linux-kernel - Re: [PATCH 1/1] of/pci: Add IORESOURCE_MEM_64 to resource flags for 64-bit memory addresses

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Date:   Thu, 15 Apr 2021 13:59:52 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Leonardo Bras <leobras.c@...il.com>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        PCI <linux-pci@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 1/1] of/pci: Add IORESOURCE_MEM_64 to resource flags for
 64-bit memory addresses

+PPC and PCI lists

On Thu, Apr 15, 2021 at 1:01 PM Leonardo Bras <leobras.c@...il.com> wrote:
>
> Many other resource flag parsers already add this flag when the input
> has bits 24 & 25 set, so update this one to do the same.

Many others? Looks like sparc and powerpc to me. Those would be the
ones I worry about breaking. Sparc doesn't use of/address.c so it's
fine. Powerpc version of the flags code was only fixed in 2019, so I
don't think powerpc will care either.

I noticed both sparc and powerpc set PCI_BASE_ADDRESS_MEM_TYPE_64 in
the flags. AFAICT, that's not set anywhere outside of arch code. So
never for riscv, arm and arm64 at least. That leads me to
pci_std_update_resource() which is where the PCI code sets BARs and
just copies the flags in PCI_BASE_ADDRESS_MEM_MASK ignoring
IORESOURCE_* flags. So it seems like 64-bit is still not handled and
neither is prefetch.

> Some devices (like virtio-net) have more than one memory resource
> (like MMIO32 and MMIO64) and without this flag it would be needed to
> verify the address range to know which one is which.
>
> Signed-off-by: Leonardo Bras <leobras.c@...il.com>
> ---
>  drivers/of/address.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 73ddf2540f3f..dc7147843783 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -116,9 +116,12 @@ static unsigned int of_bus_pci_get_flags(const __be32 *addr)
>                 flags |= IORESOURCE_IO;
>                 break;
>         case 0x02: /* 32 bits */
> -       case 0x03: /* 64 bits */
>                 flags |= IORESOURCE_MEM;
>                 break;
> +
> +       case 0x03: /* 64 bits */
> +               flags |= IORESOURCE_MEM | IORESOURCE_MEM_64;
> +               break;
>         }
>         if (w & 0x40000000)
>                 flags |= IORESOURCE_PREFETCH;
> --
> 2.30.2
>