From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH] test: Add emulator test for iret instruction
Date: Wed, 28 Jul 2010 16:55:33 -0300
Message-ID: <20100728195533.GA29917@amt.cnet>
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To: Mohammed Gamal <m.gamal005@gmail.com>
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On Wed, Jul 28, 2010 at 12:39:01PM +0300, Mohammed Gamal wrote:
> This adds a unit test for real mode emulation of the iret instruction
> 
> Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
> 
> ---
> Changes from v1:
> - Added test for 16-bit iret
> - Added tests for returned eflags
> ---
>  kvm/test/x86/realmode.c |   79 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 79 insertions(+), 0 deletions(-)
> 
> diff --git a/kvm/test/x86/realmode.c b/kvm/test/x86/realmode.c
> index bd79348..74456c3 100644
> --- a/kvm/test/x86/realmode.c
> +++ b/kvm/test/x86/realmode.c
> @@ -865,6 +865,84 @@ void test_pusha_popa()
>  		print_serial("Pusha/Popa Test2: PASS\n");
>  }
>  
> +void test_iret()
> +{
> +	struct regs inregs = { 0 }, outregs;
> +
> +	MK_INSN(iret32, "pushf\n\t"
> +			"pushl %cs\n\t"
> +			"call 1f\n\t" /* a near call will push eip onto the stack */
> +			"jmp 2f\n\t"
> +			"1: iret\n\t"
> +			"2:\n\t"
> +		     );
> +
> +	MK_INSN(iret16, "pushfw\n\t"
> +			"pushw %cs\n\t"
> +			"callw 1f\n\t"
> +			"jmp 2f\n\t"
> +			"1: iretw\n\t"
> +			"2:\n\t");

Unless iret causes a task switch, it will not cause an exit.