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| 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/vmx.c | |
| parent | b63cf42fd1d8c18fab71222321aaf356f63089c9 (diff) | |
| download | lwn-87c00572ba05aa8c9db118da75c608f47eb10b9e.tar.gz lwn-87c00572ba05aa8c9db118da75c608f47eb10b9e.zip | |
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/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 20 |
1 files changed, 16 insertions, 4 deletions
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, }; |