arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required

arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required

commit 2687275a5843d1089687f08fc64eb3f3b026a169 upstream.

mem_init() currently relies on knowing the boundaries of the crashkernel
reservation to map such region with page granularity for later
unmapping via set_memory_valid(..., 0). If the crashkernel reservation
is deferred, such boundaries are not known when the linear mapping is
created. Simply parse the command line for "crashkernel" and, if found,
create the linear map with NO_BLOCK_MAPPINGS.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: James Morse <james.morse@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20201119175556.18681-1-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>