Commit 6a369583 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/tsc: Validate TSC_ADJUST after resume 



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-and-tested-by: default avatarRoland Scheidegger <rscheidegger_lists@hispeed.ch>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Bruce Schlobohm <bruce.schlobohm@intel.com>
Cc: Kevin Stanton <kevin.b.stanton@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Allen Hung <allen_hung@dell.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20161213131211.317654500@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 31f8a651

arch/x86/include/asm/tsc.h

+2 −2
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -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();

}

arch/x86/kernel/tsc.c

+6 −0
Original line number Diff line number Diff line
@@ -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_tsc = { 
	.flags                  = CLOCK_SOURCE_IS_CONTINUOUS |

				  CLOCK_SOURCE_MUST_VERIFY,

	.archdata               = { .vclock_mode = VCLOCK_TSC },

	.resume			= tsc_resume,

};



void mark_tsc_unstable(char *reason)

arch/x86/kernel/tsc_sync.c

+3 −3
Original line number Diff line number Diff line
@@ -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;

arch/x86/power/cpu.c

+1 −0
Original line number Diff line number Diff line
@@ -252,6 +252,7 @@ static void notrace __restore_processor_state(struct saved_context *ctxt) 
	fix_processor_context();



	do_fpu_end();

	tsc_verify_tsc_adjust(true);

	x86_platform.restore_sched_clock_state();

	mtrr_bp_restore();

	perf_restore_debug_store();

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