Re: [PATCH] x86: don't deliver NMI to PVH Dom0

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

On 11/12/14 10:47, Jan Beulich wrote:
> ... for the time being: The mechanism used depends on the domain's use
> of the IRET hypercall.
>
> Also drop two bogus code lines spotted while going through the involved
> code paths: Addresses of per-CPU variables can't possibly be NULL, and
> the setting of st->vcpu in send_guest_trap()'s MCE case is redundant
> with an earlier cmpxchgptr().
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

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

>
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -3168,7 +3168,6 @@ static void nmi_mce_softirq(void)
>      int cpu = smp_processor_id();
>      struct softirq_trap *st = &per_cpu(softirq_trap, cpu);
>  
> -    BUG_ON(st == NULL);
>      BUG_ON(st->vcpu == NULL);
>  
>      /* Set the tmp value unconditionally, so that
> @@ -3233,7 +3232,7 @@ static void nmi_hwdom_report(unsigned in
>  {
>      struct domain *d = hardware_domain;
>  
> -    if ( (d == NULL) || (d->vcpu == NULL) || (d->vcpu[0] == NULL) )
> +    if ( !d || !d->vcpu || !d->vcpu[0] || !is_pv_domain(d) /* PVH fixme */ )
>          return;
>  
>      set_bit(reason_idx, nmi_reason(d));
> @@ -3674,7 +3673,6 @@ int send_guest_trap(struct domain *d, ui
>  
>          if ( !test_and_set_bool(v->mce_pending) ) {
>                  st->domain = d;
> -                st->vcpu = v;
>                  st->processor = v->processor;
>  
>                  /* not safe to wake up a vcpu here */