"Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> writes:
> proto-vsid is built using both mmu context id and ESID. We should not have
> overlapping bits between those. That will result in us having vsid
> collision. With the current code we missed masking the top bits of effective
> address. This implies for kernel address we ended up using the top 4 bits
> as part of proto-vsid, which is wrong. For the kernel we should have the
> below mapping
>
> 0xf000000000000000 -> 0x7ffff (19 bits context + 6 bits ESID ).
>
> Without the patch we endup with
> 0xf000000000000000 -> 0xf7ffff (0x7ffff | 0xf00000)
As discussed offline, this is missing the << 6.
Which means we end up with:
ea = 0xf000000000000000
context = 0x7ffff
proto_vsid = (0x7ffff << 6 | 0xf000000000000000 >> 40)
= (0x1ffffc0 | 0xf00000)
= 0x1ffffc0
ie. the proto-vsid is not affected by the extra bits. Same is true for
the 0xc/d/e regions.
So there is no bug here, as long as we use the current mapping from
kernel EA to context ID.
I'll merge this into next.
cheers
