2016-11-22 11:43-0800, Nadav Amit: > I admit my wrongdoings, but I still think the fix should have been to > remove the entire recovery logic and just return X86EMUL_UNHANDLEABLE if > something goes wrong (exception). This will kill the misbehaving process > but keep the VM running. X86EMUL_UNHANDLEABLE will kill the whole VM (on QEMU, other userspaces might handle the instruction and resume KVM). The recovery path is in the spec, which means that nothing goes wrong. I think we implement the spec quite well now, so keeping the #GP and CS recovery is slightly better, although not safer. > Otherwise, a malicious VM process, which can somehow control descriptors > (LDT?) may modify the descriptor during the emulation and get the system > to inconsistent state and prevent the VM-entry. We restore the original CS -- malicious guest would get killed on a failed VM entry anyway, so the difference is only in KVM internal error code (assuming there are no other bugs). Am I misunderstanding something? -- 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
