x86/cpu/intel: Add a nosgx kernel parameter

mainline inclusion
from mainline-v5.11-rc1
commit 38853a30
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SIGI


CVE: NA

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

Add a kernel parameter to disable SGX kernel support and document it.

 [ bp: Massage. ]

Intel-SIG: commit 38853a30 x86/cpu/intel: Add a nosgx kernel parameter
Backport for SGX Foundations support

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Tested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-9-jarkko@kernel.org


Signed-off-by: Fan Du <fan.du@intel.com> #openEuler_contributor
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
Reviewed-by: Bamvor Zhang <bamvor.zhang@suse.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>