Re: [PATCH 9/9] KVM: x86: smsw emulation is incorrect in 64-bit mode

[Nadav Amit]

On Jun 5, 2014, at 5:53 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:

> Il 02/06/2014 17:34, Nadav Amit ha scritto:
>> In 64-bit mode, when the destination is a register, the assignment is done
>> according to the operand size. Otherwise (memory operand or no 64-bit mode), a
>> 16-bit assignment is performed.
> 
> I'm sorry, I'm missing the place where 64-bit mode is taken into account?
It is not, since on 32-bit mode the high-order 16 bits of a register destination are undefined. 
If I recall correctly, in this case the high-order 16-bits on native system actually reflect the high-order 16-bits of CR0.

Therefore, regardless to the mode of operation:
1. If the target is memory - the destination is 16-bit
2. If the target is a register - the register is written according to the operand size.

Nadav--
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