>>> On 21.09.15 at 15:31, <rcojoc...@bitdefender.com> wrote:
> --- a/xen/arch/x86/hvm/emulate.c
> +++ b/xen/arch/x86/hvm/emulate.c
> @@ -514,7 +514,8 @@ static int hvmemul_virtual_to_linear(
> * being triggered for repeated writes to a whole page.
> */
> *reps = min_t(unsigned long, *reps,
> - unlikely(current->domain->arch.mem_access_emulate_enabled)
> + unlikely(current->domain->arch.mem_access_emulate_enabled
> &&
> + current->domain->arch.mem_access_emulate_each_rep)
> ? 1 : 4096);
unlikely() should not wrap compound conditions, or else its effect of
eliminating mis-predicted branches from the fast path won't be
achieved. In the case here I wonder though whether you couldn't
simply test only ->arch.mem_access_emulate_each_rep.
> --- a/xen/arch/x86/monitor.c
> +++ b/xen/arch/x86/monitor.c
> @@ -79,6 +79,12 @@ int monitor_domctl(struct domain *d, struct
> xen_domctl_monitor_op *mop)
> return 0;
> }
>
> + if ( mop->op == XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP )
> + {
> + d->arch.mem_access_emulate_each_rep = !!mop->event;
> + return 0;
> + }
Considering that there's another "if(mop->op == ...)" right above
this, these two together should become another switch().
Jan
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