diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 3b0bc4b..da9c3aa 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -46,6 +46,7 @@
 #define KVM_MAX_CPUID_ENTRIES 40
 
 #define DE_VECTOR 0
+#define UD_VECTOR 6
 #define NM_VECTOR 7
 #define DF_VECTOR 8
 #define TS_VECTOR 10
@@ -317,9 +318,6 @@
 	unsigned long cr0;
 	unsigned long cr2;
 	unsigned long cr3;
-	gpa_t para_state_gpa;
-	struct page *para_state_page;
-	gpa_t hypercall_gpa;
 	unsigned long cr4;
 	unsigned long cr8;
 	u64 pdptrs[4]; /* pae */
@@ -622,7 +620,9 @@
 int kvm_mmu_load(struct kvm_vcpu *vcpu);
 void kvm_mmu_unload(struct kvm_vcpu *vcpu);
 
-int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
+
+int kvm_fix_hypercall(struct kvm_vcpu *vcpu);
 
 static inline void kvm_guest_enter(void)
 {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index c0f372f..1c662f6 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -39,6 +39,7 @@
 #include <linux/smp.h>
 #include <linux/anon_inodes.h>
 #include <linux/profile.h>
+#include <linux/kvm_para.h>
 
 #include <asm/processor.h>
 #include <asm/msr.h>
@@ -1362,51 +1363,61 @@
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_halt);
 
-int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
+int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 {
-	unsigned long nr, a0, a1, a2, a3, a4, a5, ret;
+	unsigned long nr, a0, a1, a2, a3, ret;
 
 	kvm_x86_ops->cache_regs(vcpu);
-	ret = -KVM_EINVAL;
-#ifdef CONFIG_X86_64
-	if (is_long_mode(vcpu)) {
-		nr = vcpu->regs[VCPU_REGS_RAX];
-		a0 = vcpu->regs[VCPU_REGS_RDI];
-		a1 = vcpu->regs[VCPU_REGS_RSI];
-		a2 = vcpu->regs[VCPU_REGS_RDX];
-		a3 = vcpu->regs[VCPU_REGS_RCX];
-		a4 = vcpu->regs[VCPU_REGS_R8];
-		a5 = vcpu->regs[VCPU_REGS_R9];
-	} else
-#endif
-	{
-		nr = vcpu->regs[VCPU_REGS_RBX] & -1u;
-		a0 = vcpu->regs[VCPU_REGS_RAX] & -1u;
-		a1 = vcpu->regs[VCPU_REGS_RCX] & -1u;
-		a2 = vcpu->regs[VCPU_REGS_RDX] & -1u;
-		a3 = vcpu->regs[VCPU_REGS_RSI] & -1u;
-		a4 = vcpu->regs[VCPU_REGS_RDI] & -1u;
-		a5 = vcpu->regs[VCPU_REGS_RBP] & -1u;
+
+	nr = vcpu->regs[VCPU_REGS_RAX];
+	a0 = vcpu->regs[VCPU_REGS_RBX];
+	a1 = vcpu->regs[VCPU_REGS_RCX];
+	a2 = vcpu->regs[VCPU_REGS_RDX];
+	a3 = vcpu->regs[VCPU_REGS_RSI];
+
+	if (!is_long_mode(vcpu)) {
+		nr &= 0xFFFFFFFF;
+		a0 &= 0xFFFFFFFF;
+		a1 &= 0xFFFFFFFF;
+		a2 &= 0xFFFFFFFF;
+		a3 &= 0xFFFFFFFF;
 	}
+
 	switch (nr) {
 	default:
-		run->hypercall.nr = nr;
-		run->hypercall.args[0] = a0;
-		run->hypercall.args[1] = a1;
-		run->hypercall.args[2] = a2;
-		run->hypercall.args[3] = a3;
-		run->hypercall.args[4] = a4;
-		run->hypercall.args[5] = a5;
-		run->hypercall.ret = ret;
-		run->hypercall.longmode = is_long_mode(vcpu);
-		kvm_x86_ops->decache_regs(vcpu);
-		return 0;
+		ret = -KVM_ENOSYS;
+		break;
 	}
 	vcpu->regs[VCPU_REGS_RAX] = ret;
 	kvm_x86_ops->decache_regs(vcpu);
-	return 1;
+	return 0;
 }
-EXPORT_SYMBOL_GPL(kvm_hypercall);
+EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);
+
+int kvm_fix_hypercall(struct kvm_vcpu *vcpu)
+{
+	char instruction[3];
+	int ret = 0;
+
+	mutex_lock(&vcpu->kvm->lock);
+
+	/*
+	 * Blow out the MMU to ensure that no other VCPU has an active mapping
+	 * to ensure that the updated hypercall appears atomically across all
+	 * VCPUs.
+	 */
+	kvm_mmu_zap_all(vcpu->kvm);
+
+	kvm_x86_ops->cache_regs(vcpu);
+	kvm_x86_ops->patch_hypercall(vcpu, instruction);
+	if (emulator_write_emulated(vcpu->rip, instruction, 3, vcpu)
+	    != X86EMUL_CONTINUE)
+		ret = -EFAULT;
+
+	mutex_unlock(&vcpu->kvm->lock);
+
+	return ret;
+}
 
