From 87c00572ba05aa8c9db118da75c608f47eb10b9e Mon Sep 17 00:00:00 2001 From: "Gabriel L. Somlo" Date: Wed, 7 May 2014 16:52:13 -0400 Subject: 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 Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) (limited to 'arch/x86/kvm/vmx.c') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 61e818d80732..6f7463f53ed9 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -5650,12 +5650,24 @@ static int handle_pause(struct kvm_vcpu *vcpu) return 1; } -static int handle_invalid_op(struct kvm_vcpu *vcpu) +static int handle_nop(struct kvm_vcpu *vcpu) { - kvm_queue_exception(vcpu, UD_VECTOR); + skip_emulated_instruction(vcpu); return 1; } +static int handle_mwait(struct kvm_vcpu *vcpu) +{ + printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n"); + return handle_nop(vcpu); +} + +static int handle_monitor(struct kvm_vcpu *vcpu) +{ + printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n"); + return handle_nop(vcpu); +} + /* * To run an L2 guest, we need a vmcs02 based on the L1-specified vmcs12. * We could reuse a single VMCS for all the L2 guests, but we also want the @@ -6617,8 +6629,8 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { [EXIT_REASON_EPT_VIOLATION] = handle_ept_violation, [EXIT_REASON_EPT_MISCONFIG] = handle_ept_misconfig, [EXIT_REASON_PAUSE_INSTRUCTION] = handle_pause, - [EXIT_REASON_MWAIT_INSTRUCTION] = handle_invalid_op, - [EXIT_REASON_MONITOR_INSTRUCTION] = handle_invalid_op, + [EXIT_REASON_MWAIT_INSTRUCTION] = handle_mwait, + [EXIT_REASON_MONITOR_INSTRUCTION] = handle_monitor, [EXIT_REASON_INVEPT] = handle_invept, }; -- cgit v1.2.3