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From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-sgx@vger.kernel.org
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
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Subject: [PATCH v31 07/21] x86/cpu/intel: Add nosgx kernel parameter
Date:   Mon,  1 Jun 2020 04:16:31 +0300
Message-Id: <20200601011645.794040-8-jarkko.sakkinen@linux.intel.com>
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Add kernel parameter to disable Intel SGX kernel support.

Tested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 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 7bc83f3d9bdf..9f7202a54db6 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3268,6 +3268,8 @@
 
 	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