 static u64 mk_cr_64(u64 curr_cr, u32 new_val)
 {
@@ -1474,75 +1485,6 @@
 	}
 }
 
-/*
- * Register the para guest with the host:
- */
-static int vcpu_register_para(struct kvm_vcpu *vcpu, gpa_t para_state_gpa)
-{
-	struct kvm_vcpu_para_state *para_state;
-	hpa_t para_state_hpa, hypercall_hpa;
-	struct page *para_state_page;
-	unsigned char *hypercall;
-	gpa_t hypercall_gpa;
-
-	printk(KERN_DEBUG "kvm: guest trying to enter paravirtual mode\n");
-	printk(KERN_DEBUG ".... para_state_gpa: %08Lx\n", para_state_gpa);
-
-	/*
-	 * Needs to be page aligned:
-	 */
-	if (para_state_gpa != PAGE_ALIGN(para_state_gpa))
-		goto err_gp;
-
-	para_state_hpa = gpa_to_hpa(vcpu, para_state_gpa);
-	printk(KERN_DEBUG ".... para_state_hpa: %08Lx\n", para_state_hpa);
-	if (is_error_hpa(para_state_hpa))
-		goto err_gp;
-
-	mark_page_dirty(vcpu->kvm, para_state_gpa >> PAGE_SHIFT);
-	para_state_page = pfn_to_page(para_state_hpa >> PAGE_SHIFT);
-	para_state = kmap(para_state_page);
-
-	printk(KERN_DEBUG "....  guest version: %d\n", para_state->guest_version);
-	printk(KERN_DEBUG "....           size: %d\n", para_state->size);
-
-	para_state->host_version = KVM_PARA_API_VERSION;
-	/*
-	 * We cannot support guests that try to register themselves
-	 * with a newer API version than the host supports:
-	 */
-	if (para_state->guest_version > KVM_PARA_API_VERSION) {
-		para_state->ret = -KVM_EINVAL;
-		goto err_kunmap_skip;
-	}
-
-	hypercall_gpa = para_state->hypercall_gpa;
-	hypercall_hpa = gpa_to_hpa(vcpu, hypercall_gpa);
-	printk(KERN_DEBUG ".... hypercall_hpa: %08Lx\n", hypercall_hpa);
-	if (is_error_hpa(hypercall_hpa)) {
-		para_state->ret = -KVM_EINVAL;
-		goto err_kunmap_skip;
-	}
-
-	printk(KERN_DEBUG "kvm: para guest successfully registered.\n");
-	vcpu->para_state_page = para_state_page;
-	vcpu->para_state_gpa = para_state_gpa;
-	vcpu->hypercall_gpa = hypercall_gpa;
-
-	mark_page_dirty(vcpu->kvm, hypercall_gpa >> PAGE_SHIFT);
-	hypercall = kmap_atomic(pfn_to_page(hypercall_hpa >> PAGE_SHIFT),
-				KM_USER1) + (hypercall_hpa & ~PAGE_MASK);
-	kvm_x86_ops->patch_hypercall(vcpu, hypercall);
-	kunmap_atomic(hypercall, KM_USER1);
-
-	para_state->ret = 0;
-err_kunmap_skip:
-	kunmap(para_state_page);
-	return 0;
-err_gp:
-	return 1;
-}
-
 int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 {
 	u64 data;
@@ -1656,12 +1598,6 @@
 	case MSR_IA32_MISC_ENABLE:
 		vcpu->ia32_misc_enable_msr = data;
 		break;
-	/*
-	 * This is the 'probe whether the host is KVM' logic:
-	 */
-	case MSR_KVM_API_MAGIC:
-		return vcpu_register_para(vcpu, data);
-
 	default:
 		pr_unimpl(vcpu, "unhandled wrmsr: 0x%x\n", msr);
 		return 1;
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index ced4ac1..794d954 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -476,7 +476,8 @@
 					INTERCEPT_DR5_MASK |
 					INTERCEPT_DR7_MASK;
 
-	control->intercept_exceptions = 1 << PF_VECTOR;
+	control->intercept_exceptions = (1 << PF_VECTOR) |
+					(1 << UD_VECTOR);
 
 
 	control->intercept = 	(1ULL << INTERCEPT_INTR) |
@@ -979,6 +980,17 @@
 	return 0;
 }
 
