Subject: Re: [PATCH V10 10/12] powerpc/eeh: Support error recovery for VF PE

From: Alexey Kardashevskiy <[email-masked]>
Date: Mon, 2 Nov 2015 10:40:36 +1100

On 11/01/2015 12:53 PM, Wei Yang wrote:
> On Fri, Oct 30, 2015 at 04:20:48PM +1100, Alexey Kardashevskiy wrote:
>> On 10/26/2015 02:16 PM, Wei Yang wrote:
>>> Different from PCI bus dependent PE, PE for VFs doesn't have the
>>
>> s/Different from/Unlike/
>>
>
> Will change in next version.
>
>>
>>> primary bus, on which the PCI hotplug is implemented. The patch
>>> supports error recovery, especially the PCI hotplug for VF's PE.
>>
>> The patch adds support for error recovery of what exactly?
>> What is "especially" about?
>>
>
> PFs are enumerated on PCI bus, while VFs are created by PF's driver.
>
> In EEH recovery, it has two cases.
> 1. Device and driver is EEH aware, error handlers are called.
> 2. Device and driver is not EEH aware, un-plug the device and plug it again by
>     enumerating it.
>
> The special thing happens on the second case. For a PF, we could use the
> original pci core to enumerate the bus, while for VF, we need to record the VF
> which are un-plugged then plug it again.

Right. This should have been the actual commit log.

>>
>>> The hotplug on VF's PE is implemented based on VFs, instead of
>>> PCI bus any more.
>>
>> Needs rephrase.
>>
>> Is this patch about EEH error recovery, i.e. unplug VF, re-plug VF? Why does
>> the commit log talk about PE hotplug? I thought we do VF (i.e. PCI device)
>> hotplug, not PE.
>>
>
> Hmm... unlike the Bus PE for PFs, VF PE is dynamically created and released
> when VFs are created and released.

Sure. PEs are created/released, not plugged/unplugged (VFs are), that was 
my point.

