linux-kernel - Re: [PATCH kvm-unit-tests] x86: test mov DR with ignored mod bits

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Date:	Tue, 27 May 2014 11:24:18 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Nadav Amit <namit@...technion.ac.il>
CC:	gleb@...nel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH kvm-unit-tests] x86: test mov DR with ignored mod bits

Il 26/05/2014 23:06, Nadav Amit ha scritto:
> Tests whether the emulator ignores the mod bits on mov DR instruction.  The
> test performs regular mov to DR0 and reads back the data using custom mov from
> DR0 while mod bits are set to zero. The expected result is obviously the value
> which was written to DR0 before.
>
> The test is performed in realmode and is only expected to fail if the CPU does
> not support unrestricted mode. Note that mov-CR/DR in protected mode are
> usually not handled by the emulator, as their data is available in the exit
> information fields.
>
> Signed-off-by: Nadav Amit <namit@...technion.ac.il>
> ---
>  x86/realmode.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/x86/realmode.c b/x86/realmode.c
> index 9c22d41..839ac34 100644
> --- a/x86/realmode.c
> +++ b/x86/realmode.c
> @@ -1636,6 +1636,16 @@ static void test_perf_memory_rmw(void)
>  	print_serial(" cycles/emulated memory RMW instruction\n");
>  }
>
> +void test_dr_mod(void)
> +{
> +	MK_INSN(drmod, "movl %ebx, %dr0\n\t"
> +		       ".byte 0x0f \n\t .byte 0x21 \n\t .byte 0x0\n\t");
> +	inregs.eax = 0xdead;
> +	inregs.ebx = 0xaced;
> +	exec_in_big_real_mode(&insn_drmod);
> +	report("mov dr with mod bits", R_AX | R_BX, outregs.eax == 0xaced);
> +}
> +
>  void realmode_start(void)
>  {
>  	test_null();
> @@ -1681,6 +1691,7 @@ void realmode_start(void)
>  	test_xlat();
>  	test_salc();
>  	test_fninit();
> +	test_dr_mod();
>  	test_nopl();
>  	test_perf_loop();
>  	test_perf_mov();
>

Thanks, applied.

Paolo
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