+static int ud_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+	int er;
+
+	er = emulate_instruction(&svm->vcpu, kvm_run, 0, 0);
+	if (er != EMULATE_DONE)
+		inject_ud(&svm->vcpu);
+
+	return 1;
+}
+
 static int nm_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
 {
 	svm->vmcb->control.intercept_exceptions &= ~(1 << NM_VECTOR);
@@ -1045,7 +1057,8 @@
 {
 	svm->next_rip = svm->vmcb->save.rip + 3;
 	skip_emulated_instruction(&svm->vcpu);
-	return kvm_hypercall(&svm->vcpu, kvm_run);
+	kvm_emulate_hypercall(&svm->vcpu);
+	return 1;
 }
 
 static int invalid_op_interception(struct vcpu_svm *svm,
@@ -1241,6 +1254,7 @@
 	[SVM_EXIT_WRITE_DR3]			= emulate_on_interception,
 	[SVM_EXIT_WRITE_DR5]			= emulate_on_interception,
 	[SVM_EXIT_WRITE_DR7]			= emulate_on_interception,
+	[SVM_EXIT_EXCP_BASE + UD_VECTOR]	= ud_interception,
 	[SVM_EXIT_EXCP_BASE + PF_VECTOR] 	= pf_interception,
 	[SVM_EXIT_EXCP_BASE + NM_VECTOR] 	= nm_interception,
 	[SVM_EXIT_INTR] 			= nop_on_interception,
@@ -1675,7 +1689,6 @@
 	hypercall[0] = 0x0f;
 	hypercall[1] = 0x01;
 	hypercall[2] = 0xd9;
-	hypercall[3] = 0xc3;
 }
 
 static void svm_check_processor_compat(void *rtn)
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 5b397b6..47c827d 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -164,6 +164,13 @@
 		(INTR_TYPE_EXCEPTION | NM_VECTOR | INTR_INFO_VALID_MASK);
 }
 
+static inline int is_invalid_opcode(u32 intr_info)
+{
+	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
+			     INTR_INFO_VALID_MASK)) ==
+		(INTR_TYPE_EXCEPTION | UD_VECTOR | INTR_INFO_VALID_MASK);
+}
+
 static inline int is_external_interrupt(u32 intr_info)
 {
 	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
@@ -315,7 +322,7 @@
 {
 	u32 eb;
 
-	eb = 1u << PF_VECTOR;
+	eb = (1u << PF_VECTOR) | (1u << UD_VECTOR);
 	if (!vcpu->fpu_active)
 		eb |= 1u << NM_VECTOR;
 	if (vcpu->guest_debug.enabled)
@@ -560,6 +567,14 @@
 		     INTR_INFO_VALID_MASK);
 }
 
+static void vmx_inject_ud(struct kvm_vcpu *vcpu)
+{
+	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
+		     UD_VECTOR |
+		     INTR_TYPE_EXCEPTION |
+		     INTR_INFO_VALID_MASK);
+}
+
 /*
  * Swap MSR entry in host/guest MSR entry array.
  */
@@ -1771,6 +1786,14 @@
 		return 1;
 	}
 
+	if (is_invalid_opcode(intr_info)) {
+		er = emulate_instruction(vcpu, kvm_run, 0, 0);
+		if (er != EMULATE_DONE)
+			vmx_inject_ud(vcpu);
+
+		return 1;
+	}
+
 	error_code = 0;
 	rip = vmcs_readl(GUEST_RIP);
 	if (intr_info & INTR_INFO_DELIEVER_CODE_MASK)
@@ -1873,7 +1896,6 @@
 	hypercall[0] = 0x0f;
 	hypercall[1] = 0x01;
 	hypercall[2] = 0xc1;
-	hypercall[3] = 0xc3;
 }
 
 static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
@@ -2059,7 +2081,8 @@
 static int handle_vmcall(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	skip_emulated_instruction(vcpu);
-	return kvm_hypercall(vcpu, kvm_run);
+	kvm_emulate_hypercall(vcpu);
+	return 1;
 }
 
 /*
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 84af9cc..f12bc2c 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -1384,7 +1384,11 @@
 			if (modrm_mod != 3 || modrm_rm != 1)
 				goto cannot_emulate;
 
