KVM: x86: Don't check kvm_rebooting in __kvm_handle_fault_on_reboot()

Remove the kvm_rebooting check from VMX/SVM instruction exception fixup
now that kvm_spurious_fault() conditions its BUG() on !kvm_rebooting.
Because the 'cleanup_insn' functionally is also gone, deferring to
kvm_spurious_fault() means __kvm_handle_fault_on_reboot() can eliminate
its .fixup code entirely and have its exception table entry branch
directly to the call to kvm_spurious_fault().

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1549,13 +1549,7 @@ asmlinkage void kvm_spurious_fault(void);
 	"667: \n\t"							\
 	"call	kvm_spurious_fault \n\t"				\
 	"668: \n\t"							\
-	".pushsection .fixup, \"ax\" \n\t"				\
-	"700: \n\t"							\
-	"cmpb	$0, kvm_rebooting\n\t"					\
-	"je	667b \n\t"						\
-	"jmp	668b \n\t"						\
-	".popsection \n\t"						\
-	_ASM_EXTABLE(666b, 700b)
+	_ASM_EXTABLE(666b, 667b)
 
 #define KVM_ARCH_WANT_MMU_NOTIFIER
 int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end);