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-rw-r--r--arch/x86/kernel/cpu/feat_ctl.c212
1 files changed, 212 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
new file mode 100644
index 000000000..03851240c
--- /dev/null
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/tboot.h>
+
+#include <asm/cpu.h>
+#include <asm/cpufeature.h>
+#include <asm/msr-index.h>
+#include <asm/processor.h>
+#include <asm/vmx.h>
+
+#undef pr_fmt
+#define pr_fmt(fmt) "x86/cpu: " fmt
+
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+enum vmx_feature_leafs {
+ MISC_FEATURES = 0,
+ PRIMARY_CTLS,
+ SECONDARY_CTLS,
+ TERTIARY_CTLS_LOW,
+ TERTIARY_CTLS_HIGH,
+ NR_VMX_FEATURE_WORDS,
+};
+
+#define VMX_F(x) BIT(VMX_FEATURE_##x & 0x1f)
+
+static void init_vmx_capabilities(struct cpuinfo_x86 *c)
+{
+ u32 supported, funcs, ept, vpid, ign, low, high;
+
+ BUILD_BUG_ON(NVMXINTS != NR_VMX_FEATURE_WORDS);
+
+ /*
+ * The high bits contain the allowed-1 settings, i.e. features that can
+ * be turned on. The low bits contain the allowed-0 settings, i.e.
+ * features that can be turned off. Ignore the allowed-0 settings,
+ * if a feature can be turned on then it's supported.
+ *
+ * Use raw rdmsr() for primary processor controls and pin controls MSRs
+ * as they exist on any CPU that supports VMX, i.e. we want the WARN if
+ * the RDMSR faults.
+ */
+ rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, ign, supported);
+ c->vmx_capability[PRIMARY_CTLS] = supported;
+
+ rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS2, &ign, &supported);
+ c->vmx_capability[SECONDARY_CTLS] = supported;
+
+ /* All 64 bits of tertiary controls MSR are allowed-1 settings. */
+ rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS3, &low, &high);
+ c->vmx_capability[TERTIARY_CTLS_LOW] = low;
+ c->vmx_capability[TERTIARY_CTLS_HIGH] = high;
+
+ rdmsr(MSR_IA32_VMX_PINBASED_CTLS, ign, supported);
+ rdmsr_safe(MSR_IA32_VMX_VMFUNC, &ign, &funcs);
+
+ /*
+ * Except for EPT+VPID, which enumerates support for both in a single
+ * MSR, low for EPT, high for VPID.
+ */
+ rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, &ept, &vpid);
+
+ /* Pin, EPT, VPID and VM-Func are merged into a single word. */
+ WARN_ON_ONCE(supported >> 16);
+ WARN_ON_ONCE(funcs >> 4);
+ c->vmx_capability[MISC_FEATURES] = (supported & 0xffff) |
+ ((vpid & 0x1) << 16) |
+ ((funcs & 0xf) << 28);
+
+ /* EPT bits are full on scattered and must be manually handled. */
+ if (ept & VMX_EPT_EXECUTE_ONLY_BIT)
+ c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_EXECUTE_ONLY);
+ if (ept & VMX_EPT_AD_BIT)
+ c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_AD);
+ if (ept & VMX_EPT_1GB_PAGE_BIT)
+ c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_1GB);
+
+ /* Synthetic APIC features that are aggregates of multiple features. */
+ if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) &&
+ (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_APIC_ACCESSES)))
+ c->vmx_capability[MISC_FEATURES] |= VMX_F(FLEXPRIORITY);
+
+ if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) &&
+ (c->vmx_capability[SECONDARY_CTLS] & VMX_F(APIC_REGISTER_VIRT)) &&
+ (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_INTR_DELIVERY)) &&
+ (c->vmx_capability[MISC_FEATURES] & VMX_F(POSTED_INTR)))
+ c->vmx_capability[MISC_FEATURES] |= VMX_F(APICV);
+
