vmx: Do not set bit 1 of FEATURE_CONTROL MSR if SMX is not supported

by the CPU. Also generally beef up robustness of VMXON instruction.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

3 files changed, 29 insertions, 21 deletions

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 1cb1746516..4ecbccef66 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -274,19 +274,13 @@ int vmx_cpu_up(void)
     }
     else
     {
-        eax = (IA32_FEATURE_CONTROL_MSR_LOCK |
-               IA32_FEATURE_CONTROL_MSR_ENABLE_VMXON_OUTSIDE_SMX |
-               IA32_FEATURE_CONTROL_MSR_ENABLE_VMXON_INSIDE_SMX);
+        eax  = IA32_FEATURE_CONTROL_MSR_LOCK;
+        eax |= IA32_FEATURE_CONTROL_MSR_ENABLE_VMXON_OUTSIDE_SMX;
+        if ( test_bit(X86_FEATURE_SMXE, &boot_cpu_data.x86_capability) )
+            eax |= IA32_FEATURE_CONTROL_MSR_ENABLE_VMXON_INSIDE_SMX;
         wrmsr(IA32_FEATURE_CONTROL_MSR, eax, 0);
     }
 
-    if ( !tboot_in_measured_env() &&
-         !(eax & IA32_FEATURE_CONTROL_MSR_ENABLE_VMXON_OUTSIDE_SMX) )
-    {
-        printk("VMX only allowed in SMX but SMX not active.\n");
-        return 0;
-    }
-
     vmx_init_vmcs_config();
 
     INIT_LIST_HEAD(&this_cpu(active_vmcs_list));
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index d814e296aa..e8aa866239 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -719,6 +719,7 @@ asmlinkage void do_invalid_op(struct cpu_user_regs *regs)
     struct bug_frame bug;
     struct bug_frame_str bug_str;
     char *filename, *predicate, *eip = (char *)regs->eip;
+    unsigned long fixup;
     int id, lineno;
 
     DEBUGGER_trap_entry(TRAP_invalid_op, regs);
@@ -789,6 +790,11 @@ asmlinkage void do_invalid_op(struct cpu_user_regs *regs)
           predicate, filename, lineno);
 
  die:
+    if ( (fixup = search_exception_table(regs->eip)) != 0 )
+    {
+        regs->eip = fixup;
+        return;
+    }
     DEBUGGER_trap_fatal(TRAP_invalid_op, regs);
     show_execution_state(regs);
     panic("FATAL TRAP: vector = %d (invalid opcode)\n", TRAP_invalid_op);
diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h b/xen/include/asm-x86/hvm/vmx/vmx.h
index be6e2d7429..af50427ed3 100644
--- a/xen/include/asm-x86/hvm/vmx/vmx.h
+++ b/xen/include/asm-x86/hvm/vmx/vmx.h
@@ -240,23 +240,31 @@ static inline void __vm_clear_bit(unsigned long field, unsigned int bit)
     __vmwrite(field, __vmread(field) & ~(1UL << bit));
 }
 
-static inline void __vmxoff (void)
+static inline void __vmxoff(void)
 {
-    __asm__ __volatile__ ( VMXOFF_OPCODE
-                           ::: "memory");
+    asm volatile (
+        VMXOFF_OPCODE
+        : : : "memory" );
 }
 
-static inline int __vmxon (u64 addr)
+static inline int __vmxon(u64 addr)
 {
     int rc;
 
-    __asm__ __volatile__ ( VMXON_OPCODE
-                           MODRM_EAX_06
-                           /* CF==1 or ZF==1 --> rc = -1 */
-                           "setna %b0 ; neg %0"
-                           : "=q" (rc)
-                           : "0" (0), "a" (&addr)
-                           : "memory");
+    asm volatile ( 
+        "1: " VMXON_OPCODE MODRM_EAX_06 "\n"
+        "   setna %b0 ; neg %0\n" /* CF==1 or ZF==1 --> rc = -1 */
+        "2:\n"
+        ".section .fixup,\"ax\"\n"
+        "3: not %0 ; jmp 2b\n"    /* #UD --> rc = -1 */
+        ".previous\n"
+        ".section __ex_table,\"a\"\n"
+        "   "__FIXUP_ALIGN"\n"
+        "   "__FIXUP_WORD" 1b,3b\n"
+        ".previous\n"
+        : "=q" (rc)
+        : "0" (0), "a" (&addr)
+        : "memory");
 
     return rc;
 }