From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@qumranet.com>
Subject: Re: [PATCH] x86 emulator: Add in/out instructions, opcodes (0xe4-0xe7,
   0xec-0xef)
Date: Mon, 11 Aug 2008 14:45:50 +0300
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References: <20080804195719.GA7552@mohd-laptop>
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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 adds instructions 'in' and 'out' to the x86 emulator.
> 

> +	SrcNone | ByteOp | ImplicitOps, SrcNone |ImplicitOps,

Missing blank.



>  	case 0xe8: /* call (near) */ {
>  		long int rel;
>  		switch (c->op_bytes) {
> @@ -1732,6 +1744,26 @@ special_insn:
>  		jmp_rel(c, c->src.val);
>  		c->dst.type = OP_NONE; /* Disable writeback. */
>  		break;
> +	case 0xec: /* in al,dx */
> +	case 0xed: /* in (e/r)ax,dx */
> +		port = c->regs[VCPU_REGS_RDX];
> +	in:	if(kvm_emulate_pio(ctxt->vcpu, NULL, 1,

missing blank.

> +				   (c->d & ByteOp) ? 1 : c->op_bytes,
> +				   port) != 0) { 
> +			c->eip = saved_eip;
> +			return -1;
> +		}
> +		return 0;
> +	case 0xee: /* out al,dx */
> +	case 0xef: /* out (e/r)ax,dx */
> +		port = c->regs[VCPU_REGS_RDX];
> +	out:	if(kvm_emulate_pio(ctxt->vcpu, NULL, 0,
> +				   (c->d & ByteOp) ? 1 : c->op_bytes,
> +				   port) != 0) { 
> +			c->eip = saved_eip;
> +			return -1;


goto cannot_emulate?

> +		}
> +		return 0;

It would be simpler to fold the in and out implementations together (and 
extract the direction flag from the instruction byte).