From: Sean Christopherson sean.j.christopherson@intel.com
mainline inclusion from mainline-v5.11-rc1 commit 224ab3527f89f69ae57dc53555826667ac46a3cc category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4SIGI CVE: NA
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Kernel support for SGX is ultimately decided by the state of the launch control bits in the feature control MSR (MSR_IA32_FEAT_CTL). If the hardware supports SGX, but neglects to support flexible launch control, the kernel will not enable SGX.
Enable SGX at feature control MSR initialization and update the associated X86_FEATURE flags accordingly. Disable X86_FEATURE_SGX (and all derivatives) if the kernel is not able to establish itself as the authority over SGX Launch Control.
All checks are performed for each logical CPU (not just boot CPU) in order to verify that MSR_IA32_FEATURE_CONTROL is correctly configured on all CPUs. All SGX code in this series expects the same configuration from all CPUs.
This differs from VMX where X86_FEATURE_VMX is intentionally cleared only for the current CPU so that KVM can provide additional information if KVM fails to load like which CPU doesn't support VMX. There’s not much the kernel or an administrator can do to fix the situation, so SGX neglects to convey additional details about these kinds of failures if they occur.
Intel-SIG: commit 224ab3527f89 x86/cpu/intel: Detect SGX support Backport for SGX Foundations support
Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com Co-developed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Borislav Petkov bp@suse.de Acked-by: Jethro Beekman jethro@fortanix.com Link: https://lkml.kernel.org/r/20201112220135.165028-8-jarkko@kernel.org Signed-off-by: Fan Du fan.du@intel.com #openEuler_contributor Signed-off-by: Laibin Qiu qiulaibin@huawei.com --- arch/x86/kernel/cpu/feat_ctl.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c index 29a3bedabd06..d38e97325018 100644 --- a/arch/x86/kernel/cpu/feat_ctl.c +++ b/arch/x86/kernel/cpu/feat_ctl.c @@ -93,16 +93,32 @@ static void init_vmx_capabilities(struct cpuinfo_x86 *c) } #endif /* CONFIG_X86_VMX_FEATURE_NAMES */
+static void clear_sgx_caps(void) +{ + setup_clear_cpu_cap(X86_FEATURE_SGX); + setup_clear_cpu_cap(X86_FEATURE_SGX_LC); +} + void init_ia32_feat_ctl(struct cpuinfo_x86 *c) { bool tboot = tboot_enabled(); + bool enable_sgx; u64 msr;
if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) { clear_cpu_cap(c, X86_FEATURE_VMX); + 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_caps;
@@ -124,13 +140,16 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) 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_caps: set_cpu_cap(c, X86_FEATURE_MSR_IA32_FEAT_CTL);
if (!cpu_has(c, X86_FEATURE_VMX)) - return; + goto update_sgx;
if ( (tboot && !(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX)) || (!tboot && !(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX))) { @@ -143,4 +162,12 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) init_vmx_capabilities(c); #endif } + +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(); + } }