diff -r 59b8768d0d0d xen/arch/x86/hvm/svm/emulate.c
--- a/xen/arch/x86/hvm/svm/emulate.c	Wed Mar 05 11:18:25 2008 +0000
+++ b/xen/arch/x86/hvm/svm/emulate.c	Mon Mar 10 13:05:14 2008 +0000
@@ -117,7 +117,9 @@ int __get_instruction_length_from_list(s
     }
     else
     {
-        inst_copy_from_guest(buffer, svm_rip2pointer(v), MAX_INST_LEN);
+        if ( inst_copy_from_guest(buffer, svm_rip2pointer(v), MAX_INST_LEN)
+             != MAX_INST_LEN )
+            return 0;
         buf = buffer;
     }
 
diff -r 59b8768d0d0d xen/arch/x86/hvm/svm/svm.c
--- a/xen/arch/x86/hvm/svm/svm.c	Wed Mar 05 11:18:25 2008 +0000
+++ b/xen/arch/x86/hvm/svm/svm.c	Mon Mar 10 13:09:45 2008 +0000
@@ -943,6 +943,10 @@ static void svm_vmexit_do_cpuid(struct c
 {
     unsigned int eax, ebx, ecx, edx, inst_len;
 
+    inst_len = __get_instruction_length(current, INSTR_CPUID, NULL);
+    if ( inst_len == 0 ) 
+        return;
+
     eax = regs->eax;
     ebx = regs->ebx;
     ecx = regs->ecx;
@@ -955,7 +959,6 @@ static void svm_vmexit_do_cpuid(struct c
     regs->ecx = ecx;
     regs->edx = edx;
 
-    inst_len = __get_instruction_length(current, INSTR_CPUID, NULL);
     __update_guest_eip(regs, inst_len);
 }
 
@@ -1166,6 +1169,8 @@ static void svm_vmexit_do_hlt(struct vmc
     unsigned int inst_len;
 
     inst_len = __get_instruction_length(curr, INSTR_HLT, NULL);
+    if ( inst_len == 0 )
+        return 0;
     __update_guest_eip(regs, inst_len);
 
     /* Check for pending exception or new interrupt. */
@@ -1354,6 +1359,8 @@ asmlinkage void svm_vmexit_handler(struc
 
     case VMEXIT_VMMCALL:
         inst_len = __get_instruction_length(v, INSTR_VMCALL, NULL);
+        if ( inst_len == 0 )
+            break;
         HVMTRACE_1D(VMMCALL, v, regs->eax);
         rc = hvm_do_hypercall(regs);
         if ( rc != HVM_HCALL_preempted )