powerpc/powernv: wire up rng during setup_arch

stable inclusion
from stable-v5.10.127
commit f78acc4288edf747e8376d50c92cb427e3193ec6
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5XDDK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f78acc4288edf747e8376d50c92cb427e3193ec6



--------------------------------

commit f3eac426 upstream.

The platform's RNG must be available before random_init() in order to be
useful for initial seeding, which in turn means that it needs to be
called from setup_arch(), rather than from an init call.

Complicating things, however, is that POWER8 systems need some per-cpu
state and kmalloc, which isn't available at this stage. So we split
things up into an early phase and a later opportunistic phase. This
commit also removes some noisy log messages that don't add much.

Fixes: a4da0d50 ("powerpc: Implement arch_get_random_long/int() for powernv")
Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Add of_node_put(), use pnv naming, minor change log editing]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220621140849.127227-1-Jason@zx2c4.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>