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From: Tyler Hicks <tyhicks@canonical.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: ***UNCHECKED*** Re: [PATCH v5 08/11] TAAv5 8
Date: Tue, 15 Oct 2019 14:34:16 -0500	[thread overview]
Message-ID: <20191015193414.GA31070@elm> (raw)
In-Reply-To: <nycvar.YFH.7.76.1910151728110.13160@cbobk.fhfr.pm>

On 2019-10-15 17:32:08, speck for Jiri Kosina wrote:
> On Tue, 15 Oct 2019, speck for Josh Poimboeuf wrote:
> 
> > > > Since all (or most?) modern Intel CPUs are vulnerable to TAA, 
> > > > defaulting to tsx=auto would effectively be the same as defaulting 
> > > > to tsx=off, right?  How does this help with regressions?
> > > 
> > > The mitigation is only needed on CPUs where verw doesn't have the buffer 
> > > clearing semantics.
> > 
> > Can you elaborate?  I have no idea what you're trying to say and how it
> > relates to my question :-)
> 
> Only those CPUs with TSX *and* with MDS_NO need TSX disabled in order to 
> protect from this issues.
> 
> The CPUs that don't enumarate MDS_NO (and therefore got ucode update with 
> verw buffer-clearing semantics) are fully mitigated against TAA by MDS 
> mitigations already.

I don't think "fully mitigated" is true in this case. My understanding
is that they're still vulnerable to cross-thread attacks when SMT is on.

Tyler

> 
> Therefore the set of CPUs where we *really* need to turn of TSX in order 
> to protect from TAA is currently rather minimal (CascadeLake-B, 
> WhiskeyLake-V, CommitLake, CoffeeLake-R), so force-disabling on all CPUs 
> covers way bigger set of platforms than actually needed.
> 
> -- 
> Jiri Kosina
> SUSE Labs

