KVM: fix exception entry / build bug, on 64-bit

-tip testing found this build bug:

 arch/x86/kvm/built-in.o:(.text.fixup+0x1): relocation truncated to fit: R_X86_64_32 against `.text'
 arch/x86/kvm/built-in.o:(.text.fixup+0xb): relocation truncated to fit: R_X86_64_32 against `.text'
 arch/x86/kvm/built-in.o:(.text.fixup+0x15): relocation truncated to fit: R_X86_64_32 against `.text'
 arch/x86/kvm/built-in.o:(.text.fixup+0x1f): relocation truncated to fit: R_X86_64_32 against `.text'
 arch/x86/kvm/built-in.o:(.text.fixup+0x29): relocation truncated to fit: R_X86_64_32 against `.text'

Introduced by commit 4ecac3fd. The problem is that 'push' will default
to 32-bit, which is not wide enough as a fixup address. (and which would
crash on any real fixup event even if it was wide enough)

Introduce KVM_EX_PUSH to get the proper address push width on 64-bit too.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/asm-x86/kvm_host.h

@@ -703,9 +703,11 @@ enum {
 						vcpu, 0, 0, 0, 0, 0, 0)
 
 #ifdef CONFIG_64BIT
-#define KVM_EX_ENTRY ".quad"
+# define KVM_EX_ENTRY ".quad"
+# define KVM_EX_PUSH "pushq"
 #else
-#define KVM_EX_ENTRY ".long"
+# define KVM_EX_ENTRY ".long"
+# define KVM_EX_PUSH "pushl"
 #endif
 
 /*
@@ -719,7 +721,7 @@ asmlinkage void kvm_handle_fault_on_reboot(void);
 	"666: " insn "\n\t" \
 	".pushsection .text.fixup, \"ax\" \n" \
 	"667: \n\t" \
-	"push $666b \n\t" \
+	KVM_EX_PUSH " $666b \n\t" \
 	"jmp kvm_handle_fault_on_reboot \n\t" \
 	".popsection \n\t" \
 	".pushsection __ex_table, \"a\" \n\t" \