[xen stable-4.14] x86/hpet: Fix return value of hpet_setup()

[patchbot@xxxxxxx]

commit a514c5ef5bda0da4020b22037d921b845a151116
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Jan 21 16:17:21 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Jan 21 16:17:21 2021 +0100

    x86/hpet: Fix return value of hpet_setup()
    
    hpet_setup() is idempotent if the rate has already been calculated, and
    returns the cached value.  However, this only works correctly when the 
return
    statements are identical.
    
    Use a sensibly named local variable, rather than a dead one with a bad name.
    
    Fixes: a60bb68219 ("x86/time: reduce rounding errors in calculations")
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    master commit: 83736c567d6b64dbce98f251ca72e7870f556421
    master date: 2020-12-31 16:19:00 +0000
---
 xen/arch/x86/hpet.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hpet.c b/xen/arch/x86/hpet.c
index 154c67423b..f4951d7a20 100644
--- a/xen/arch/x86/hpet.c
+++ b/xen/arch/x86/hpet.c
@@ -769,7 +769,7 @@ u64 __init hpet_setup(void)
 {
     static u64 __initdata hpet_rate;
     u32 hpet_id, hpet_period;
-    unsigned int last;
+    unsigned int last, rem;
 
     if ( hpet_rate )
         return hpet_rate;
@@ -799,9 +799,11 @@ u64 __init hpet_setup(void)
     hpet_resume(hpet_boot_cfg);
 
     hpet_rate = 1000000000000000ULL; /* 10^15 */
-    last = do_div(hpet_rate, hpet_period);
+    rem = do_div(hpet_rate, hpet_period);
+    if ( (rem * 2) > hpet_period )
+        hpet_rate++;
 
-    return hpet_rate + (last * 2 > hpet_period);
+    return hpet_rate;
 }
 
 void hpet_resume(u32 *boot_cfg)
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.14