On 10/24/2014 07:57 PM, Andy Lutomirski wrote: > > KVM_EXIT_UNKNOWN is a kvm bug, we don't really know whether it was > > triggered by a priveledged application. Let's not kill the guest: WARN > > and inject #UD instead. > > This scares me a bit. For guest CPL3, it's probably okay. For guest > CPL0, on the other hand, #UD might not use IST (or a task switch on > 32-bit guests), resulting in possible corruption if unprivileged code > controls SP. Admittedly, there aren't that many contexts from which > that should happen (on Linux, at least), but something like #DF (or even > a triple fault) might be safer if the guest is at CPL0 when this happens. This in practice will only happen for VMX instructions (INVVPID in this patch set, INVEPT on some older kernels); all other intercepts can be turned on or off at will. For unknown exits we will not have exposed those instructions in the VMX capabilities (or perhaps we will not have exposed VMX at all in CPUID on the older kernels). So #UD is the right thing to do. 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
