On 04/29/2014 04:49 PM, Wei Yang wrote: > On Mon, Apr 28, 2014 at 11:35:32PM +1000, Alexey Kardashevskiy wrote: >> On 04/23/2014 12:26 PM, Wei Yang wrote: >>> During the EEH hotplug event, iommu_add_device() will be invoked three times >>> and two of them will trigger warning or error. >>> >>> The three times to invoke the iommu_add_device() are: >>> >>> pci_device_add >>> ... >>> set_iommu_table_base_and_group <- 1st time, fail >>> device_add >>> ... >>> tce_iommu_bus_notifier <- 2nd time, succees >>> pcibios_add_pci_devices >>> ... >>> pcibios_setup_bus_devices <- 3rd time, re-attach >>> >>> The first time fails, since the dev->kobj->sd is not initialized. The >>> dev->kobj->sd is initialized in device_add(). >>> The third time's warning is triggered by the re-attach of the iommu_group. >>> >>> After applying this patch, the error >> >> Nack. >> >> The patch still seems incorrect and we actually need to remove >> tce_iommu_bus_notifier completely as pcibios_setup_bus_devices is called >>from another notifier anyway. Could you please test it? >> >> > > Hi, Alexey, > > Nice to see your comment. Let me show what I got fist. > > Generally, when kernel enumerate on the pci device, following functions will > be invoked. > > pci_device_add > pcibios_setup_bus_device > ... > set_iommu_table_base_and_group > device_add > ... > tce_iommu_bus_notifier > pcibios_fixp_bus > pcibios_add_pci_devices > ... > pcibios_setup_bus_devices > >>From the call flow, we see for a normall pci device, the > pcibios_setup_bus_device() will be invoked twice.
tce_iommu_bus_notifier should not be called for devices during boot-time PCI discovery as the discovery is done from subsys_initcall handler and tce_iommu_bus_notifier is registered as subsys_initcall_sync. Are you sure this is happening? You should see warnings as for PF's EEH but you do not say that. > At the bootup time, none of them succeed to setup the dma, since the PE is not > assigned or the tbl is not set. The iommu tbl and group is setup in > pnv_pci_ioda_setup_DMA(). > > This call flow maintains the same when EEH error happens on Bus PE, while the > behavior is a little different. > > pci_device_add > pcibios_setup_bus_device > ... > set_iommu_table_base_and_group <- fail, kobj->sd is not initialized Sorry, what is uninitialized? The only kobj here is the one in iommu_group and it must have been taken care of before adding a device. > device_add > ... > tce_iommu_bus_notifier <- succeed > pcibios_fixp_bus > pcibios_add_pci_devices > ... > pcibios_setup_bus_devices <- warning, re-attach This is why I am suggesting getting rid of tce_iommu_bus_notifier - we will avoid the warning. > While this call flow will change a little on a VF. For a VF, > pcibios_fixp_bus() will not be invoked. Current behavior is this. You meant pcibios_fixup_bus? I would expect it to get called (from pci_rescan_bus() or something like that?) and this seems to be the problem here. How are VFs added in terms of code flow? Is there any git tree to look at? > pci_device_add > pcibios_setup_bus_device > ... > set_iommu_table_base_and_group <- fail, kobj->sd is not initialized > device_add > ... > tce_iommu_bus_notifier <- succeed > > And if an EEH error happens just on a VF, I believe the same call flow should > go for recovery. (This is not set down, still under discussion with Gavin.) > > My conclusion is: > 1. remove the tce_iommu_bus_notifier completely will make the VF not work. > So I choose to revert the code and attach make the iommu group attachment > just happens in one place. > > BTW, I know my patch is not a perfect one. For a PF, the tbl will still be set > twice. I am not sure why we need to invoke pcibios_setup_device() twice on a > PF, maybe some platform need to fixup some thing after the pci_bus is added. > So I don't remove one of them to solve the problem. > > If you have a better idea, I am glad to take it. > -- Alexey Kardashevskiy IBM OzLabs, LTC Team e-mail: a...@au1.ibm.com notes: Alexey Kardashevskiy/Australia/IBM _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
