
>>> ---
>>>  drivers/pci/pcie/err.c | 31 ++++++++++++++++++++++---------
>>>  1 file changed, 22 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c index
>>> 044df004f20b..9b3ec94bdf1d 100644
>>> --- a/drivers/pci/pcie/err.c
>>> +++ b/drivers/pci/pcie/err.c
>>> @@ -170,6 +170,17 @@ static void pci_walk_dev_affected(struct
>> pci_dev *dev, int (*cb)(struct pci_dev
>>>  }
>>>  }
>>>
>>> +static enum pci_channel_state flr_on_rciep(struct pci_dev *dev) {
>>> +if (!pcie_has_flr(dev))
>>> +return PCI_ERS_RESULT_NONE;
>>> +
>>> +if (pcie_flr(dev))
>>> +return PCI_ERS_RESULT_DISCONNECT;
>>> +
>>> +return PCI_ERS_RESULT_RECOVERED;
>>> +}
>>> +
>>>  pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>>  enum pci_channel_state state,
>>>  pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
>> @@ -191,15
>>> +202,17 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>>>  if (state == pci_channel_io_frozen) {
>>>  pci_walk_dev_affected(dev, report_frozen_detected,
>> &status);
>>>  if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {
>>> -pci_warn(dev, "link reset not possible for RCiEP\n");
>>> -status = PCI_ERS_RESULT_NONE;
>>> -goto failed;
>>> -}
>>> -
>>> -status = reset_link(dev);
>>> -if (status != PCI_ERS_RESULT_RECOVERED) {
>>> -pci_warn(dev, "link reset failed\n");
>>> -goto failed;
>>> +status = flr_on_rciep(dev);
>>> +if (status != PCI_ERS_RESULT_RECOVERED) {
>>> +pci_warn(dev, "function level reset failed\n");
>>> +goto failed;
>>> +}
>>> +} else {
>>> +status = reset_link(dev);
>>> +if (status != PCI_ERS_RESULT_RECOVERED) {
>>> +pci_warn(dev, "link reset failed\n");
>>> +goto failed;
>>> +}
>>>  }
>>>  } else {
>>>  pci_walk_dev_affected(dev, report_normal_detected,
>> &status);
>>

  reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24 17:22 [RFC PATCH 0/9] Add RCEC handling to PCI/AER Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 1/9] pci_ids: Add class code and extended capability for RCEC Sean V Kelley
2020-07-27 10:00   ` Jonathan Cameron
2020-07-27 10:21     ` Jonathan Cameron
2020-07-27 15:22       ` Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 2/9] PCI: Extend Root Port Driver to support RCEC Sean V Kelley
2020-07-27 12:30   ` Jonathan Cameron
2020-07-27 15:05     ` Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 3/9] PCI/portdrv: Add pcie_walk_rcec() to walk RCiEPs associated with RCEC Sean V Kelley
2020-07-27 10:49   ` Jonathan Cameron
2020-07-27 15:21     ` Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 4/9] PCI/AER: Extend AER error handling to RCECs Sean V Kelley
2020-07-27 11:00   ` Jonathan Cameron
2020-07-27 14:58     ` Sean V Kelley
2020-07-27 14:04   ` Jonathan Cameron
2020-07-27 15:00     ` Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 5/9] PCI/AER: Apply function level reset to RCiEP on fatal error Sean V Kelley
2020-07-27 11:17   ` Jonathan Cameron
2020-07-28 13:27     ` Zhuo, Qiuxu
2020-07-28 16:14       ` Sean V Kelley [this message]
2020-07-28 17:02         ` Jonathan Cameron
2020-07-28 17:42           ` Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 6/9] PCI: Add 'rcec' field to pci_dev for associated RCiEPs Sean V Kelley
2020-07-27 11:23   ` Jonathan Cameron
2020-07-27 15:39     ` Sean V Kelley
2020-07-27 16:11     ` Jonathan Cameron
2020-07-27 16:28       ` Sean V Kelley
2020-07-24 17:22 ` [RFC PATCH 7/9] PCI/AER: Add RCEC AER handling Sean V Kelley
2020-07-27 12:22   ` Jonathan Cameron
2020-07-27 15:19     ` Sean V Kelley
2020-07-27 17:14       ` Jonathan Cameron
2020-07-24 17:22 ` [RFC PATCH 8/9] PCI/PME: Add RCEC PME handling Sean V Kelley
2020-08-04  8:35   ` Jay Fang
2020-08-04  9:47     ` Jonathan Cameron
2020-07-24 17:22 ` [RFC PATCH 9/9] PCI/AER: Add RCEC AER error injection support Sean V Kelley
2020-07-27 12:37 ` [RFC PATCH 0/9] Add RCEC handling to PCI/AER Jonathan Cameron
2020-07-27 14:56   ` Sean V Kelley

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