diff options
| author |   Chen Yu <yu.c.chen@intel.com> | 2016-05-06 11:33:39 +0800 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2016-05-06 11:50:50 +0200 |
| commit | 886123fb3a8656699dff40afa0573df359abeb18 (patch) | |
| tree | f3bf6d9ad49babf098f3f3142a34d79d1744b848 /arch | |
| parent | x86/platform/UV: Bring back the call to map_low_mmrs in uv_system_init (diff) | |
| download | linux-dev-886123fb3a8656699dff40afa0573df359abeb18.tar.xz linux-dev-886123fb3a8656699dff40afa0573df359abeb18.zip | |
x86/tsc: Read all ratio bits from MSR_PLATFORM_INFO
Currently we read the tsc radio: ratio = (MSR_PLATFORM_INFO >> 8) & 0x1f;
Thus we get bit 8-12 of MSR_PLATFORM_INFO, however according to the SDM
(35.5), the ratio bits are bit 8-15.
Ignoring the upper bits can result in an incorrect tsc ratio, which causes the
TSC calibration and the Local APIC timer frequency to be incorrect.
Fix this problem by masking 0xff instead.
[ tglx: Massaged changelog ]
Fixes: 7da7c1561366 "x86, tsc: Add static (MSR) TSC calibration on Intel Atom SoCs"
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: stable@vger.kernel.org
Cc: Bin Gao <bin.gao@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/1462505619-5516-1-git-send-email-yu.c.chen@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/tsc_msr.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c index 92ae6acac8a7..6aa0f4d9eea6 100644 --- a/arch/x86/kernel/tsc_msr.c +++ b/arch/x86/kernel/tsc_msr.c @@ -92,7 +92,7 @@ unsigned long try_msr_calibrate_tsc(void) if (freq_desc_tables[cpu_index].msr_plat) { rdmsr(MSR_PLATFORM_INFO, lo, hi); - ratio = (lo >> 8) & 0x1f; + ratio = (lo >> 8) & 0xff; } else { rdmsr(MSR_IA32_PERF_STATUS, lo, hi); ratio = (hi >> 8) & 0x1f; |