Re: [PATCH] powerpc/mm: Invalidate partition table cache on host proc tbl base update

Suraj Jitindar Singh [off-list ref] writes:

On Thu, 2017-08-03 at 17:35 +1000, Benjamin Herrenschmidt wrote:

quoted

On Thu, 2017-08-03 at 16:30 +1000, Michael Ellerman wrote:

quoted

Suraj Jitindar Singh [off-list ref] writes:
=20

quoted

The host process table base is stored in the partition table by
calling
the function native_register_process_table(). Currently this just
sets
the entry in memory and is missing a proceeding cache
invalidation
instruction. Any update to the partition table should be followed
by a
cache invalidation instruction specifying invalidation of the
caching of
any partition table entries (RIC =3D 2, PRS =3D 0).
=20
We already have a function to update the partition table with the
required cache invalidation instructions -
mmu_partition_table_set_entry().
Update the native_register_process_table() function to call
mmu_partition_table_set_entry(), this ensures all appropriate
invalidation will be performed.

=20
Without this patch the kernel will:
=C2=A0[ ] work normally
=C2=A0[ ] randomly crash
=C2=A0[ ] catch fire

=20
I think we get lucky because OPAL added a "flush the whole world" to
opal_reinit_cpus() but this patch seems to improve general code
"correctness".

I guess there's the possibility of:
[x] randomly crash

But you haven't actually see any right?

This is required to run a powernv kernel as a guest because we need to
know when it's updated its process table location.

Which doesn't currently work for other reasons :)

cheers