x86/virt: Eat faults on VMXOFF in reboot flows

[linux-2.6-microblaze.git] / arch / x86 / include / asm / virtext.h

diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
index 9aad0e0..fda3e77 100644 (file)
--- a/arch/x86/include/asm/virtext.h
+++ b/arch/x86/include/asm/virtext.h
@@ -30,15 +30,22 @@ static inline int cpu_has_vmx(void)
 }
 
 
-/** Disable VMX on the current CPU
+/**
+ * cpu_vmxoff() - Disable VMX on the current CPU
  *
- * vmxoff causes a undefined-opcode exception if vmxon was not run
- * on the CPU previously. Only call this function if you know VMX
- * is enabled.
+ * Disable VMX and clear CR4.VMXE (even if VMXOFF faults)
+ *
+ * Note, VMXOFF causes a #UD if the CPU is !post-VMXON, but it's impossible to
+ * atomically track post-VMXON state, e.g. this may be called in NMI context.
+ * Eat all faults as all other faults on VMXOFF faults are mode related, i.e.
+ * faults are guaranteed to be due to the !post-VMXON check unless the CPU is
+ * magically in RM, VM86, compat mode, or at CPL>0.
  */
 static inline void cpu_vmxoff(void)
 {
-       asm volatile ("vmxoff");
+       asm_volatile_goto("1: vmxoff\n\t"
+                         _ASM_EXTABLE(1b, %l[fault]) :::: fault);
+fault:
        cr4_clear_bits(X86_CR4_VMXE);
 }