On 04/07/16 20:27, Jan Beulich wrote: >>>> On 07.04.16 at 10:39, <rcojoc...@bitdefender.com> wrote: >> Theoretically it is possible for mem_access_emulate_each_rep to be >> true even when current->arch.vm_event == NULL, so add an extra >> check to hvmemul_virtual_to_linear(). > > Mind saying what those theoretical conditions are when this might > happen?
This could happen if someone were to call xc_monitor_emulate_each_rep(), but not xc_monitor_enable() (when current->arch.vm_event gets allocated), or after someone called both, but afterwards called xc_monitor_disable() (when current->arch.vm_event gets freed). >> --- a/xen/arch/x86/hvm/emulate.c >> +++ b/xen/arch/x86/hvm/emulate.c >> @@ -514,7 +514,7 @@ static int hvmemul_virtual_to_linear( >> * vm_event being triggered for repeated writes to a whole page. >> */ >> if ( unlikely(current->domain->arch.mem_access_emulate_each_rep) && >> - current->arch.vm_event->emulate_flags != 0 ) >> + current->arch.vm_event && current->arch.vm_event->emulate_flags != >> 0 ) > > That's then the third instance of "current" here - this needs > latching into a local variable. No problem. Thanks, Razvan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