>
>>
>>>
>>> [gwshan: changelog and code refactoring]
>>> Signed-off-by: Wei Yang <[email-masked]>
>>> Acked-by: Gavin Shan <[email-masked]>
>>> ---
>>>   arch/powerpc/include/asm/eeh.h   |   1 +
>>>   arch/powerpc/kernel/eeh.c        |   8 ++++
>>>   arch/powerpc/kernel/eeh_driver.c | 100 +++++++++++++++++++++++++++++++--------
>>>   arch/powerpc/kernel/eeh_pe.c     |   3 +-
>>>   4 files changed, 90 insertions(+), 22 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
>>> index 331c856..ea1f13c4 100644
>>> --- a/arch/powerpc/include/asm/eeh.h
>>> +++ b/arch/powerpc/include/asm/eeh.h
>>> @@ -142,6 +142,7 @@ struct eeh_dev {
>>>   	struct pci_controller *phb;	/* Associated PHB		*/
>>>   	struct pci_dn *pdn;		/* Associated PCI device node	*/
>>>   	struct pci_dev *pdev;		/* Associated PCI device	*/
>>> +	int    in_error;		/* Error flag for eeh_dev	*/
>>
>> Make it "bool".
>>
>
> Will change it in next version.
>
>>
>>>   	struct pci_dev *physfn;		/* Associated PF PORT		*/
>>>   	struct pci_bus *bus;		/* PCI bus for partial hotplug	*/
>>>   };
>>> diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
>>> index af9b597..28e4d73 100644
>>> --- a/arch/powerpc/kernel/eeh.c
>>> +++ b/arch/powerpc/kernel/eeh.c
>>> @@ -1227,6 +1227,14 @@ void eeh_remove_device(struct pci_dev *dev)
>>>   	 * from the parent PE during the BAR resotre.
>>>   	 */
>>>   	edev->pdev = NULL;
>>> +
>>> +	/*
>>> +	 * The flag "in_error" is used to trace EEH devices for VFs
>>> +	 * in error state or not. It's set in eeh_report_error(). If
>>> +	 * it's not set, eeh_report_{reset,resume}() won't be called
>>> +	 * for the VF EEH device.
>>> +	 */
>>> +	edev->in_error = 0;
>>>   	dev->dev.archdata.edev = NULL;
>>>   	if (!(edev->pe->state & EEH_PE_KEEP))
>>>   		eeh_rmv_from_parent_pe(edev);
>>> diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
>>> index 89eb4bc..99868e2 100644
>>> --- a/arch/powerpc/kernel/eeh_driver.c
>>> +++ b/arch/powerpc/kernel/eeh_driver.c
>>> @@ -211,6 +211,7 @@ static void *eeh_report_error(void *data, void *userdata)
>>>   	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
>>>   	if (*res == PCI_ERS_RESULT_NONE) *res = rc;
>>>
>>> +	edev->in_error = 1;
>>>   	eeh_pcid_put(dev);
>>>   	return NULL;
>>>   }
>>> @@ -282,7 +283,8 @@ static void *eeh_report_reset(void *data, void *userdata)
>>>
>>>   	if (!driver->err_handler ||
>>>   	    !driver->err_handler->slot_reset ||
>>> -	    (edev->mode & EEH_DEV_NO_HANDLER)) {
>>> +	    (edev->mode & EEH_DEV_NO_HANDLER) ||
>>> +	    (!edev->in_error)) {
>>>   		eeh_pcid_put(dev);
>>>   		return NULL;
>>>   	}
>>> @@ -339,14 +341,16 @@ static void *eeh_report_resume(void *data, void *userdata)
>>>
>>
>> bood was_in_error = edev->in_error;
>> edev->in_error = false;
>>
>> then use was_in_error below and there is no need to replace return with goto,
>> etc -> slightly simpler code.
>>
>
> Will change it in next version.
>
>>
>>>   	if (!driver->err_handler ||
>>>   	    !driver->err_handler->resume ||
>>> -	    (edev->mode & EEH_DEV_NO_HANDLER)) {
>>> +	    (edev->mode & EEH_DEV_NO_HANDLER) ||
>>> +	    (!edev->in_error)) {
>>>   		edev->mode &= ~EEH_DEV_NO_HANDLER;
>>> -		eeh_pcid_put(dev);
>>> -		return NULL;
>>> +		goto out;
>>>   	}
>>>
>>>   	driver->err_handler->resume(dev);
>>>
>>> +out:
>>> +	edev->in_error = 0;
>>>   	eeh_pcid_put(dev);
>>>   	return NULL;
>>>   }
>>> @@ -386,12 +390,38 @@ static void *eeh_report_failure(void *data, void *userdata)
>>>   	return NULL;
>>>   }
>>>
>>> +static void *eeh_add_virt_device(void *data, void *userdata)
>>> +{
>>> +	struct pci_driver *driver;
>>> +	struct eeh_dev *edev = (struct eeh_dev *)data;
>>> +	struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
>>> +	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
>>> +
>>> +	if (!(edev->physfn)) {
>>> +		pr_warn("%s: EEH dev %04x:%02x:%02x.%01x not for VF\n",
>>> +			__func__, edev->phb->global_number, pdn->busno,
>>> +			PCI_SLOT(pdn->devfn), PCI_FUNC(pdn->devfn));
>>> +		return NULL;
>>> +	}
>>> +
>>> +	driver = eeh_pcid_get(dev);
>>> +	if (driver) {
>>> +		eeh_pcid_put(dev);
>>> +		if (driver->err_handler)
>>> +			return NULL;
>>> +	}
>>> +
>>> +	pci_iov_virtfn_add(edev->physfn, pdn->vf_index, 0);
>>> +	return NULL;
>>> +}
>>> +
>>>   static void *eeh_rmv_device(void *data, void *userdata)
>>>   {
>>>   	struct pci_driver *driver;
>>>   	struct eeh_dev *edev = (struct eeh_dev *)data;
>>>   	struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
>>>   	int *removed = (int *)userdata;
>>> +	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
>>>
>>>   	/*
>>>   	 * Actually, we should remove the PCI bridges as well.
>>> @@ -416,7 +446,7 @@ static void *eeh_rmv_device(void *data, void *userdata)
>>>   	driver = eeh_pcid_get(dev);
>>>   	if (driver) {
>>>   		eeh_pcid_put(dev);
>>> -		if (driver->err_handler)
>>> +		if (removed && driver->err_handler)
>>>   			return NULL;
>>>   	}
>>>
>>> @@ -425,11 +455,23 @@ static void *eeh_rmv_device(void *data, void *userdata)
>>>   		 pci_name(dev));
>>>   	edev->bus = dev->bus;
>>>   	edev->mode |= EEH_DEV_DISCONNECTED;
>>> -	(*removed)++;
>>> +	if (removed)
>>> +		(*removed)++;
>>>
>>> -	pci_lock_rescan_remove();
>>> -	pci_stop_and_remove_bus_device(dev);
>>> -	pci_unlock_rescan_remove();
>>> +	if (edev->physfn) {
>>> +		pci_iov_virtfn_remove(edev->physfn, pdn->vf_index, 0);
>>> +		edev->pdev = NULL;
>>> +
>>> +		/*
>>> +		 * We have to set the VF PE number to invalid one, which is
>>> +		 * required to plug the VF successfully.
>>> +		 */
>>> +		pdn->pe_number = IODA_INVALID_PE;
>>> +	} else {
>>> +		pci_lock_rescan_remove();
>>> +		pci_stop_and_remove_bus_device(dev);
>>> +		pci_unlock_rescan_remove();
>>> +	}
>>>
>>>   	return NULL;
>>>   }
>>> @@ -548,6 +590,7 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus)
>>>   	struct pci_bus *frozen_bus = eeh_pe_bus_get(pe);
>>>   	struct timeval tstamp;
>>>   	int cnt, rc, removed = 0;
>>> +	struct eeh_dev *edev;
>>>
>>>   	/* pcibios will clear the counter; save the value */
>>>   	cnt = pe->freeze_count;
>>> @@ -561,12 +604,15 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus)
>>>   	 */
>>>   	eeh_pe_state_mark(pe, EEH_PE_KEEP);
>>>   	if (bus) {
>>> -		pci_lock_rescan_remove();
>>> -		pcibios_remove_pci_devices(bus);
>>> -		pci_unlock_rescan_remove();
>>> -	} else if (frozen_bus) {
>>> +		if (pe->type & EEH_PE_VF)
>>> +			eeh_pe_dev_traverse(pe, eeh_rmv_device, NULL);
>>
>>
>> I believe the rule is that if one branch of "if" uses curly braces, then the
>> other should have them too.
>>
>
> Thanks for reminding, will fix it in next version.

