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From:   "Oliver O'Halloran" <oohall@gmail.com>
Date:   Sun, 23 Aug 2020 10:32:42 +1000
Message-ID: <CAOSf1CGjm576cj3mqAqhp0xGE4P5F0ULNBPWxN44kmBLgUh4_A@mail.gmail.com>
Subject: Re: [PATCH] powerpc/pseries: Add pcibios_default_alignment implementation
To:     Shawn Anastasio <shawn@anastas.io>
Cc:     linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        linux-pci <linux-pci@vger.kernel.org>
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On Sat, Aug 22, 2020 at 6:51 AM Shawn Anastasio <shawn@anastas.io> wrote:
>
> Implement pcibios_default_alignment for pseries so that
> resources are page-aligned. The main benefit of this is being
> able to map any resource from userspace via mechanisms like VFIO.

Reviewed-by: Oliver O'Halloran <oohall@gmail.com>

That said, there's nothing power specific about this so we should
probably drop the pcibios hacks and fix the default alignment in the
PCI core.

> This is identical to powernv's implementation.
>
> Signed-off-by: Shawn Anastasio <shawn@anastas.io>
> ---
>  arch/powerpc/platforms/pseries/pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/pci.c b/arch/powerpc/platforms/pseries/pci.c
> index 911534b89c85..6d922c096354 100644
> --- a/arch/powerpc/platforms/pseries/pci.c
> +++ b/arch/powerpc/platforms/pseries/pci.c
> @@ -210,6 +210,11 @@ int pseries_pcibios_sriov_disable(struct pci_dev *pdev)
>  }
>  #endif
>
> +static resource_size_t pseries_pcibios_default_alignment(void)
> +{
> +       return PAGE_SIZE;
> +}
> +
>  static void __init pSeries_request_regions(void)
>  {
>         if (!isa_io_base)
> @@ -231,6 +236,8 @@ void __init pSeries_final_fixup(void)
>
>         eeh_show_enabled();
>
> +       ppc_md.pcibios_default_alignment = pseries_pcibios_default_alignment;
> +
>  #ifdef CONFIG_PCI_IOV
>         ppc_md.pcibios_sriov_enable = pseries_pcibios_sriov_enable;
>         ppc_md.pcibios_sriov_disable = pseries_pcibios_sriov_disable;
> --
> 2.28.0
>