diff options
| author | Gabriel L. Somlo <gsomlo@gmail.com> | 2014-05-07 16:52:13 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-05-08 15:40:49 +0200 |
| commit | 87c00572ba05aa8c9db118da75c608f47eb10b9e (patch) | |
| tree | 484e8cc1da97c7302c739364ee0af9bd68cebb0e /arch/x86/kvm/cpuid.c | |
| parent | b63cf42fd1d8c18fab71222321aaf356f63089c9 (diff) | |
kvm: x86: emulate monitor and mwait instructions as nop
Treat monitor and mwait instructions as nop, which is architecturally
correct (but inefficient) behavior. We do this to prevent misbehaving
guests (e.g. OS X <= 10.7) from crashing after they fail to check for
monitor/mwait availability via cpuid.
Since mwait-based idle loops relying on these nop-emulated instructions
would keep the host CPU pegged at 100%, do NOT advertise their presence
via cpuid, to prevent compliant guests from using them inadvertently.
Signed-off-by: Gabriel L. Somlo <somlo@cmu.edu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 17b42fabc842..38a0afe83c6b 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -283,6 +283,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, 0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW); /* cpuid 1.ecx */ const u32 kvm_supported_word4_x86_features = + /* NOTE: MONITOR (and MWAIT) are emulated as NOP, + * but *not* advertised to guests via CPUID ! */ F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ | 0 /* DS-CPL, VMX, SMX, EST */ | 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ | |