On 09/08/2018 17:03, Paolo Bonzini wrote: > On 09/08/2018 16:55, Olaf Hering wrote: >> >>> I think the simplest fix is for the map >>> cache to set aside a zero page and return it whenever it is asked for a >>> ballooned page. >> Can qemu actually know if it ran into a ballooned page? I think no. > > Well, xen_map_cache knows that it has run into *something like* a > ballooned page when it returns NULL. :)
... however, that works for reading to the page, not writing. The problem is that your patch is incomplete. There are many more callers of qemu_ram_ptr_length, and none of them check the result. Paolo
