Re: [Xen-devel] [PATCH for-4.12 V3] x86/altp2m: fix HVMOP_altp2m_set_domain_state race

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.02.19 at 10:13, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -2150,13 +2150,13 @@ static bool_t vmx_is_singlestep_supported(void)
>      return !!cpu_has_monitor_trap_flag;
>  }
>  
> -static void vmx_vcpu_update_eptp(struct vcpu *v)
> +static void vmx_vcpu_update_eptp(struct vcpu *v, bool altp2m_enabled)
>  {
>      struct domain *d = v->domain;
>      struct p2m_domain *p2m = NULL;
>      struct ept_data *ept;
>  
> -    if ( altp2m_active(d) )
> +    if ( altp2m_enabled )
>          p2m = p2m_get_altp2m(v);
>      if ( !p2m )
>          p2m = p2m_get_hostp2m(d);

With the change you now make to p2m_get_altp2m(), this looks to be
a benign change. Which to me would suggest to either leave the code
alone, or to drop the if() (but - again - not its body) altogether. At
which point the code could be further streamlined, as then the NULL
initializer can go away and the assignment (or then perhaps initializer)
could become "p2m = p2m_get_altp2m(v) ?: p2m_get_hostp2m(d)".
(Generally I'd recommend to leave out the change here, and do the
transformation in a follow-on patch.)

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel