Subject: [PATCH] of/irq: Fix msi-map calculation for nonzero rid-base

From: [email-masked] (David Daney)
Date: Tue, 9 Feb 2016 09:03:11 -0800

On 02/09/2016 03:04 AM, Robin Murphy wrote:
> The existing msi-map code is fine for shifting the entire RID space
> upwards, but attempting finer-grained remapping reveals a bug. It turns
> out that we are mistakenly treating the msi-base part as an offset, not
> as a new base to remap onto, so things get squiffy when rid-base is
> nonzero. Fix this, and at the same time add a sanity check against
> having msi-map-mask clash with a nonzero rid-base, as that's another
> thing one can easily get wrong.
>
> CC: <[email-masked]>
> Signed-off-by: Robin Murphy <[email-masked]>

This is equivalent to what I tested yesterday.  Thanks for fixing it...

Acked-by: David Daney <[email-masked]>

> ---
>   drivers/of/irq.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 7ee21ae..e7bfc17 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -635,6 +635,13 @@ static u32 __of_msi_map_rid(struct device *dev, struct device_node **np,
>   		msi_base = be32_to_cpup(msi_map + 2);
>   		rid_len = be32_to_cpup(msi_map + 3);
>
> +		if (rid_base & ~map_mask) {
> +			dev_err(parent_dev,
> +				"Invalid msi-map translation - msi-map-mask (0x%x) ignores rid-base (0x%x)\n",
> +				map_mask, rid_base);
> +			return rid_out;
> +		}
> +
>   		msi_controller_node = of_find_node_by_phandle(phandle);
>
>   		matched = (masked_rid >= rid_base &&
> @@ -654,7 +661,7 @@ static u32 __of_msi_map_rid(struct device *dev, struct device_node **np,
>   	if (!matched)
>   		return rid_out;
>
> -	rid_out = masked_rid + msi_base;
> +	rid_out = masked_rid - rid_base + msi_base;
>   	dev_dbg(dev,
>   		"msi-map at: %s, using mask %08x, rid-base: %08x, msi-base: %08x, length: %08x, rid: %08x -> %08x\n",
>   		dev_name(parent_dev), map_mask, rid_base, msi_base,
>