KVM: VMX: Use VMX feature flag to query BIOS enabling

Replace KVM's manual checks on IA32_FEAT_CTL with a query on the boot
CPU's MSR_IA32_FEAT_CTL and VMX feature flags.  The MSR_IA32_FEAT_CTL
indicates that IA32_FEAT_CTL has been configured and that dependent
features are accurately reflected in cpufeatures, e.g. the VMX flag is
now cleared during boot if VMX isn't fully enabled via IA32_FEAT_CTL,
including the case where the MSR isn't supported.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20191221044513.21680-16-sean.j.christopherson@intel.com

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a026334ffc58894dc4d1eb97f3542d9da5319983..06e0e526270421a89febee5343202556ed7318c6 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2204,31 +2204,8 @@ static __init int cpu_has_kvm_support(void)
 
 static __init int vmx_disabled_by_bios(void)
 {
-       u64 msr;
-
-       rdmsrl(MSR_IA32_FEAT_CTL, msr);
-
-       if (unlikely(!(msr & FEAT_CTL_LOCKED)))
-               return 1;
-
-       /* launched w/ TXT and VMX disabled */
-       if (!(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) &&
-           tboot_enabled())
-               return 1;
-       /* launched w/o TXT and VMX only enabled w/ TXT */
-       if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) &&
-           (msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) &&
-           !tboot_enabled()) {
-               pr_warn("kvm: disable TXT in the BIOS or "
-                       "activate TXT before enabling KVM\n");
-               return 1;
-       }
-       /* launched w/o TXT and VMX disabled */
-       if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) &&
-           !tboot_enabled())
-               return 1;
-
-       return 0;
+       return !boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+              !boot_cpu_has(X86_FEATURE_VMX);
 }
 
 static void kvm_cpu_vmxon(u64 addr)