Re: [kvm-devel] [PATCH] (big) real mode emulation - or instruction correction

[Avi K. <av...@qu...>]

Nitin A Kamble wrote:
> Hi Avi,
>   This patch corrects the emulation of the instruction "or" for opcodes
> 0xc & 0cd.
>   Please Apply.
>   

> +	case 0x0c: 		/* or al imm8 */
> +		dst.type = OP_REG;
> +		dst.ptr = &_regs[VCPU_REGS_RAX];
> +		dst.val = *(u8 *)dst.ptr;
> +		dst.bytes = 1;
> +		dst.orig_val = dst.val;
> +		goto or;
> +	case 0x0d:		/* or ax imm16, or eax imm32 */
> +		dst.type = OP_REG;
> +		dst.bytes = op_bytes;
> +		dst.ptr = &_regs[VCPU_REGS_RAX];
> +		if (op_bytes == 2)
> +			dst.val = *(u16 *)dst.ptr;
> +		else
> +			dst.val = *(u32 *)dst.ptr;
> +		dst.orig_val = dst.val;
> +		goto or;

Instead of repeating this code for all instructions that use the
accumulator implicitly, we should define a bit in the decoder flags
(like DstAcc) so that all the code is consolidated in the decoder.  This
applies to 'sub imm' and 'cmp correction', and probably others as well.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.