> -----Original Message----- > From: Marc Zyngier [mailto:marc.zyngier@xxxxxxx] > Sent: Tuesday, February 09, 2016 6:06 AM > To: Robin Murphy <robin.murphy@xxxxxxx>; robh+dt@xxxxxxxxxx; frowand.list@xxxxxxxxx; > grant.likely@xxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx > Cc: mark.rutland@xxxxxxx; david.daney@xxxxxxxxxx; Stuart Yoder <stuart.yoder@xxxxxxx>; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > stable@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] of/irq: Fix msi-map calculation for nonzero rid-base > > Hi Robin, > > On 09/02/16 11:04, 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: <stable@xxxxxxxxxxxxxxx> > > Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> > > Looks like Stuart and you both found the same bug at the same time: > https://lkml.org/lkml/2016/2/8/1066 > > but yours seem more correct to me (the rid_base masking in Stuart's > version seems odd). > > > --- > > 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, > > This computation: masked_rid - rid_base ...doesn't seem right to me. We are taking a rid that has been already masked and subtracting a rid base that has not been masked. I don't see how you can combine masked and unmasked values in the same calculation. Say I have this msi mapping: msi-map = <0x0100 &its 0x11 0x1>; msi-map-mask = <0xff>; masked_rid = 0x0 rid_base = 0x0100 msi_base = 0x11 masked_rid - rid_base is 0x0 - 0x0100...which does not give the msi index/offset we want. Correct final answer should be 0x11. In my patch I masked the rid_base so it can be subtracted from the masked_rid. masked_rid_base = 0x00 msi_base + (masked_rid - masked_rid_base) = 0x11 Stuart -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
