Re: [PATCH] x86/vmx: fix vmx_is_singlestep_supported return value

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 24/08/2015 20:55, Tamas K Lengyel wrote:
> The function supposed to return a boolean but instead it returned
> the value 0x8000000 which is the Intel internal flag for MTF. This has
> caused various checks using this function to falsely report no MTF
> capability.

Ouch.  Given than bool_t is current signed char, that won't be of much use.

>
> Signed-off-by: Tamas K Lengyel <tlengyel@novetta.com>
> ---
>  xen/arch/x86/hvm/vmx/vmx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index 999defe..35bcd79 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -1768,7 +1768,7 @@ static void vmx_enable_msr_exit_interception(struct domain *d)
>  
>  static bool_t vmx_is_singlestep_supported(void)
>  {
> -    return cpu_has_monitor_trap_flag;
> +    return cpu_has_monitor_trap_flag ? 1 : 0;

Prevailing style would tend towards !!cpu_has_monitor_trap_flag

Either way, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>  }
>  
>  static void vmx_vcpu_update_eptp(struct vcpu *v)