From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@qumranet.com>
Subject: Re: [PATCH] x86_emulate: Emulate nop and xchg reg,rax (0x90 - 0x97)
 instructions
Date: Sat, 14 Jun 2008 19:58:10 +0300
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References: <52d4a3890806140926q49fa0976p77ee70a04b6a749b@mail.gmail.com>
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Cc: kvm@vger.kernel.org, riel@surriel.com
To: Mohammed Gamal <m.gamal005@gmail.com>
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Mohammed Gamal wrote:
> This patch fixes the previous nop patch and adds the xchg reg,rax
> instruction opcodes.
>
>   
> +	case 0x90: /* nop / xchg r8,rax */
> +		if(! (c->rex_prefix & 1) )
> +			break;

space after if.

> +		c->dst.ptr = decode_register( (c->b & 7) | ((c->rex_prefix & 1) <<
> 3), c->regs, 0);
> +		c->dst.val = *(c->dst.ptr);
> +		goto xchg;		
>   

You can have the destination autodecoded by using DstReg instead of 
ImplicitOps.  Otherwise, looks fine.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.