linux-kernel - Re: [PATCH v3 1/2] x86, mwaitt: add monitorx and mwaitx instruction

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Message-ID: <20150611141428.GA21621@hr-slim.amd.com>
Date:	Thu, 11 Jun 2015 22:14:28 +0800
From:	Huang Rui <ray.huang@....com>
To:	Borislav Petkov <bp@...e.de>
CC:	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	John Stultz <john.stultz@...aro.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	<linux-kernel@...r.kernel.org>, <x86@...nel.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Aaron Lu <aaron.lu@...el.com>,
	Suravee Suthikulanit <suravee.suthikulpanit@....com>,
	Tony Li <tony.li@....com>, Ken Xue <ken.xue@....com>
Subject: Re: [PATCH v3 1/2] x86, mwaitt: add monitorx and mwaitx instruction

On Thu, Jun 11, 2015 at 04:19:04PM +0200, Borislav Petkov wrote:
> On Thu, Jun 11, 2015 at 10:14:10PM +0800, Huang Rui wrote:
> > On AMD Carrizo processors (Family 15h, Model 60h-6fh), there is a new
> > feature called MWAITT (Mwait with a timer) as an extension of
> > Monitor/Mwait.
> > 
> > MWAITT, another name is MWAITX (MWAIT with extensions), has a configurable
> > timer that causes MWAITX to exit on expiration.
> > 
> > Compared with MONITOR/MWAIT, there are minor differences in opcode and
> > input parameters.
> > 
> > MWAITX ECX[1]: enable timer if set
> > MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks
> > 
> >                 MWAIT                           MWAITX
> > opcode          0f 01 c9           |            0f 01 fb
> > ECX[0]                  value of RFLAGS.IF seen by instruction
> > ECX[1]          unused/#GP if set  |            enable timer if set
> > ECX[31:2]                     unused/#GP if set
> > EAX                           unused (reserve for hint)
> > EBX[31:0]       unused             |            max wait time (loops)
> > 
> >                 MONITOR                         MONITORX
> > opcode          0f 01 c8           |            0f 01 fa
> > EAX                     (logical) address to monitor
> > ECX                     #GP if not zero
> > 
> > The software P0 frequency is the same as the TSC frequency.
> > 
> > Max timeout = EBX/(TSC frequency)
> 
> As suggested last time, please put the description of MWAITX over
> __mwaitx() in the code as comments below. See below.
> 

Apology to miss that. Will do it at once.

Thanks,
Rui
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