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From: Borislav Petkov <bp@suse.de>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH v7 04/10] TAAv7 4
Date: Wed, 23 Oct 2019 00:05:55 +0200	[thread overview]
Message-ID: <20191022220555.GZ31458@zn.tnic> (raw)
In-Reply-To: <20191022215321.GY31458@zn.tnic>

On Tue, Oct 22, 2019 at 11:53:21PM +0200, Borislav Petkov wrote:
> On Tue, Oct 22, 2019 at 02:29:02PM -0700, speck for Pawan Gupta wrote:
> > Side effect of RTM check ahead of X86_BUG_TAA will be a dmesg print
> > "Mitigation: TSX disabled" when X86_BUG_TAA is not set.
> 
> So what you're trying to tell me is that you don't want to print that
> message at all?
> 
> 	if (!boot_cpu_has(X86_FEATURE_RTM)) {
> 		taa_mitigation = TAA_MITIGATION_TSX_DISABLE;
> 		return;
> 	}
> 
> How's that?

And to perhaps answer your other question from below maybe - I'm
assuming you want something like this:

	if (!boot_cpu_has(X86_FEATURE_RTM)) {
		taa_mitigation = TAA_MITIGATION_TSX_DISABLE;
		setup_clear_cpu_bug(X86_BUG_TAA);
		return;
	}

This is assuming X86_FEATURE_RTM really mirrors the CPUID bit. And that
should be the case since if you do tsx_disable(), it will clear the
CPUID bit through the MSR. IOW, when TSX is disabled, you're basically
not affected by TAA, of course.

> > > Also, from all the possible settings:
> > > 
> > >         [TAA_MITIGATION_OFF]            = "Vulnerable",
> > >         [TAA_MITIGATION_UCODE_NEEDED]   = "Vulnerable: Clear CPU buffers attempted, no microcode",
> > >         [TAA_MITIGATION_VERW]           = "Mitigation: Clear CPU buffers",
> > >         [TAA_MITIGATION_TSX_DISABLE]    = "Mitigation: TSX disabled",
> > > 
> > > TAA_MITIGATION_TSX_DISABLE is the one that fits best for the !RTM case,
> > > no?
> > 
> > When X86_BUG_TAA is not set sysfs shows "Not affected" irrespective of
> > value of taa_mitigation.
> > 
> > 	cpu_show_common()
> > 	{
> > 		if (!boot_cpu_has_bug(bug))
> > 			return sprintf(buf, "Not affected\n");
> > 		[...]
> 
> Sorry, I can't follow what you're trying to tell me here.

