File 5fedf9f4-x86-hpet_setup-fix-retval.patch of Package xen

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File 5fedf9f4-x86-hpet_setup-fix-retval.patch of Package xen

# Commit 83736c567d6b64dbce98f251ca72e7870f556421
# Date 2020-12-31 16:19:00 +0000
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
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@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

--- 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)

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File 5fedf9f4-x86-hpet_setup-fix-retval.patch of Package xen

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