[PATCH] x86: make sure we really have an hpet mapping before using it

[Jeremy Fitzhardinge <jeremy@goop.org>]

When booting in Xen dom0, the hpet isn't really accessible, so make
sure the mapping is non-NULL before use.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 arch/x86/kernel/hpet.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

===================================================================
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -818,9 +818,10 @@
 
 		hpet_address = force_hpet_address;
 		hpet_enable();
-		if (!hpet_virt_address)
-			return -ENODEV;
 	}
+
+	if (!hpet_virt_address)
+		return -ENODEV;
 
 	hpet_reserve_platform_timers(hpet_readl(HPET_ID));