linux-kernel - RE: [PATCH v2] x86: add a new SMP bring up way for tboot case

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Date:	Thu, 11 Apr 2013 07:16:38 +0000
From:	"Ren, Qiaowei" <qiaowei.ren@...el.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"Maliszewski, Richard L" <richard.l.maliszewski@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tboot-devel@...ts.sourceforge.net" 
	<tboot-devel@...ts.sourceforge.net>,
	Xiaoyan Zhang <xiaoyan.zhang@...el.com>,
	"Wei, Gang" <gang.wei@...el.com>
Subject: RE: [PATCH v2] x86: add a new SMP bring up way for tboot case

> -----Original Message-----
> From: H. Peter Anvin [mailto:hpa@...or.com]
> Sent: Wednesday, March 20, 2013 11:02 AM
> To: Ren, Qiaowei
> Cc: Thomas Gleixner; Ingo Molnar; x86@...nel.org; Maliszewski, Richard L;
> linux-kernel@...r.kernel.org; tboot-devel@...ts.sourceforge.net; Xiaoyan
> Zhang; Wei, Gang
> Subject: Re: [PATCH v2] x86: add a new SMP bring up way for tboot case
> 
> On 03/19/2013 07:14 PM, Ren, Qiaowei wrote:
> > Any comments on this patch?
> >
> > Thanks,
> > Qiaowei
> 
> The biggest question is probably if we can use an existing hook of some sort.
> 
> Overriding the apic method is probably not the right way to go, though.
>  tglx, do you have any opinions here?
> 

If we can't use an existing hook, could you please give me any suggestion about other opinions here?

> Furthermore, this really is not nice:
>
> > +int tboot_wake_up(int apicid, unsigned long sipi_vec) {
> > +	if (!tboot_enabled())
> > +		return 0;
> > +
> > +	if ((tboot->version < 6) ||
> > +	    !(tboot->flags & TB_FLAG_AP_WAKE_SUPPORT))
> > +		return 0;
> > +
> > +	tboot->ap_wake_addr = sipi_vec;
> > +	tboot->ap_wake_trigger = apicid;
> > +
> > +	return 1;
> > +}
> 
> Not only don't you set boot_error for the code above it, but there is absolutely
> no indication how that does its job (are those active operations?  If so they
> should use writel()), nor does it include any kind of synchronization.
> 

Ok. I should add some comments to explain how that does its job. 
But I guess boot_error don't have to be set inside this function.

Thanks,
Qiaowei

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