+ /* Set the synthetic cpufeatures to preserve /proc/cpuinfo's ABI. */
+ if (c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR))
+ set_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
+ if (c->vmx_capability[MISC_FEATURES] & VMX_F(FLEXPRIORITY))
+ set_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
+ if (c->vmx_capability[MISC_FEATURES] & VMX_F(VIRTUAL_NMIS))
+ set_cpu_cap(c, X86_FEATURE_VNMI);
+ if (c->vmx_capability[SECONDARY_CTLS] & VMX_F(EPT))
+ set_cpu_cap(c, X86_FEATURE_EPT);
+ if (c->vmx_capability[MISC_FEATURES] & VMX_F(EPT_AD))
+ set_cpu_cap(c, X86_FEATURE_EPT_AD);
+ if (c->vmx_capability[MISC_FEATURES] & VMX_F(VPID))
+ set_cpu_cap(c, X86_FEATURE_VPID);
+}
+#endif /* CONFIG_X86_VMX_FEATURE_NAMES */
+
+static int __init nosgx(char *str)
+{
+ setup_clear_cpu_cap(X86_FEATURE_SGX);
+
+ return 0;
+}
+
+early_param("nosgx", nosgx);
+
+void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
+{
+ bool enable_sgx_kvm = false, enable_sgx_driver = false;
+ bool tboot = tboot_enabled();
+ bool enable_vmx;
+ u64 msr;
+
+ if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
+ clear_cpu_cap(c, X86_FEATURE_VMX);
+ clear_cpu_cap(c, X86_FEATURE_SGX);
+ return;
+ }
+
+ enable_vmx = cpu_has(c, X86_FEATURE_VMX) &&
+ IS_ENABLED(CONFIG_KVM_INTEL);
+
+ if (cpu_has(c, X86_FEATURE_SGX) && IS_ENABLED(CONFIG_X86_SGX)) {
+ /*
+ * Separate out SGX driver enabling from KVM. This allows KVM
+ * guests to use SGX even if the kernel SGX driver refuses to
+ * use it. This happens if flexible Launch Control is not
+ * available.
+ */
+ enable_sgx_driver = cpu_has(c, X86_FEATURE_SGX_LC);
+ enable_sgx_kvm = enable_vmx && IS_ENABLED(CONFIG_X86_SGX_KVM);
+ }
+
+ if (msr & FEAT_CTL_LOCKED)
+ goto update_caps;
+
+ /*
+ * 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 (enable_vmx) {
+ msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
+
+ if (tboot)
+ msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX;
+ }
+
+ if (enable_sgx_kvm || enable_sgx_driver) {
+ msr |= FEAT_CTL_SGX_ENABLED;
+ if (enable_sgx_driver)
+ msr |= 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))
+ goto update_sgx;
+
+ if ( (tboot && !(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX)) ||
+ (!tboot && !(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX))) {
+ if (IS_ENABLED(CONFIG_KVM_INTEL))
+ pr_err_once("VMX (%s TXT) disabled by BIOS\n",
+ tboot ? "inside" : "outside");
+ clear_cpu_cap(c, X86_FEATURE_VMX);
+ } else {
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+ init_vmx_capabilities(c);
+#endif
+ }
+
+update_sgx:
+ if (!(msr & FEAT_CTL_SGX_ENABLED)) {
+ if (enable_sgx_kvm || enable_sgx_driver)
+ pr_err_once("SGX disabled by BIOS.\n");
+ clear_cpu_cap(c, X86_FEATURE_SGX);
+ return;
+ }
+
+ /*
+ * VMX feature bit may be cleared due to being disabled in BIOS,
+ * in which case SGX virtualization cannot be supported either.
+ */
+ if (!cpu_has(c, X86_FEATURE_VMX) && enable_sgx_kvm) {
+ pr_err_once("SGX virtualization disabled due to lack of VMX.\n");
+ enable_sgx_kvm = 0;
+ }
+
+ if (!(msr & FEAT_CTL_SGX_LC_ENABLED) && enable_sgx_driver) {
+ if (!enable_sgx_kvm) {
+ pr_err_once("SGX Launch Control is locked. Disable SGX.\n");
+ clear_cpu_cap(c, X86_FEATURE_SGX);
+ } else {
+ pr_err_once("SGX Launch Control is locked. Support SGX virtualization only.\n");
+ clear_cpu_cap(c, X86_FEATURE_SGX_LC);
+ }
+ }
+}