linux-kernel - Re: [Xen-devel] [PATCH v2 07/11] xen/hvmlite: Initialize context for secondary VCPUs

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Message-ID: <56B34B01.50000@cardoe.com>
Date:	Thu, 4 Feb 2016 06:58:41 -0600
From:	Doug Goldstein <cardoe@...doe.com>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	David Vrabel <david.vrabel@...rix.com>, konrad.wilk@...cle.com
Cc:	xen-devel@...ts.xenproject.org, mcgrof@...e.com,
	linux-kernel@...r.kernel.org, roger.pau@...rix.com
Subject: Re: [Xen-devel] [PATCH v2 07/11] xen/hvmlite: Initialize context for
 secondary VCPUs

On 2/2/16 10:58 AM, Boris Ostrovsky wrote:
> On 02/02/2016 11:21 AM, David Vrabel wrote:
>> This needs some more description in the commit message.
>>
>>> --- a/arch/x86/xen/smp.c
>>> +++ b/arch/x86/xen/smp.c
>> [...]
>>> +        hctxt->cpu_regs.x86_32.cs_base = 0;
>>> +        hctxt->cpu_regs.x86_32.cs_limit = ~0u;
>>> +        hctxt->cpu_regs.x86_32.cs_ar = 0xc9b;
>>> +        hctxt->cpu_regs.x86_32.ds_base = 0;
>>> +        hctxt->cpu_regs.x86_32.ds_limit = ~0u;
>>> +        hctxt->cpu_regs.x86_32.ds_ar = 0xc93;
>>> +        hctxt->cpu_regs.x86_32.es_base = 0;
>>> +        hctxt->cpu_regs.x86_32.es_limit = ~0u;
>>> +        hctxt->cpu_regs.x86_32.es_ar = 0xc93;
>>> +        hctxt->cpu_regs.x86_32.ss_base = 0;
>>> +        hctxt->cpu_regs.x86_32.ss_limit = ~0u;
>>> +        hctxt->cpu_regs.x86_32.ss_ar = 0xc93;
>>> +        hctxt->cpu_regs.x86_32.tr_base = 0;
>>> +        hctxt->cpu_regs.x86_32.tr_limit = 0xff;
>>> +        hctxt->cpu_regs.x86_32.tr_ar = 0x8b;
>> Lots of hard-coded values here.  Should this be #defined somewhere?
> 
> We also don't need to set bases to zero since hctxt is kzalloc'd. I'll
> remove that and add a comment.
> 
> As for macros --- I couldn't find the bits defined symbolically anywhere
> and since this is the only place this is used the macros would be local
> here.
> 
> -boris
> 

It could be useful to have them defined locally if only to give them
some more meaning by having a name rather than 0x8b. Just a thought.

-- 
Doug Goldstein


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