I thought checkpatch.pl checks for it but apparently it does not.

>>
>>> +		else {
>>> +			pci_lock_rescan_remove();
>>> +			pcibios_remove_pci_devices(bus);
>>> +			pci_unlock_rescan_remove();
>>> +		}
>>> +	} else if (frozen_bus)
>>>   		eeh_pe_dev_traverse(pe, eeh_rmv_device, &removed);
>>> -	}
>>>
>>>   	/*
>>>   	 * Reset the pci controller. (Asserts RST#; resets config space).
>>> @@ -607,14 +653,22 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus)
>>>   		 * PE. We should disconnect it so the binding can be
>>>   		 * rebuilt when adding PCI devices.
>>>   		 */
>>> +		edev = list_first_entry(&pe->edevs, struct eeh_dev, list);
>>>   		eeh_pe_traverse(pe, eeh_pe_detach_dev, NULL);
>>> -		pcibios_add_pci_devices(bus);
>>> +		if (pe->type & EEH_PE_VF)
>>
>> Move "edev = list_first_entry(&pe->edevs, struct eeh_dev, list)" here. You
>> could actually do:
>>
>> eeh_add_virt_device(list_first_entry(&pe->edevs, struct eeh_dev, list), NULL);
>>
>> and drop local variable @edev. Or move it to this scope. Dunno.
>>
>
> Hmm... as I know, in eeh_pe_detach_dev() will remove the edev from pe's edevs
> list.
>
>>
>>> +			eeh_add_virt_device(edev, NULL);
>>> +		else
>>> +			pcibios_add_pci_devices(bus);
>>>   	} else if (frozen_bus && removed) {
>>>   		pr_info("EEH: Sleep 5s ahead of partial hotplug\n");
>>>   		ssleep(5);
>>>
>>> +		edev = list_first_entry(&pe->edevs, struct eeh_dev, list);
>>>   		eeh_pe_traverse(pe, eeh_pe_detach_dev, NULL);
>>> -		pcibios_add_pci_devices(frozen_bus);
>>> +		if (pe->type & EEH_PE_VF)
>>
>>
>> The same comment as above.
>>
>>> +			eeh_add_virt_device(edev, NULL);
>>> +		else
>>> +			pcibios_add_pci_devices(frozen_bus);
>>>   	}
>>>   	eeh_pe_state_clear(pe, EEH_PE_KEEP);
>>>
>>> @@ -792,11 +846,15 @@ perm_error:
>>>   	 * the their PCI config any more.
>>>   	 */
>>>   	if (frozen_bus) {
>>> -		eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);
>>> -
>>> -		pci_lock_rescan_remove();
>>> -		pcibios_remove_pci_devices(frozen_bus);
>>> -		pci_unlock_rescan_remove();
>>> +		if (pe->type & EEH_PE_VF) {
>>> +			eeh_pe_dev_traverse(pe, eeh_rmv_device, NULL);
>>> +			eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);
>>> +		} else {
>>> +			eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);
>>> +			pci_lock_rescan_remove();
>>> +			pcibios_remove_pci_devices(frozen_bus);
>>> +			pci_unlock_rescan_remove();
>>> +		}
>>>   	}
>>>   }
>>>
>>> diff --git a/arch/powerpc/kernel/eeh_pe.c b/arch/powerpc/kernel/eeh_pe.c
>>> index 260a701..5cde950 100644
>>> --- a/arch/powerpc/kernel/eeh_pe.c
>>> +++ b/arch/powerpc/kernel/eeh_pe.c
>>> @@ -914,7 +914,8 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe)
>>>   	if (pe->type & EEH_PE_PHB) {
>>>   		bus = pe->phb->bus;
>>>   	} else if (pe->type & EEH_PE_BUS ||
>>> -		   pe->type & EEH_PE_DEVICE) {
>>> +		   pe->type & EEH_PE_DEVICE ||
>>> +		   pe->type & EEH_PE_VF) {
>>>   		if (pe->bus) {
>>>   			bus = pe->bus;
>>>   			goto out;
>>>

-- 
Alexey