-			/* nop */
+			rc = kvm_fix_hypercall(ctxt->vcpu);
+			if (rc)
+				goto done;
+
+			kvm_emulate_hypercall(ctxt->vcpu);
 			break;
 		case 2: /* lgdt */
 			rc = read_descriptor(ctxt, ops, src.ptr,
@@ -1395,7 +1399,10 @@
 			break;
 		case 3: /* lidt/vmmcall */
 			if (modrm_mod == 3 && modrm_rm == 1) {
-				/* nop */
+				rc = kvm_fix_hypercall(ctxt->vcpu);
+				if (rc)
+					goto done;
+				kvm_emulate_hypercall(ctxt->vcpu);
 			} else {
 				rc = read_descriptor(ctxt, ops, src.ptr,
 						     &size, &address,
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 3b29256..cc5dfb43 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -1,73 +1,110 @@
 #ifndef __LINUX_KVM_PARA_H
 #define __LINUX_KVM_PARA_H
 
-/*
- * Guest OS interface for KVM paravirtualization
+/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
+ * should be used to determine that a VM is running under KVM.
+ */
+#define KVM_CPUID_SIGNATURE	0x40000000
+
+/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
+ * paravirtualization, the appropriate feature bit should be checked.
+ */
+#define KVM_CPUID_FEATURES	0x40000001
+
+/* Return values for hypercalls */
+#define KVM_ENOSYS		1000
+
+#ifdef __KERNEL__
+#include <asm/processor.h>
+
+/* This instruction is vmcall.  On non-VT architectures, it will generate a
+ * trap that we will then rewrite to the appropriate instruction.
+ */
+#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
+
+/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
+ * instruction.  The hypervisor may replace it with something else but only the
+ * instructions are guaranteed to be supported.
  *
- * Note: this interface is totally experimental, and is certain to change
- *       as we make progress.
+ * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
+ * The hypercall number should be placed in rax and the return value will be
+ * placed in rax.  No other registers will be clobbered unless explicited
+ * noted by the particular hypercall.
  */
 
-/*
- * Per-VCPU descriptor area shared between guest and host. Writable to
- * both guest and host. Registered with the host by the guest when
- * a guest acknowledges paravirtual mode.
- *
- * NOTE: all addresses are guest-physical addresses (gpa), to make it
- * easier for the hypervisor to map between the various addresses.
- */
-struct kvm_vcpu_para_state {
-	/*
-	 * API version information for compatibility. If there's any support
-	 * mismatch (too old host trying to execute too new guest) then
-	 * the host will deny entry into paravirtual mode. Any other
-	 * combination (new host + old guest and new host + new guest)
-	 * is supposed to work - new host versions will support all old
-	 * guest API versions.
-	 */
-	u32 guest_version;
-	u32 host_version;
-	u32 size;
-	u32 ret;
+static inline long kvm_hypercall0(unsigned int nr)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr));
+	return ret;
+}
 
-	/*
-	 * The address of the vm exit instruction (VMCALL or VMMCALL),
-	 * which the host will patch according to the CPU model the
-	 * VM runs on:
-	 */
-	u64 hypercall_gpa;
+static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1));
+	return ret;
+}
 
-} __attribute__ ((aligned(PAGE_SIZE)));
+static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
+				  unsigned long p2)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2));
+	return ret;
+}
 
-#define KVM_PARA_API_VERSION 1
+static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
+	return ret;
+}
 
-/*
- * This is used for an RDMSR's ECX parameter to probe for a KVM host.
- * Hopefully no CPU vendor will use up this number. This is placed well
- * out of way of the typical space occupied by CPU vendors' MSR indices,
- * and we think (or at least hope) it wont be occupied in the future
- * either.
- */
-#define MSR_KVM_API_MAGIC 0x87655678
+static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3,
+				  unsigned long p4)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
+	return ret;
+}
 
-#define KVM_EINVAL 1
+static inline int kvm_para_available(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+	char signature[13];
 
-/*
- * Hypercall calling convention:
- *
- * Each hypercall may have 0-6 parameters.
- *
- * 64-bit hypercall index is in RAX, goes from 0 to __NR_hypercalls-1
- *
- * 64-bit parameters 1-6 are in the standard gcc x86_64 calling convention
- * order: RDI, RSI, RDX, RCX, R8, R9.
- *
- * 32-bit index is EBX, parameters are: EAX, ECX, EDX, ESI, EDI, EBP.
- * (the first 3 are according to the gcc regparm calling convention)
- *
- * No registers are clobbered by the hypercall, except that the
- * return value is in RAX.
- */
-#define __NR_hypercalls			0
+	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
+	memcpy(signature + 0, &ebx, 4);
+	memcpy(signature + 4, &ecx, 4);
+	memcpy(signature + 8, &edx, 4);
+	signature[12] = 0;
+
+	if (strcmp(signature, "KVMKVMKVM") == 0)
+		return 1;
+
+	return 0;
+}
+
+static inline int kvm_para_has_feature(unsigned int feature)
+{
+	if (cpuid_eax(KVM_CPUID_FEATURES) & (1UL << feature))
+		return 1;
+	return 0;
+}
+
+#endif
 
 #endif