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Groups > linux.kernel > #1526236
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle |
| Date | 2016-11-20 14:20 +0100 |
| Message-ID | <sFAci-2Z1-9@gated-at.bofh.it> (permalink) |
| References | <sFelr-5AY-3@gated-at.bofh.it> <sFelr-5AY-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Sat, Nov 19, 2016 at 01:47:37PM -0000, Thomas Gleixner wrote:
> When entering idle, it's a good oportunity to verify that the TSC_ADJUST
> MSR has not been tampered with (BIOS hiding SMM cycles). If tampering is
> detected, emit a warning and restore it to the previous value.
> +++ b/arch/x86/kernel/process.c
> @@ -277,6 +277,7 @@ void exit_idle(void)
>
> void arch_cpu_idle_enter(void)
> {
> + tsc_verify_tsc_adjust();
> local_touch_nmi();
> enter_idle();
> }
Doing a RDMSR on the idle path isn't going to be popular. That path is
already way too slow.
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[patch 0/8] x86/tsc: Utilize TSC_ADJUST MSR Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
[patch 4/8] x86/tsc: Verify TSC_ADJUST from idle Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
Re: [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle Peter Zijlstra <peterz@infradead.org> - 2016-11-20 14:20 +0100
Re: [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle Thomas Gleixner <tglx@linutronix.de> - 2016-11-21 09:20 +0100
Re: [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle Peter Zijlstra <peterz@infradead.org> - 2016-11-21 12:10 +0100
Re: [patch 4/8] x86/tsc: Verify TSC_ADJUST from idle Andi Kleen <andi@firstfloor.org> - 2016-11-22 00:00 +0100
[patch 5/8] x86/tsc: Sync test only for the first cpu in a package Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
[patch 3/8] x86/tsc: Store and check TSC ADJUST MSR Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
[patch 1/8] x86/tsc: Use X86_FEATURE_TSC_ADJUST in detect_art() Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
[patch 2/8] x86/tsc: Detect random warps Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
[patch 7/8] x86/tsc: Prepare warp test for TSC adjustment Thomas Gleixner <tglx@linutronix.de> - 2016-11-19 15:00 +0100
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