linux-kernel - Re: [patch 1/2] x86/tsc: Validate TSC

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Date:   Tue, 13 Dec 2016 14:22:50 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Borislav Petkov <bp@...en8.de>,
        Bruce Schlobohm <bruce.schlobohm@...el.com>,
        Roland Scheidegger <rscheidegger_lists@...peed.ch>,
        Kevin Stanton <kevin.b.stanton@...el.com>,
        Allen Hung <allen_hung@...l.com>
Subject: Re: [patch 1/2] x86/tsc: Validate TSC_ADJUST after resume

On Tue, Dec 13, 2016 at 01:14:17PM -0000, Thomas Gleixner wrote:
> --- 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);
>  }

Should we do that sooner, as in before calling
restore_sched_clock_state() ? Otherwise we recompute the sched_clock
deltas vs the wrecked TSC and then fix it up through the ADJUST,
wrecking our sched clock again.