Re: [Xen-devel] How does hypervisor handle the hypercalls fromguest OSes?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

A couple of comments...

> long hypervisor_temp(struct task_struct *p, dom0_tmp_t *tmp)
> {
>         int ret;
>         unsigned long cpu_mask = 0;
>         int p_size;
> 
>         if ( sizeof(*p->temp) > PAGE_SIZE ) BUG();
> 
>         p->temp = (void *)get_free_page(GFP_KERNEL);
>         clear_page(p->temp);
>         p->temp = tmp->test;
          ^^^^^^^^^^^^^^^^^^^^
The line above looks like debugging you've forgotten to remove?

>         SHARE_PFN_WITH_DOMAIN(virt_to_page(p->temp), p->domain);
> 
>         cpu_mask = mark_guest_event(p, _EVENT_TEMP);
>         guest_event_notify(cpu_mask);
>         put_task_struct(p);
          ^^^^^^^^^^^^^^^^^^^
You probably don't want to decrement p's reference count here. p was
passed into the function as an argument, which usually means that
you are "borrowing" the caller's reference -- and he probably
expects to get it back!

Everything else looks like it is probably okay. The first comment
above could be the problem though -- it looks like the code is plain
wrong. 

 -- Keir


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