Gleb Natapov wrote: > On Tue, Feb 16, 2010 at 11:14:45AM +0100, Jan Kiszka wrote: >> Gleb Natapov wrote: >>> On Tue, Feb 16, 2010 at 11:04:10AM +0100, Jan Kiszka wrote: >>>> Gleb Natapov wrote: >>>>> On Tue, Feb 16, 2010 at 10:16:12AM +0100, Jan Kiszka wrote: >>>>>> Found while browsing Xen code: While we assume that the STI interrupt >>>>>> shadow also inplies virtual NMI blocking, some processors may have a >>>>>> different opinion (SDM 3: 22.3). To avoid misunderstandings that would >>>>>> cause endless VM entry attempts, translate STI into MOV SS blocking when >>>>>> requesting the NMI window. >>>>>> >>>>> Why not just remove "block by STI" check in vmx_nmi_allowed()? IIRC this >>>>> is documented that on some CPUs STI does not block NMI. >>>>> >>>> Probably because we will stumble and fall on those CPUs that do care. >>>> >>> But this defines behaviour of cpu _we_ emulate. So on _our_ cpu NMI will >>> not be blocked by STI. >> The host CPU decides if it accepts an NMI injections while > Are you sure? I haven't found such check during VMENTRY. I also only find the explicitly stated exclusion of MOV SS blocking vs. NMI injection. If we can rely on this, removing STI blocking from vmx_nmi_allowed should suffice. Or, better, can we get an official confirmation from Intel? Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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
