Now that IA32_FEAT_CTL is always configured and locked for CPUs that are known to support VMX[*], clear the VMX capability flag if the MSR is unsupported or BIOS disabled VMX, i.e. locked IA32_FEAT_CTL and didn't set the appropriate VMX enable bit.
[*] Because init_ia32_feat_ctl() is called from vendors ->c_init(), it's still possible for IA32_FEAT_CTL to be left unlocked when VMX is supported by the CPU. This is not fatal, and will be addressed in a future patch.
Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com --- arch/x86/kernel/cpu/feat_ctl.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c index c4f8f767853b..a46c9e46f937 100644 --- a/arch/x86/kernel/cpu/feat_ctl.c +++ b/arch/x86/kernel/cpu/feat_ctl.c @@ -5,15 +5,21 @@ #include <asm/msr-index.h> #include <asm/processor.h>
+#undef pr_fmt +#define pr_fmt(fmt) "x86/cpu: " fmt + void init_ia32_feat_ctl(struct cpuinfo_x86 *c) { + bool tboot = tboot_enabled(); u64 msr;
- if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) + if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) { + clear_cpu_cap(c, X86_FEATURE_VMX); return; + }
if (msr & FEAT_CTL_LOCKED) - return; + goto update_caps;
/* * Ignore whatever value BIOS left in the MSR to avoid enabling random @@ -29,9 +35,20 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL)) { msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
- if (tboot_enabled()) + if (tboot) msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX; }
wrmsrl(MSR_IA32_FEAT_CTL, msr); + +update_caps: + if (!cpu_has(c, X86_FEATURE_VMX)) + return; + + if ( (tboot && !(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX)) || + (!tboot && !(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX))) { + pr_err_once("VMX (%s TXT) disabled by BIOS\n", + tboot ? "inside" : "outside"); + clear_cpu_cap(c, X86_FEATURE_VMX); + } }