Re: [PATCH v5 18/23] powerpc/pci: Handle BAR movement

[Oliver O'Halloran <oohall@gmail.com>]

On Fri, 2019-08-16 at 19:50 +0300, Sergey Miroshnichenko wrote:
> Add pcibios_rescan_prepare()/_done() hooks for the powerpc platform. Now if
> the device's driver supports movable BARs, pcibios_rescan_prepare() will be
> called after the device is stopped, and pcibios_rescan_done() - before it
> resumes. There are no memory requests to this device between the hooks, so
> it it safe to rebuild the EEH address cache during that.
> 
> CC: Oliver O'Halloran <oohall@gmail.com>
> Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
> ---
>  arch/powerpc/kernel/pci-hotplug.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
> index 0b0cf8168b47..18cf13bba228 100644
> --- a/arch/powerpc/kernel/pci-hotplug.c
> +++ b/arch/powerpc/kernel/pci-hotplug.c
> @@ -144,3 +144,13 @@ void pci_hp_add_devices(struct pci_bus *bus)
>  	pcibios_finish_adding_to_bus(bus);
>  }
>  EXPORT_SYMBOL_GPL(pci_hp_add_devices);
> +
> +void pcibios_rescan_prepare(struct pci_dev *pdev)
> +{
> +	eeh_addr_cache_rmv_dev(pdev);
> +}
> +
> +void pcibios_rescan_done(struct pci_dev *pdev)
> +{
> +	eeh_addr_cache_insert_dev(pdev);
> +}

Is this actually sufficent? The PE number for a device is largely
determined by the location of the MMIO BARs. If you move a BAR far
enough the PE number stored in the eeh_pe would need to be updated as
well.