From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH 2 of 2 V4] x86/HVM: fixed _hvm_hw_fix_cpu()
Date: Thu, 24 Jan 2013 13:00:41 +0000
Message-ID: <CD26E0F9.4A40D%keir.xen@gmail.com>
References: <20130124121201.GD18850@ocelot.phlegethon.org>
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To: Tim Deegan <tim@xen.org>, Razvan Cojocaru <rzvncj@gmail.com>
Cc: xen-devel@lists.xensource.com, JBeulich@suse.com
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On 24/01/2013 12:12, "Tim Deegan" <tim@xen.org> wrote:

> At 17:46 +0200 on 23 Jan (1358963209), Razvan Cojocaru wrote:
>> Prevent the compiler from re-ordering the reads and writes.
>> Suggested by Jan Beulich.
>> 
>> Signed-off-by: Razvan Cojocaru <rzvncj@gmail.com>
> 
> Acked-by: Tim Deegan <tim@xen.org>

Acked-by: Keir Fraser <keir@xen.org>

>> diff -r 3a9979cf50f3 -r 550e437674c7 xen/include/public/arch-x86/hvm/save.h
>> --- a/xen/include/public/arch-x86/hvm/save.h Wed Jan 23 17:27:20 2013 +0200
>> +++ b/xen/include/public/arch-x86/hvm/save.h Wed Jan 23 17:44:20 2013 +0200
>> @@ -269,15 +269,20 @@ struct hvm_hw_cpu_compat {
>>  };
>>  
>>  static inline int _hvm_hw_fix_cpu(void *h) {
>> -    struct hvm_hw_cpu *new=h;
>> -    struct hvm_hw_cpu_compat *old=h;
>> +
>> +    union hvm_hw_cpu_union {
>> +        struct hvm_hw_cpu nat;
>> +        struct hvm_hw_cpu_compat cmp;
>> +    };
>> +
>> +    union hvm_hw_cpu_union *ucpu = (union hvm_hw_cpu_union *)h;;
>>  
>>      /* If we copy from the end backwards, we should
>>       * be able to do the modification in-place */
>> -    new->error_code=old->error_code;
>> -    new->pending_event=old->pending_event;
>> -    new->tsc=old->tsc;
>> -    new->msr_tsc_aux=0;
>> +    ucpu->nat.error_code = ucpu->cmp.error_code;
>> +    ucpu->nat.pending_event = ucpu->cmp.pending_event;
>> +    ucpu->nat.tsc = ucpu->cmp.tsc;
>> +    ucpu->nat.msr_tsc_aux = 0;
>>  
>>      return 0;
>>  }
>> 
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> 
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