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

Impact: prepare the hpet code for Xen dom0 booting

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>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 84089dc8fd1d..a1f6ed5e1a05 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -834,10 +834,11 @@ static __init int hpet_late_init(void)
 
                 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));
 
         for_each_online_cpu(cpu) {