Re: [PATCH] PPC: PCI: Fix pcibios_io_space_offset() so it works for 32-bit ptr/64-bit rsrcs

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2012-06-05 at 23:50 -0400, Ben Collins wrote:
> The commit introducing pcibios_io_space_offset() was ignoring 32-bit to
> 64-bit sign extention, which is the case on ppc32 with 64-bit resource
> addresses. This only seems to have shown up while running under QEMU for
> e500mc target. It may or may be suboptimal that QEMU has an IO base
> address > 32-bits for the e500-pci implementation, but 1) it's still a
> regression and 2) it's more correct to handle things this way.

See Bjorn, we both did end up getting it wrong :-)

> Signed-off-by: Ben Collins <bcollins@ubuntu.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

>  arch/powerpc/kernel/pci-common.c |    8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index 8e78e93..be9ced7 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -1477,9 +1477,15 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
>  	return pci_enable_resources(dev, mask);
>  }
>  
> +/* Before assuming too much here, take care to realize that we need sign
> + * extension from 32-bit pointers to 64-bit resource addresses to work.
> + */
>  resource_size_t pcibios_io_space_offset(struct pci_controller *hose)
>  {
> -	return (unsigned long) hose->io_base_virt - _IO_BASE;
> +	long vbase = (long)hose->io_base_virt;
> +	long io_base = _IO_BASE;
> +
> +	return (resource_size_t)(vbase - io_base);
>  }
>  
>  static void __devinit pcibios_setup_phb_resources(struct pci_controller *hose, struct list_head *resources)