From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753565AbcLMNRI (ORCPT ); Tue, 13 Dec 2016 08:17:08 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:41528 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221AbcLMNRG (ORCPT ); Tue, 13 Dec 2016 08:17:06 -0500 Message-Id: <20161213131211.317654500@linutronix.de> User-Agent: quilt/0.63-1 Date: Tue, 13 Dec 2016 13:14:17 -0000 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Peter Zijlstra , Borislav Petkov , Bruce Schlobohm , Roland Scheidegger , Kevin Stanton , Allen Hung Subject: [patch 1/2] x86/tsc: Validate TSC_ADJUST after resume References: <20161213131115.764824574@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86-tsc--Validate-TSC_ADJUST-after-resume.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some 'feature' BIOSes fiddle with the TSC_ADJUST register during suspend/resume which renders the TSC unusable. Add sanity checks into the resume path and restore the original value if it was adjusted. Reported-by: Roland Scheidegger Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/tsc.h | 4 ++-- arch/x86/kernel/process.c | 2 +- arch/x86/kernel/tsc.c | 6 ++++++ arch/x86/kernel/tsc_sync.c | 6 +++--- arch/x86/power/cpu.c | 1 + 5 files changed, 13 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -47,12 +47,12 @@ extern int tsc_clocksource_reliable; */ #ifdef CONFIG_X86_TSC extern bool tsc_store_and_check_tsc_adjust(void); -extern void tsc_verify_tsc_adjust(void); +extern void tsc_verify_tsc_adjust(bool resume); extern void check_tsc_sync_source(int cpu); extern void check_tsc_sync_target(void); #else static inline bool tsc_store_and_check_tsc_adjust(void) { return false; } -static inline void tsc_verify_tsc_adjust(void) { } +static inline void tsc_verify_tsc_adjust(bool resume) { } static inline void check_tsc_sync_source(int cpu) { } static inline void check_tsc_sync_target(void) { } #endif --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -277,7 +277,7 @@ void exit_idle(void) void arch_cpu_idle_enter(void) { - tsc_verify_tsc_adjust(); + tsc_verify_tsc_adjust(false); local_touch_nmi(); enter_idle(); } --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1080,6 +1080,11 @@ static void detect_art(void) static struct clocksource clocksource_tsc; +static void tsc_resume(struct clocksource *cs) +{ + tsc_verify_tsc_adjust(true); +} + /* * We used to compare the TSC to the cycle_last value in the clocksource * structure to avoid a nasty time-warp. This can be observed in a @@ -1112,6 +1117,7 @@ static struct clocksource clocksource_ts .flags = CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_MUST_VERIFY, .archdata = { .vclock_mode = VCLOCK_TSC }, + .resume = tsc_resume, }; void mark_tsc_unstable(char *reason) --- a/arch/x86/kernel/tsc_sync.c +++ b/arch/x86/kernel/tsc_sync.c @@ -30,7 +30,7 @@ struct tsc_adjust { static DEFINE_PER_CPU(struct tsc_adjust, tsc_adjust); -void tsc_verify_tsc_adjust(void) +void tsc_verify_tsc_adjust(bool resume) { struct tsc_adjust *adj = this_cpu_ptr(&tsc_adjust); s64 curval; @@ -39,7 +39,7 @@ void tsc_verify_tsc_adjust(void) return; /* Rate limit the MSR check */ - if (time_before(jiffies, adj->nextcheck)) + if (!resume && time_before(jiffies, adj->nextcheck)) return; adj->nextcheck = jiffies + HZ; @@ -51,7 +51,7 @@ void tsc_verify_tsc_adjust(void) /* Restore the original value */ wrmsrl(MSR_IA32_TSC_ADJUST, adj->adjusted); - if (!adj->warned) { + if (!adj->warned || resume) { pr_warn(FW_BUG "TSC ADJUST differs: CPU%u %lld --> %lld. Restoring\n", smp_processor_id(), adj->adjusted, curval); adj->warned = true; --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -256,6 +256,7 @@ static void notrace __restore_processor_ mtrr_bp_restore(); perf_restore_debug_store(); msr_restore_context(ctxt); + tsc_verify_tsc_adjust(true); } /* Needed by apm.c */