Hi, everyone I am studying KVM code. And I try to intercept a guest's read access to a page using VMX and EPT support. According to Intel Manual, the lowest bit of the EPT page table entry is used to control read access to a page. I modified the rmap_write_protect function to remove the VMX_EPT_READABLE_MASK of a spte. This is accomplish by changing the new_spte parameter of mmu_spte_update function. But in KVM, it seems like it is used to indicate whether a page is present or not. So this would trigger the WARN_ON(!is_rmap_spte(new_spte)) and cause the Host to panic. Why can not rmap_write_protect be applied to set the spte to non-present. Does drop_spte function is the only way to intercept a read access of a in guest page. I use kvm-kmod-3.1 and linux kernel 3.1. Can anyone help if I do anything wrong or there is another more elegant way to do it. Thank U for answering. -- Thanks Rui Wu -- 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
