[PATCH v39 07/24] x86/cpu/intel: Add nosgx kernel parameter

From: Jarkko Sakkinen
Date: Sat Oct 03 2020 - 00:51:23 EST


Add kernel parameter to disable Intel SGX kernel support.

Tested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Reviewed-by: Darren Kenny <darren.kenny@xxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 2 ++
arch/x86/kernel/cpu/feat_ctl.c | 9 +++++++++
2 files changed, 11 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 115c50f4e927..7ff2b35a1b8e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3356,6 +3356,8 @@

nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.

+ nosgx [X86-64,SGX] Disables Intel SGX kernel support.
+
nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
and disable the IO APIC. legacy for "maxcpus=0".

diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
index c3afcd2e4342..1837df39527f 100644
--- a/arch/x86/kernel/cpu/feat_ctl.c
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -101,6 +101,15 @@ static void clear_sgx_caps(void)
setup_clear_cpu_cap(X86_FEATURE_SGX2);
}

+static int __init nosgx(char *str)
+{
+ clear_sgx_caps();
+
+ return 0;
+}
+
+early_param("nosgx", nosgx);
+
void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
{
bool tboot = tboot_enabled();
--
2.25.1