mainline inclusion
from mainline-v5.13-rc1
commit 13150149
category: bugfix
bugzilla: 172149 https://gitee.com/openeuler/kernel/issues/I4CZ7H
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=13150149aa6d

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

Kernel mode NEON can be used in task or softirq context, but only in
a non-nesting manner, i.e., softirq context is only permitted if the
interrupt was not taken at a point where the kernel was using the NEON
in task context.

This means all users of kernel mode NEON have to be aware of this
limitation, and either need to provide scalar fallbacks that may be much
slower (up to 20x for AES instructions) and potentially less safe, or
use an asynchronous interface that defers processing to a later time
when the NEON is guaranteed to be available.

Given that grabbing and releasing the NEON is cheap, we can relax this
restriction, by increasing the granularity of kernel mode NEON code, and
always disabling softirq processing while the NEON is being used in task
context.
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>
Acked-by: NWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210302090118.30666-4-ardb@kernel.orgSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWei Li <liwei391@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>