Re: [kvm-devel] [PATCH] Handle vma regions with no backing page (v2)

[Anthony L. <ali...@us...>]

Avi Kivity wrote:
> It depends on what's going on?  Does a page table point to mmio?  Or 
> the glommerclock?
>
> Not sure there is a single answer.
>
>> Perhaps we should be replacing consumers of gfn_to_page() with 
>> copy_to_user() instead?
>
> Indeed we should.  The problem is access in atomic contexts.  It's 
> easy to detect failure, but not always easy to handle it.

So I think we should replace it with a rate limited printk and returning 
bad_page.  That way the guest can't exploit it and we'll still hopefully 
get printk()s to track down instances of things going bad.

Regards,

Anthony Liguori