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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH v7 01/10] TAAv7 1
Date: Tue, 22 Oct 2019 12:25:08 -0500	[thread overview]
Message-ID: <20191022172508.7h7d523puvepfjap@treble> (raw)
In-Reply-To: =?utf-8?q?=3Cfc886d6e7492f33d2747d0f13cf4da97cec9a680=2E15716?= =?utf-8?q?88957=2Egit=2Epawan=2Ekumar=2Egupta=40linux=2Eintel=2Ecom=3E?=

On Mon, Oct 21, 2019 at 01:23:02PM -0700, speck for Pawan Gupta wrote:
> From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Subject: [PATCH v7 01/10] x86/tsx: Add enumeration support for IA32_TSX_CTRL
>  MSR
> 
> Transactional Synchronization Extensions (TSX) may be used on certain
> processors as part of a speculative side channel attack.  A microcode
> update for existing processors that are vulnerable to this attack will
> add a new MSR, IA32_TSX_CTRL to allow the system administrator the
> option to disable TSX as one of the possible mitigations.  [Note that
> future processors that are not vulnerable will also support the
> IA32_TSX_CTRL MSR].  Add defines for the new IA32_TSX_CTRL MSR and its
> bits.
> 
> TSX has two sub-features:
> 
> 1. Restricted Transactional Memory (RTM) is an explicitly-used feature
>    where new instructions begin and end TSX transactions.
> 2. Hardware Lock Elision (HLE) is implicitly used when certain kinds of
>    "old" style locks are used by software.
> 
> Bit 7 of the IA32_ARCH_CAPABILITIES indicates the presence of the
> IA32_TSX_CTRL MSR.
> 
> There are two control bits in IA32_TSX_CTRL MSR:
> 
>   Bit 0: When set it disables the Restricted Transactional Memory (RTM)
>          sub-feature of TSX (will force all transactions to abort on the
> 	 XBEGIN instruction).
> 
>   Bit 1: When set it disables the enumeration of the RTM and HLE feature
>          (i.e. it will make CPUID(EAX=7).EBX{bit4} and
>          CPUID(EAX=7).EBX{bit11} read as 0).
> 
> The other TSX sub-feature, Hardware Lock Elision (HLE), is unconditionally
> disabled

How is HLE unconditionally disabled?  Is it done by the above mentioned
microcode?  Is there a way to enable it?

> but still enumerated as present by CPUID(EAX=7).EBX{bit4}.

... unless disabled via bit 1 of IA32_TSX_CTRL_MSR?

[ Also please add the above clarifications to the patch description. ]

-- 
Josh

  parent reply	other threads:[~2019-10-22 17:25 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
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 ` Josh Poimboeuf [this message]
2019-10-23  9:26   ` [MODERATED] Re: [PATCH v7 01/10] TAAv7 1 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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