Re: [PATCH kvm-unit-tests 2/4] x86: vmx: fix vm{launch,resume} early exit logic

[Paolo Bonzini <pbonzini@redhat.com>]

On 18/03/2016 23:39, Peter Feiner wrote:
> If vmlaunch or vmresume returns immediately, there's definitely been
> an error -- rflags only needs to be consulted to determine what
> error occurred. By setting fail=1 unconditionally, the test framework
> will now detect problems with rflags *not* being set properly.

You should still do the setbe, and follow it with orl $2, %0.  Then if
fail==2 there is a problem.

Paolo

> Signed-off-by: Peter Feiner <pfeiner@google.com>
> ---
>  x86/vmx.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/x86/vmx.c b/x86/vmx.c
> index b2e015f..27e85eb 100644
> --- a/x86/vmx.c
> +++ b/x86/vmx.c
> @@ -911,6 +911,7 @@ static int vmx_run()
>  	u32 ret = 0, fail = 0;
>  
>  	while (1) {
> +
>  		asm volatile (
>  			"mov %%rsp, %%rsi\n\t"
>  			"mov %2, %%rdi\n\t"
> @@ -926,7 +927,7 @@ static int vmx_run()
>  			"vmresume\n\t"
>  			"2: "
>  			SAVE_GPR_C
> -			"setbe %0\n\t"
> +			"movl $1, %0\n\t"
>  			"jmp 3f\n\t"
>  			"vmx_return:\n\t"
>  			SAVE_GPR_C
>