On 04/07/2016 09:37, Xiao Guangrong wrote: >>> >> >> It actually is a portion of the physical mmio which is set by vfio mmap. > > So i do not think we need to care its refcount, i,e, we can consider it > as reserved_pfn, > Paolo? nVidia provided me (offlist) with a simple patch that modified VFIO to exhibit the problem, and it didn't use reserved PFNs. This is why the commit message for the patch is not entirely accurate. But apart from this, it's much more obvious to consider the refcount. The x86 MMU code doesn't care if the page is reserved or not; mmu_set_spte does a kvm_release_pfn_clean, hence it makes sense for hva_to_pfn_remapped to try doing a get_page (via kvm_get_pfn) after invoking the fault handler, just like the get_user_pages family of function does. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
