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

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Date:	Thu, 4 Feb 2016 14:08:41 -0500
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Doug Goldstein <cardoe@...doe.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 02/04/2016 07:58 AM, Doug Goldstein wrote:
> 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.

Yes, I'll do that (or at least have a comment explaining the bits).

Looks like this we should wait with this series though until we figure 
out APIC emulation status.

-boris