On 20/03/2018 21:43, hpa@xxxxxxxxx wrote: > What is the security issue? Port 0x80 used for other purposes on > real hardware? In that case, the host kernel would need to know > about it, and could disable this hack, no? Yes, there are DMI-based quirks. > (Such a machine would have a hard time running Linux, too. That > being said, I don't think it would be a bad idea to induce something > like X86_FEATURE_NOIODELAY which would patch out those writes; KVM > guests could set it.) We already do that in KVM guests through pvops. This flag could still be useful if the DMI-based quirks were to set it, but honestly I think that Tim has either a bad driver or some kind of misconfiguration. Paolo