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg

  reply	other threads:[~2019-10-22 22:06 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-21 20:22 [MODERATED] [PATCH v7 00/10] TAAv7 0 Pawan Gupta
2019-10-21 20:23 ` [MODERATED] [PATCH v7 01/10] TAAv7 1 Pawan Gupta
2019-10-21 20:24 ` [MODERATED] [PATCH v7 02/10] TAAv7 2 Pawan Gupta
2019-10-21 20:25 ` [MODERATED] [PATCH v7 03/10] TAAv7 3 Pawan Gupta
2019-10-21 20:26 ` [MODERATED] [PATCH v7 04/10] TAAv7 4 Pawan Gupta
2019-10-21 20:27 ` [MODERATED] [PATCH v7 05/10] TAAv7 5 Pawan Gupta
2019-10-21 20:28 ` [MODERATED] [PATCH v7 06/10] TAAv7 6 Pawan Gupta
2019-10-21 20:29 ` [MODERATED] [PATCH v7 07/10] TAAv7 7 Pawan Gupta
2019-10-21 20:30 ` [MODERATED] [PATCH v7 08/10] TAAv7 8 Pawan Gupta
2019-10-21 20:31 ` [MODERATED] [PATCH v7 09/10] TAAv7 9 Michal Hocko
2019-10-21 20:32 ` [MODERATED] [PATCH v7 10/10] TAAv7 10 Pawan Gupta
2019-10-21 21:32 ` [MODERATED] Re: [PATCH v7 00/10] TAAv7 0 Andy Lutomirski
2019-10-21 23:06   ` Andrew Cooper
2019-10-22  0:34   ` Pawan Gupta
2019-10-22  4:10 ` [MODERATED] Jon Masters
2019-10-22  5:53   ` [MODERATED] Pawan Gupta
2019-10-22  7:58 ` [MODERATED] Re: ***UNCHECKED*** [PATCH v7 07/10] TAAv7 7 Michal Hocko
2019-10-22 16:55   ` [MODERATED] " Pawan Gupta
2019-10-22  8:00 ` [MODERATED] Re: ***UNCHECKED*** [PATCH v7 09/10] TAAv7 9 Michal Hocko
2019-10-22  8:15 ` [MODERATED] Re: ***UNCHECKED*** [PATCH v7 03/10] TAAv7 3 Michal Hocko
2019-10-22 14:42   ` Josh Poimboeuf
2019-10-22 16:48     ` [MODERATED] " Pawan Gupta
2019-10-22 17:01       ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-10-22 17:35         ` Josh Poimboeuf
2019-10-22 14:38 ` [MODERATED] " Borislav Petkov
2019-10-22 16:58   ` Pawan Gupta
2019-10-22 14:48 ` Borislav Petkov
2019-10-22 17:00   ` Pawan Gupta
2019-10-22 17:16     ` [MODERATED] " Borislav Petkov
2019-10-22 18:07       ` [MODERATED] " Pawan Gupta
2019-10-22 15:07 ` Borislav Petkov
2019-10-22 18:36   ` Pawan Gupta
2019-10-22 18:59     ` [MODERATED] " Borislav Petkov
2019-10-22 16:51 ` [MODERATED] Re: [PATCH v7 04/10] TAAv7 4 Borislav Petkov
2019-10-22 17:02   ` Borislav Petkov
2019-10-22 18:00     ` Pawan Gupta
2019-10-22 18:12       ` [MODERATED] " Borislav Petkov
2019-10-22 19:16         ` Luck, Tony
2019-10-22 19:28           ` [MODERATED] " Borislav Petkov
2019-10-22 20:02             ` Luck, Tony
2019-10-22 20:48               ` [MODERATED] Jon Masters
2019-10-22 20:54               ` [MODERATED] Re: [PATCH v7 04/10] TAAv7 4 Borislav Petkov
2019-10-22 21:38                 ` Josh Poimboeuf
2019-10-22 21:46                   ` Borislav Petkov
2019-10-22 22:06                     ` Josh Poimboeuf
2019-10-22 22:13                       ` Borislav Petkov
2019-10-22 17:44   ` Pawan Gupta
2019-10-22 19:04     ` [MODERATED] " Borislav Petkov
2019-10-22 21:29       ` [MODERATED] " Pawan Gupta
2019-10-22 21:53         ` Borislav Petkov
2019-10-22 22:05           ` Borislav Petkov [this message]
2019-10-23  0:27             ` Pawan Gupta
2019-10-23  5:25               ` Pawan Gupta
2019-10-23  6:46                 ` Borislav Petkov
2019-10-23 13:28                   ` Pawan Gupta
2019-10-23 14:39                     ` Borislav Petkov
2019-10-23  1:33   ` Pawan Gupta
2019-10-23  6:48     ` Borislav Petkov
2019-10-22 17:25 ` [MODERATED] Re: [PATCH v7 01/10] TAAv7 1 Josh Poimboeuf
2019-10-23  9:26   ` Borislav Petkov
2019-10-22 17:26 ` Josh Poimboeuf
2019-10-22 20:44   ` [MODERATED] Jon Masters
2019-10-22 17:47 ` [MODERATED] Re: [PATCH v7 03/10] TAAv7 3 Josh Poimboeuf
2019-10-22 18:39 ` [MODERATED] Re: [PATCH v7 10/10] TAAv7 10 Josh Poimboeuf
2019-10-23  7:24   ` Borislav Petkov
2019-10-22 21:20 ` [MODERATED] Re: [PATCH v7 04/10] TAAv7 4 Josh Poimboeuf
2019-10-22 21:35   ` Andrew Cooper
2019-10-22 21:44     ` Josh Poimboeuf
2019-10-22 22:03       ` Andrew Cooper
2019-10-23  1:16         ` Josh Poimboeuf
2019-10-23 15:46 ` [MODERATED] Re: [PATCH v7 00/10] TAAv7 0 Borislav Petkov
2019-10-23 17:11   ` Josh Poimboeuf
2019-10-23 21:49     ` Borislav Petkov
2019-10-23 22:12   ` Pawan Gupta
2019-10-24 14:08     ` Borislav Petkov
     [not found] ` <5dae165e.1c69fb81.4beee.e271SMTPIN_ADDED_BROKEN@mx.google.com>
2019-10-24 20:53   ` [MODERATED] Re: [PATCH v7 06/10] TAAv7 6 Paolo Bonzini
2019-10-24 21:00     ` Luck, Tony
2019-10-24 21:33       ` Paolo Bonzini

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