[v2,1/1] powerpc/pci: Fix pcibios_setup_device() ordering

Move PCI device setup from pcibios_add_device() and pcibios_fixup_bus() to
pcibios_bus_add_device(). This ensures that platform-specific DMA and IOMMU
setup occurs after the device has been registered in sysfs, which is a
requirement for IOMMU group assignment to work

This fixes IOMMU group assignment for hotplugged devices on pseries, where
the existing behavior results in IOMMU assignment before registration.

Thanks to Lukas Wunner <lukas@wunner.de> for the suggestion.

Signed-off-by: Shawn Anastasio <shawn@anastas.io>
---
 arch/powerpc/kernel/pci-common.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

On 06/09/2019 05:13, Shawn Anastasio wrote:
> Move PCI device setup from pcibios_add_device() and pcibios_fixup_bus() to
> pcibios_bus_add_device(). This ensures that platform-specific DMA and IOMMU
> setup occurs after the device has been registered in sysfs, which is a
> requirement for IOMMU group assignment to work
> 
> This fixes IOMMU group assignment for hotplugged devices on pseries, where
> the existing behavior results in IOMMU assignment before registration.


Although this is a correct approach which we should proceed with, this
breaks adding of SRIOV VFs from pnv_tce_iommu_bus_notifier (and possibly
the bare metal PCI hotplug), I am trying to fix that now...


> 
> Thanks to Lukas Wunner <lukas@wunner.de> for the suggestion.
> 
> Signed-off-by: Shawn Anastasio <shawn@anastas.io>
> ---
>  arch/powerpc/kernel/pci-common.c | 25 +++++++++----------------
>  1 file changed, 9 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index f627e15bb43c..d119c77efb69 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -261,12 +261,6 @@ int pcibios_sriov_disable(struct pci_dev *pdev)
>  
>  #endif /* CONFIG_PCI_IOV */
>  
> -void pcibios_bus_add_device(struct pci_dev *pdev)
> -{
> -	if (ppc_md.pcibios_bus_add_device)
> -		ppc_md.pcibios_bus_add_device(pdev);
> -}
> -
>  static resource_size_t pcibios_io_size(const struct pci_controller *hose)
>  {
>  #ifdef CONFIG_PPC64
> @@ -987,15 +981,17 @@ static void pcibios_setup_device(struct pci_dev *dev)
>  		ppc_md.pci_irq_fixup(dev);
>  }
>  
> -int pcibios_add_device(struct pci_dev *dev)
> +void pcibios_bus_add_device(struct pci_dev *pdev)
>  {
> -	/*
> -	 * We can only call pcibios_setup_device() after bus setup is complete,
> -	 * since some of the platform specific DMA setup code depends on it.
> -	 */
> -	if (dev->bus->is_added)
> -		pcibios_setup_device(dev);
> +	/* Perform platform-specific device setup */
> +	pcibios_setup_device(pdev);
> +
> +	if (ppc_md.pcibios_bus_add_device)
> +		ppc_md.pcibios_bus_add_device(pdev);
> +}
>  
> +int pcibios_add_device(struct pci_dev *dev)
> +{
>  #ifdef CONFIG_PCI_IOV
>  	if (ppc_md.pcibios_fixup_sriov)
>  		ppc_md.pcibios_fixup_sriov(dev);
> @@ -1037,9 +1033,6 @@ void pcibios_fixup_bus(struct pci_bus *bus)
>  
>  	/* Now fixup the bus bus */
>  	pcibios_setup_bus_self(bus);
> -
> -	/* Now fixup devices on that bus */
> -	pcibios_setup_bus_devices(bus);
>  }
>  EXPORT_SYMBOL(pcibios_fixup_bus);
>  
>

On 9/9/19 2:59 AM, Alexey Kardashevskiy wrote:
> 
> 
> On 06/09/2019 05:13, Shawn Anastasio wrote:
>> Move PCI device setup from pcibios_add_device() and pcibios_fixup_bus() to
>> pcibios_bus_add_device(). This ensures that platform-specific DMA and IOMMU
>> setup occurs after the device has been registered in sysfs, which is a
>> requirement for IOMMU group assignment to work
>>
>> This fixes IOMMU group assignment for hotplugged devices on pseries, where
>> the existing behavior results in IOMMU assignment before registration.
> 
> 
> Although this is a correct approach which we should proceed with, this
> breaks adding of SRIOV VFs from pnv_tce_iommu_bus_notifier (and possibly
> the bare metal PCI hotplug), I am trying to fix that now...

Were you able to make any progress? I can think of a couple of ways
to fix SRIOV, but they're not particularly elegant and involve
duplication.

On 28/09/2019 04:33, Shawn Anastasio wrote:
> On 9/9/19 2:59 AM, Alexey Kardashevskiy wrote:
>>
>>
>> On 06/09/2019 05:13, Shawn Anastasio wrote:
>>> Move PCI device setup from pcibios_add_device() and pcibios_fixup_bus() to
>>> pcibios_bus_add_device(). This ensures that platform-specific DMA and IOMMU
>>> setup occurs after the device has been registered in sysfs, which is a
>>> requirement for IOMMU group assignment to work
>>>
>>> This fixes IOMMU group assignment for hotplugged devices on pseries, where
>>> the existing behavior results in IOMMU assignment before registration.
>>
>>
>> Although this is a correct approach which we should proceed with, this
>> breaks adding of SRIOV VFs from pnv_tce_iommu_bus_notifier (and possibly
>> the bare metal PCI hotplug), I am trying to fix that now...
> 
> Were you able to make any progress? I can think of a couple of ways
> to fix SRIOV, but they're not particularly elegant and involve
> duplication.

A bigger change for ppc+pci is coming from Oliver (I guess with your patch as well) which will tackle this one too, soon.