75 lines
1.6 KiB
C
75 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/tboot.h>
|
|
|
|
#include <asm/cpufeature.h>
|
|
#include <asm/msr-index.h>
|
|
#include <asm/processor.h>
|
|
|
|
static void clear_sgx_caps(void)
|
|
{
|
|
setup_clear_cpu_cap(X86_FEATURE_SGX);
|
|
setup_clear_cpu_cap(X86_FEATURE_SGX_LC);
|
|
}
|
|
|
|
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 enable_sgx;
|
|
u64 msr;
|
|
|
|
if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
|
|
clear_sgx_caps();
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Enable SGX if and only if the kernel supports SGX and Launch Control
|
|
* is supported, i.e. disable SGX if the LE hash MSRs can't be written.
|
|
*/
|
|
enable_sgx = cpu_has(c, X86_FEATURE_SGX) &&
|
|
cpu_has(c, X86_FEATURE_SGX_LC) &&
|
|
IS_ENABLED(CONFIG_X86_SGX);
|
|
|
|
if (msr & FEAT_CTL_LOCKED)
|
|
goto update_sgx;
|
|
|
|
/*
|
|
* Ignore whatever value BIOS left in the MSR to avoid enabling random
|
|
* features or faulting on the WRMSR.
|
|
*/
|
|
msr = FEAT_CTL_LOCKED;
|
|
|
|
/*
|
|
* Enable VMX if and only if the kernel may do VMXON at some point,
|
|
* i.e. KVM is enabled, to avoid unnecessarily adding an attack vector
|
|
* for the kernel, e.g. using VMX to hide malicious code.
|
|
*/
|
|
if (cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL)) {
|
|
msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
|
|
|
|
if (tboot_enabled())
|
|
msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX;
|
|
}
|
|
|
|
if (enable_sgx)
|
|
msr |= FEAT_CTL_SGX_ENABLED | FEAT_CTL_SGX_LC_ENABLED;
|
|
|
|
wrmsrl(MSR_IA32_FEAT_CTL, msr);
|
|
|
|
update_sgx:
|
|
if (!(msr & FEAT_CTL_SGX_ENABLED) ||
|
|
!(msr & FEAT_CTL_SGX_LC_ENABLED) || !enable_sgx) {
|
|
if (enable_sgx)
|
|
pr_err_once("SGX disabled by BIOS\n");
|
|
clear_sgx_caps();
|
|
}
|
|
}
|