[PATCH v2 5/5] PCI/powerpc/eeh: Add pcibios hooks for preparing to rescan
Sergey Miroshnichenko
s.miroshnichenko at yadro.com
Tue Sep 11 02:00:52 AEST 2018
Hello Sam,
On 9/10/18 8:03 AM, Sam Bobroff wrote:
> Hi Sergey,
>
> On Thu, Sep 06, 2018 at 02:57:52PM +0300, Sergey Miroshnichenko wrote:
>> Reading an empty slot returns all ones, which triggers a false
>> EEH error event on PowerNV.
>>
>> New callbacks pcibios_rescan_prepare/done are introduced to
>> pause/resume the EEH during rescan.
>
> If I understand it correctly, this temporarily disables EEH for config space
> accesses on the whole PHB while the rescan runs. Is it possible that a
> real EEH event could be missed if it occurred during the rescan?
>
> Even if it's not possible, I think it would be good to mention that in a
> comment.
Yes, missing a real EEH event is possible, unfortunately, and it is
indeed worth mentioning.
To reduce this probability the next patchset I'll post in a few days
among other things puts all the affected device drivers to pause during
rescan, mainly because of moving BARs and bridge windows, but it will
also help here a bit.
>
>> Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko at yadro.com>
>> ---
>> arch/powerpc/include/asm/eeh.h | 2 ++
>> arch/powerpc/kernel/eeh.c | 12 +++++++++++
>> arch/powerpc/platforms/powernv/eeh-powernv.c | 22 ++++++++++++++++++++
>> drivers/pci/probe.c | 14 +++++++++++++
>> include/linux/pci.h | 2 ++
>> 5 files changed, 52 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
>> index 219637ea69a1..926c3e31df99 100644
>> --- a/arch/powerpc/include/asm/eeh.h
>> +++ b/arch/powerpc/include/asm/eeh.h
>> @@ -219,6 +219,8 @@ struct eeh_ops {
>> int (*next_error)(struct eeh_pe **pe);
>> int (*restore_config)(struct pci_dn *pdn);
>> int (*notify_resume)(struct pci_dn *pdn);
>> + int (*pause)(struct pci_bus *bus);
>> + int (*resume)(struct pci_bus *bus);
>
> I think these names are a bit too generic, what about naming them
> pause_bus()/resume_bus() or even prepare_rescan()/rescan_done()?
>
Thanks! I will rename them to rescan_prepare/rescan_done to make friends
with reset_prepare/reset_done from struct pci_error_handlers.
>> };
>>
>> extern int eeh_subsystem_flags;
>> diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
>> index 6ebba3e48b01..9fb5012f389d 100644
>> --- a/arch/powerpc/kernel/eeh.c
>> +++ b/arch/powerpc/kernel/eeh.c
>> @@ -1831,3 +1831,15 @@ static int __init eeh_init_proc(void)
>> return 0;
>> }
>> __initcall(eeh_init_proc);
>> +
>> +void pcibios_rescan_prepare(struct pci_bus *bus)
>> +{
>> + if (eeh_ops && eeh_ops->pause)
>> + eeh_ops->pause(bus);
>> +}
>> +
>> +void pcibios_rescan_done(struct pci_bus *bus)
>> +{
>> + if (eeh_ops && eeh_ops->resume)
>> + eeh_ops->resume(bus);
>> +}
>> diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c
>> index 3c1beae29f2d..9724a58afcd2 100644
>> --- a/arch/powerpc/platforms/powernv/eeh-powernv.c
>> +++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
>> @@ -59,6 +59,26 @@ void pnv_pcibios_bus_add_device(struct pci_dev *pdev)
>> eeh_sysfs_add_device(pdev);
>> }
>>
>> +static int pnv_eeh_pause(struct pci_bus *bus)
>> +{
>> + struct pci_controller *hose = pci_bus_to_host(bus);
>> + struct pnv_phb *phb = hose->private_data;
>> +
>> + phb->flags &= ~PNV_PHB_FLAG_EEH;
>> + disable_irq(eeh_event_irq);
>> + return 0;
>> +}
>> +
>> +static int pnv_eeh_resume(struct pci_bus *bus)
>> +{
>> + struct pci_controller *hose = pci_bus_to_host(bus);
>> + struct pnv_phb *phb = hose->private_data;
>> +
>> + enable_irq(eeh_event_irq);
>> + phb->flags |= PNV_PHB_FLAG_EEH;
>> + return 0;
>> +}
>> +
>> static int pnv_eeh_init(void)
>> {
>> struct pci_controller *hose;
>> @@ -1710,6 +1730,8 @@ static struct eeh_ops pnv_eeh_ops = {
>> .write_config = pnv_eeh_write_config,
>> .next_error = pnv_eeh_next_error,
>> .restore_config = pnv_eeh_restore_config,
>> + .pause = pnv_eeh_pause,
>> + .resume = pnv_eeh_resume,
>> .notify_resume = NULL
>> };
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index ac876e32de4b..4a9045364809 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -2801,6 +2801,14 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
>> {
>> }
>>
>> +void __weak pcibios_rescan_prepare(struct pci_bus *bus)
>> +{
>> +}
>> +
>> +void __weak pcibios_rescan_done(struct pci_bus *bus)
>> +{
>> +}
>> +
>> struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>> struct pci_ops *ops, void *sysdata, struct list_head *resources)
>> {
>> @@ -3055,9 +3063,15 @@ unsigned int pci_rescan_bus_bridge_resize(struct pci_dev *bridge)
>> unsigned int pci_rescan_bus(struct pci_bus *bus)
>> {
>> unsigned int max;
>> + struct pci_bus *root = bus;
>> +
>> + while (!pci_is_root_bus(root))
>> + root = root->parent;
>>
>> + pcibios_rescan_prepare(root);
>> max = pci_scan_child_bus(bus);
>> pci_assign_unassigned_bus_resources(bus);
>> + pcibios_rescan_done(root);
>> pci_bus_add_devices(bus);
>>
>> return max;
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 340029b2fb38..42930731c5a7 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -1929,6 +1929,8 @@ void pcibios_penalize_isa_irq(int irq, int active);
>> int pcibios_alloc_irq(struct pci_dev *dev);
>> void pcibios_free_irq(struct pci_dev *dev);
>> resource_size_t pcibios_default_alignment(void);
>> +void pcibios_rescan_prepare(struct pci_bus *bus);
>> +void pcibios_rescan_done(struct pci_bus *bus);
>>
>> #ifdef CONFIG_HIBERNATE_CALLBACKS
>> extern struct dev_pm_ops pcibios_pm_ops;
>> --
>> 2.17.1
>>
Best regards,
Serge
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