[PATCH 06/16] x86/cpu: Clear VMX feature flag if VMX is not fully enabled

[Sean Christopherson]

Now that the IA32_FEATURE_CONTROL MSR is guaranteed to be configured and
locked, clear the VMX capability flag if the IA32_FEATURE_CONTROL MSR is
not supported or if BIOS disabled VMX, i.e. locked IA32_FEATURE_CONTROL
and did not set the appropriate VMX enable bit.

Signed-off-by: Sean Christopherson <sean.j.christopher...@intel.com>
---
 arch/x86/kernel/cpu/feature_control.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/feature_control.c 
b/arch/x86/kernel/cpu/feature_control.c
index 57b928e64cf5..74c76159a046 100644
--- a/arch/x86/kernel/cpu/feature_control.c
+++ b/arch/x86/kernel/cpu/feature_control.c
@@ -7,13 +7,19 @@
 
 void init_feature_control_msr(struct cpuinfo_x86 *c)
 {
+       bool tboot = tboot_enabled();
        u64 msr;
 
-       if (rdmsrl_safe(MSR_IA32_FEATURE_CONTROL, &msr))
+       if (rdmsrl_safe(MSR_IA32_FEATURE_CONTROL, &msr)) {
+               if (cpu_has(c, X86_FEATURE_VMX)) {
+                       pr_err_once("x86/cpu: VMX disabled, 
IA32_FEATURE_CONTROL MSR unsupported\n");
+                       clear_cpu_cap(c, X86_FEATURE_VMX);
+               }
                return;
+       }
 
        if (msr & FEATURE_CONTROL_LOCKED)
-               return;
+               goto update_caps;
 
        /*
         * Ignore whatever value BIOS left in the MSR to avoid enabling random
@@ -23,8 +29,19 @@ void init_feature_control_msr(struct cpuinfo_x86 *c)
 
        if (cpu_has(c, X86_FEATURE_VMX)) {
                msr |= FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
-               if (tboot_enabled())
+               if (tboot)
                        msr |= FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX;
        }
        wrmsrl(MSR_IA32_FEATURE_CONTROL, msr);
+
+update_caps:
+       if (!cpu_has(c, X86_FEATURE_VMX))
+               return;
+
+       if ((tboot && !(msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX)) ||
+           (!tboot && !(msr & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX))) {
+               pr_err_once("x86/cpu: VMX disabled by BIOS (TXT %s)\n",
+                           tboot ? "enabled" : "disabled");
+               clear_cpu_cap(c, X86_FEATURE_VMX);
+       }
 }
-- 
2.22.0