From 8180a550284bf2c8e13414082fc20b8983c2c401 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 21 Jul 2007 17:10:07 +0200 Subject: [PATCH] x86_64: hpet tsc calibration fix broken smi detection logic The current SMI detection logic in read_hpet_tsc() makes sure, that when a SMI happens between the read of the HPET counter and the read of the TSC, this wrong value is used for TSC calibration. This is not the intention of the function. The comparison must ensure, that we do _NOT_ use such a value. Fix the check to use calibration values where delta of the two TSC reads is smaller than a reasonable threshold. Signed-off-by: Thomas Gleixner Signed-off-by: Chris Wright Signed-off-by: Ingo Molnar Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/hpet.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86_64/kernel/hpet.c b/arch/x86_64/kernel/hpet.c index b8286968662d..6b460402d504 100644 --- a/arch/x86_64/kernel/hpet.c +++ b/arch/x86_64/kernel/hpet.c @@ -190,7 +190,7 @@ int hpet_reenable(void) */ #define TICK_COUNT 100000000 -#define TICK_MIN 5000 +#define SMI_THRESHOLD 50000 #define MAX_TRIES 5 /* @@ -205,7 +205,7 @@ static void __init read_hpet_tsc(int *hpet, int *tsc) tsc1 = get_cycles_sync(); hpet1 = hpet_readl(HPET_COUNTER); tsc2 = get_cycles_sync(); - if (tsc2 - tsc1 > TICK_MIN) + if ((tsc2 - tsc1) < SMI_THRESHOLD) break; } *hpet = hpet1; -- 2.30.2