On Fri, Oct 24, 2014 at 2:54 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: > 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. >
Fair enough. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
