On Wed, 2017-10-18 at 11:35 +0200, Paolo Bonzini wrote: > On 16/10/2017 02:08, Yi Zhang wrote: > > > And the introspection facility by Mihai uses a completely > > > different API for the introspector, based on sockets rather than ioctls. > > > So I'm not sure this is the right API at all. > > > > Currently, We only block the write access, As far as I know an example, > > we now using it in a security daemon: > > Understood. However, I think QEMU is the wrong place to set this up. > > If the kernel wants to protect _itself_, it should use a hypercall. If > an introspector appliance wants to protect the guest kernel, it should > use the socket that connects it to the hypervisor. We have been looking at using SPP for VMI for quite some time. If a guest kernel will be able to control it (can it do so with EPT?) then it would be useful a simple switch that disables this ability, as an introspector wouldn't want the guest is trying to protect to interfere with it. Also, if Intel doesn't have a specific use case for it that requires separate access to SPP control, then maybe we can fold it into the VMI API we are working on? Thanks, > > Consider It has a server which launching in the host user-space, and a > > client launching in the guest kernel. Yes, they are communicate with > > sockets. The guest kernel wanna protect a special area to prevent all > > the process including the kernel itself modify this area. the client > > could send the guest physical address via the security socket to server > > side, and server would update these protection into KVM. Thus, all the > > write access in a guest specific area will be blocked. > > > > Now the implementation only on the second half(maybe third ^_^) of this > > example: 'How kvm set the write-protect into a specific GFN?' > > > > Maybe a user space tools which use ioctl let kvm mmu update the > > write-protection is a better choice. -- Mihai Donțu
