Re: [kvm-unit-tests PATCH v2] x86: emulator: Fix h_mem usage in tests_smsw

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/12/2014 16:44, Chris J Arges wrote:
> In emulator.c/tests_smsw, smsw (3) fails because h_mem isn't being set correctly
> before smsw is called. By using the + constraint modifier for memory we can
> ensure the compiler no longer optimizes out the assignment before smsw.
> 
> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
> ---
>  x86/emulator.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/x86/emulator.c b/x86/emulator.c
> index 5aa4dbf..1e05574 100644
> --- a/x86/emulator.c
> +++ b/x86/emulator.c
> @@ -359,7 +359,7 @@ void test_smsw(uint64_t *h_mem)
>  
>  	/* Trigger exit on smsw */
>  	*h_mem = 0x12345678abcdeful;
> -	asm volatile("smsw %0" : "=m"(*h_mem));
> +	asm volatile("smsw %0" : "+m"(*h_mem));
>  	report("smsw (3)", msw == (unsigned short)*h_mem &&
>  		(*h_mem & ~0xfffful) == 0x12345678ab0000ul);
>  }
> 

Applied, thanks.

Paolo