From mboxrd@z Thu Jan  1 00:00:00 1970
From: Izik Eidos <izik@qumranet.com>
Subject: Re: [PATCH] kvm-userspace: fix memslot assignment
Date: Thu, 31 Jul 2008 15:03:12 +0300
Message-ID: <4891AA00.7060009@qumranet.com>
References: <200807251738.29171.borntraeger@de.ibm.com> <200807281855.04681.borntraeger@de.ibm.com> <488F18B9.1010700@qumranet.com> <200807311001.07426.borntraeger@de.ibm.com> <4891A0DD.5000503@qumranet.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
	kvm <kvm@vger.kernel.org>, Carsten Otte <cotte@de.ibm.com>,
	Olaf Schnapper <os@de.ibm.com>,
	Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
	Izik Eidus <izike@qumranet.com>
To: Avi Kivity <avi@qumranet.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from il.qumranet.com ([212.179.150.194]:54933 "EHLO il.qumranet.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1753540AbYGaMDR (ORCPT <rfc822;kvm@vger.kernel.org>);
	Thu, 31 Jul 2008 08:03:17 -0400
In-Reply-To: <4891A0DD.5000503@qumranet.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

Avi Kivity wrote:
> Christian Borntraeger wrote:
>> Am Dienstag, 29. Juli 2008 schrieb Avi Kivity:
>>  
>>> They all start with 0 AFAIK (kvm also starts with 0, it just wants 
>>> it to be a special slot).
>>>     
>>
>> Now my brain hurts....
>> Ok, so I read this as: ppc, ia64 and s390 can start with slot 0 and 
>> it is not a special slot.
>> On x86 slot 0 is special, if
>> * KVM_CAP_SET_TSS_ADDR is not available
>> or
>> * The ioctl VM_CAP_SET_TSS_ADDR returns <=0
>>
>>   
>
> I think this is right.  Izik can you confirm?

yea kernels that dont have KVM_CAP_SET_TSS_ADDR should be treated like that.

>
>> +#if defined(__x86_64__) || defined(__i386__)
>> +#if defined(KVM_CAP_SET_TSS_ADDR)
>> +    if (ioctl(kvm->fd, KVM_CHECK_EXTENSION, KVM_CAP_SET_TSS_ADDR) > 0)
>>   
>
> Should be <= here?
>
>> +        i++;
>> +#else
>> +    i++;
>> +#endif
>> +#endif
>>   
>
> Suggest a helper, kvm_supports_set_tss_addr(), to reduce further 
> braindamage.
>