Commit-ID: 81ffdcdd97d94110627caa81c23d5d780083731d Gitweb: http://git.kernel.org/tip/81ffdcdd97d94110627caa81c23d5d780083731d Author: Andi Kleen <[email protected]> AuthorDate: Mon, 19 Oct 2015 11:17:48 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 21 Oct 2015 11:10:57 +0200
x86/mce: Fix thermal throttling reporting after kexec The per CPU thermal vector init code checks if the thermal vector is already installed and complains and bails out if it is. This happens after kexec, as kernel shut down does not clear the thermal vector APIC register. This causes two problems: 1. So we always do not fully initialize thermal reports after kexec. The CPU is still likely initialized, as the previous kernel should have done it. But we don't set up the software pointer to the thermal vector, so reporting may end up with a unknown thermal interrupt message. 2. Also it complains for every logical CPU, even though the value is actually derived from BP only. The problem is that we end up with one message per CPU, so on larger systems it becomes very noisy and messes up the otherwise nicely formatted CPU bootup numbers in the kernel log. Just remove the check. I checked the code and there's no valid code paths where the thermal init code for a CPU could be called multiple times. Why the kernel does not clean up this value on shutdown: The thermal monitoring is controlled per logical CPU thread. Normal shutdown code is just running on one CPU. To disable it we would need a broadcast NMI to all CPUs on shut down. That's overkill for this. So we just ignore it after kexec. Signed-off-by: Andi Kleen <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Tony Luck <[email protected]> Cc: linux-edac <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/cpu/mcheck/therm_throt.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c index 1af51b1..2c5aaf8 100644 --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c @@ -503,14 +503,6 @@ void intel_init_thermal(struct cpuinfo_x86 *c) return; } - /* Check whether a vector already exists */ - if (h & APIC_VECTOR_MASK) { - printk(KERN_DEBUG - "CPU%d: Thermal LVT vector (%#x) already installed\n", - cpu, (h & APIC_VECTOR_MASK)); - return; - } - /* early Pentium M models use different method for enabling TM2 */ if (cpu_has(c, X86_FEATURE_TM2)) { if (c->x86 == 6 && (c->x86_model == 9 || c->x86_model == 13)) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
