[PATCH] kvm: x86: revert "emulate monitor and mwait instructions as nop"

[Gabriel L. Somlo]

This reverts commit 87c00572ba05aa8c9db118da75c608f47eb10b9e.

OS X <= 10.7.* are the only known guests which realistically required
this functionality. As it turns out, OS X can be told to forego using
monitor/mwait by passing it "idlehalt=0" as a kernel argument, so we're
better off removing this hack from KVM altogether.

Signed-off-by: Gabriel L. Somlo <somlo@xxxxxxx>
---
 arch/x86/kvm/cpuid.c |  2 --
 arch/x86/kvm/svm.c   |  8 +++-----
 arch/x86/kvm/vmx.c   | 10 ++++------
 3 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 38a0afe..17b42fa 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -283,8 +283,6 @@ 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 */ |
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ec8366c..0e8ef20 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3274,7 +3274,7 @@ static int pause_interception(struct vcpu_svm *svm)
 	return 1;
 }
 
-static int nop_interception(struct vcpu_svm *svm)
+static int invalid_op_interception(struct vcpu_svm *svm)
 {
 	skip_emulated_instruction(&(svm->vcpu));
 	return 1;
@@ -3282,14 +3282,12 @@ static int nop_interception(struct vcpu_svm *svm)
 
 static int monitor_interception(struct vcpu_svm *svm)
 {
-	printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n");
-	return nop_interception(svm);
+	return invalid_op_interception(svm);
 }
 
 static int mwait_interception(struct vcpu_svm *svm)
 {
-	printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n");
-	return nop_interception(svm);
+	return invalid_op_interception(svm);
 }
 
 static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 801332e..577c7df 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5672,22 +5672,20 @@ static int handle_pause(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
-static int handle_nop(struct kvm_vcpu *vcpu)
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
 {
-	skip_emulated_instruction(vcpu);
+	kvm_queue_exception(vcpu, UD_VECTOR);
 	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);
+	return handle_invalid_op(vcpu);
 }
 
 static int handle_monitor(struct kvm_vcpu *vcpu)
 {
-	printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n");
-	return handle_nop(vcpu);
+	return handle_invalid_op(vcpu);
 }
 
 /*
-- 
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/