  reply	other threads:[~2019-10-15 19:34 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-05  6:17 [MODERATED] [PATCH v5 00/11] TAAv5 0 Pawan Gupta
2019-10-05  6:26 ` [MODERATED] [PATCH v5 01/11] TAAv5 1 Pawan Gupta
2019-10-05  6:27 ` [MODERATED] [PATCH v5 02/11] TAAv5 2 Pawan Gupta
2019-10-05  6:28 ` [MODERATED] [PATCH v5 03/11] TAAv5 3 Pawan Gupta
2019-10-05  6:29 ` [MODERATED] [PATCH v5 04/11] TAAv5 4 Pawan Gupta
2019-10-05  6:30 ` [MODERATED] [PATCH v5 05/11] TAAv5 5 Pawan Gupta
2019-10-05  6:31 ` [MODERATED] [PATCH v5 06/11] TAAv5 6 Pawan Gupta
2019-10-05  6:32 ` [MODERATED] [PATCH v5 07/11] TAAv5 7 Pawan Gupta
2019-10-05  6:33 ` [MODERATED] [PATCH v5 08/11] TAAv5 8 Pawan Gupta
2019-10-05  6:34 ` [MODERATED] [PATCH v5 09/11] TAAv5 9 Pawan Gupta
2019-10-05  6:35 ` [MODERATED] [PATCH v5 10/11] TAAv5 10 Pawan Gupta
2019-10-05  6:36 ` [MODERATED] [PATCH v5 11/11] TAAv5 11 Pawan Gupta
2019-10-05 10:54 ` [MODERATED] Re: [PATCH v5 02/11] TAAv5 2 Borislav Petkov
2019-10-07 17:48   ` Pawan Gupta
     [not found] ` <5d98396a.1c69fb81.6c7a8.23b1SMTPIN_ADDED_BROKEN@mx.google.com>
2019-10-05 21:43   ` [MODERATED] Re: [PATCH v5 03/11] TAAv5 3 Andy Lutomirski
2019-10-07 17:50     ` Pawan Gupta
     [not found] ` <5d9839a4.1c69fb81.238e9.8312SMTPIN_ADDED_BROKEN@mx.google.com>
2019-10-05 21:45   ` [MODERATED] Re: [PATCH v5 04/11] TAAv5 4 Andy Lutomirski
     [not found] ` <5d983ad2.1c69fb81.63edd.6575SMTPIN_ADDED_BROKEN@mx.google.com>
2019-10-05 21:49   ` [MODERATED] Re: [PATCH v5 09/11] TAAv5 9 Andy Lutomirski
2019-10-07 18:35     ` Pawan Gupta
     [not found] ` <5d9838f1.1c69fb81.f1bab.d886SMTPIN_ADDED_BROKEN@mx.google.com>
2019-10-05 21:49   ` [MODERATED] Re: [PATCH v5 01/11] TAAv5 1 Andy Lutomirski
2019-10-06 17:40     ` Andrew Cooper
     [not found] ` <5d983ad2.1c69fb81.e6640.8f51SMTPIN_ADDED_BROKEN@mx.google.com>
2019-10-06 17:06   ` [MODERATED] Re: [PATCH v5 09/11] TAAv5 9 Greg KH
2019-10-08  6:01     ` Pawan Gupta
2019-10-10 21:31       ` Pawan Gupta
2019-10-11  8:45         ` Greg KH
2019-10-21  8:00           ` Thomas Gleixner
2019-10-08  2:46 ` [MODERATED] Re: [PATCH v5 05/11] TAAv5 5 Josh Poimboeuf
2019-10-09  1:45   ` Pawan Gupta
2019-10-08  2:57 ` [MODERATED] Re: [PATCH v5 09/11] TAAv5 9 Josh Poimboeuf
2019-10-08  6:10   ` Pawan Gupta
2019-10-08 10:49     ` Jiri Kosina
2019-10-09 13:12 ` [MODERATED] Re: ***UNCHECKED*** [PATCH v5 08/11] TAAv5 8 Michal Hocko
2019-10-14 19:41   ` Thomas Gleixner
2019-10-14 19:51     ` [MODERATED] " Jiri Kosina
2019-10-14 21:04       ` [MODERATED] " Borislav Petkov
2019-10-14 21:31         ` Jiri Kosina
2019-10-15  8:01           ` Thomas Gleixner
2019-10-15 10:34             ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-10-15 13:06               ` Josh Poimboeuf
2019-10-15 13:10                 ` Jiri Kosina
2019-10-15 15:26                   ` Josh Poimboeuf
2019-10-15 15:32                     ` Jiri Kosina
2019-10-15 19:34                       ` Tyler Hicks [this message]
2019-10-15 20:00                       ` Josh Poimboeuf
2019-10-15 20:15                         ` Jiri Kosina
2019-10-15 20:35                           ` Jiri Kosina
2019-10-15 20:54                             ` Josh Poimboeuf
2019-10-15 20:56                             ` [MODERATED] " Pawan Gupta
2019-10-15 21:14                               ` Jiri Kosina
2019-10-15 23:12                                 ` Josh Poimboeuf
2019-10-15 23:13                                   ` [MODERATED] [AUTOREPLY] [MODERATED] [AUTOREPLY] Automatic reply: " James, Hengameh M
2019-10-16  4:52                                   ` [MODERATED] " Jiri Kosina
2019-10-16  5:05                                     ` Jiri Kosina
2019-10-21 21:15                                       ` Luck, Tony
2019-10-16  7:14                                     ` Josh Poimboeuf
2019-10-16  7:20                                       ` Jiri Kosina
2019-10-18  1:17                                   ` Ben Hutchings
2019-10-18  4:04                                     ` Pawan Gupta
2019-10-15 17:47               ` Borislav Petkov
2019-10-16  7:26               ` [MODERATED] Re: ***UNCHECKED*** " Jiri Kosina
2019-10-16  7:54                 ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-10-16  9:23                   ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-10-16 12:15                     ` Thomas Gleixner
2019-10-16 18:34                       ` [MODERATED] " Pawan Gupta
2019-10-18  0:14                       ` Pawan Gupta
2019-10-21  8:09                         ` Thomas Gleixner
2019-10-21 12:54                         ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko
2019-10-21 20:01                           ` [MODERATED] " Pawan Gupta
2019-10-21 20:33                             ` Josh Poimboeuf
2019-10-21 20:34                               ` Josh Poimboeuf
2019-10-21 20:33                                 ` Pawan Gupta
2019-10-21 23:01                                   ` Andrew Cooper
2019-10-21 23:37                                     ` Luck, Tony
2019-10-21 23:39                                       ` Andrew Cooper
2019-10-14 21:05       ` [MODERATED] Re: ***UNCHECKED*** " Michal Hocko

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