KVM: x86: expose MSR_TSC_AUX to userspace

If we do not do this, it is not properly saved and restored across
migration.  Windows notices due to its self-protection mechanisms,
and is very upset about it (blue screen of death).

Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 036e4bc..f1d6501 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -951,7 +951,7 @@ static u32 msrs_to_save[] = {
        MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
 #endif
        MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
-       MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS
+       MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
 };
 
 static unsigned num_msrs_to_save;
@@ -4028,16 +4028,17 @@ static void kvm_init_msr_list(void)
 
                /*
                 * Even MSRs that are valid in the host may not be exposed
-                * to the guests in some cases.  We could work around this
-                * in VMX with the generic MSR save/load machinery, but it
-                * is not really worthwhile since it will really only
-                * happen with nested virtualization.
+                * to the guests in some cases.
                 */
                switch (msrs_to_save[i]) {
                case MSR_IA32_BNDCFGS:
                        if (!kvm_x86_ops->mpx_supported())
                                continue;
                        break;
+               case MSR_TSC_AUX:
+                       if (!kvm_x86_ops->rdtscp_supported())
+                               continue;
+                       break;
                default:
                        break;
                }