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From: Tom Lendacky <thomas.lendacky@amd.com>
To: Brian Gerst <brgerst@gmail.com>
Cc: the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	David Woodhouse <dwmw@amazon.co.uk>, Paul Turner <pjt@google.com>
Subject: Re: [PATCH v1 1/3] x86/cpu/AMD: Make LFENCE a serializing instruction
Date: Fri, 5 Jan 2018 10:36:40 -0600	[thread overview]
Message-ID: <29225f25-033b-92d5-2e19-29eb557665d6@amd.com> (raw)
In-Reply-To: <CAMzpN2hi9QkamCX2QvS8ukwJQtGKShLs6V2RmM8VjXF+8PdDxQ@mail.gmail.com>

On 1/5/2018 10:35 AM, Brian Gerst wrote:
> On Fri, Jan 5, 2018 at 11:07 AM, Tom Lendacky <thomas.lendacky@amd.com> wrote:
>> To aid in speculation control, make LFENCE a serializing instruction.
>> This is done by setting bit 1 of MSR 0xc0011029 (DE_CFG).  Some families
>> that support LFENCE do not have this MSR.  For these families, the LFENCE
>> instruction is already serializing.
> 
> Does this require a microcode update?

No, it doesn't.

Thanks,
Tom

> 
> --
> Brian Gerst
> 

  reply	other threads:[~2018-01-05 16:36 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-05 16:07 [PATCH v1 0/3] x86/cpu/AMD: Make LFENCE a serializing instruction on AMD Tom Lendacky
2018-01-05 16:07 ` [PATCH v1 1/3] x86/cpu/AMD: Make LFENCE a serializing instruction Tom Lendacky
2018-01-05 16:35   ` Brian Gerst
2018-01-05 16:36     ` Tom Lendacky [this message]
2018-01-06 21:05   ` [tip:x86/pti] " tip-bot for Tom Lendacky
2018-01-05 16:07 ` [PATCH v1 2/3] x86/cpu/AMD: Use LFENCE_RDTSC instead of MFENCE_RDTSC Tom Lendacky
2018-01-06 21:06   ` [tip:x86/pti] " tip-bot for Tom Lendacky
2018-01-08 10:08     ` Thomas Gleixner
2018-01-08 10:23       ` Woodhouse, David
2018-01-08 10:25         ` Thomas Gleixner
2018-01-08 10:40       ` Andrew Cooper
2018-01-08 11:10         ` Thomas Gleixner
2018-01-08 14:47           ` Tom Lendacky
2018-01-08 14:54             ` Andrew Cooper
2018-01-08 16:48               ` Dr. David Alan Gilbert
2018-01-08 17:01                 ` Paolo Bonzini
2018-01-08 17:39                   ` Tom Lendacky
2018-01-08 17:42                     ` Paolo Bonzini
2018-01-17 17:21                   ` Tom Lendacky
2018-01-17 17:53                     ` Paolo Bonzini
2018-01-08 15:02             ` David Woodhouse
2018-01-08 15:15             ` Thomas Gleixner
2018-01-08 17:31               ` Tom Lendacky
2018-01-08 20:57                 ` Thomas Gleixner
2018-01-05 16:08 ` [PATCH v1 3/3] x86/msr: Remove now unused definition of MFENCE_RDTSC feature Tom Lendacky
2018-01-06 21:06   ` [tip:x86/pti] " tip-bot for Tom Lendacky
2018-01-05 16:56 ` [PATCH v1 0/3] x86/cpu/AMD: Make LFENCE a serializing instruction on AMD Borislav Petkov

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