On 08/02/2017 17:26, Matwey V. Kornilov wrote: > 2017-02-08 11:50 GMT+03:00 Paolo Bonzini <pbonzini@xxxxxxxxxx>: >> On 07/02/2017 21:43, Matwey V. Kornilov wrote: >>> I am not sure that user-space behavior should change. Also I am not >>> sure that qemu should show unsupported CPU flags to guests. >> >> Userspace behavior changed only because you used "-cpu host". "-cpu >> host" tells QEMU to enable everything the kernel can enable, so it can >> break when you update the host kernel. >> >> Without "-cpu host" (e.g. "-cpu Nehalem"), either there would have been >> no change in behavior, or you'd have had a warning before >> >> warning: host doesn't support requested feature: >> CPUID.1H:ECX.tsc_deadline_timer [bit 24] > > -cpu host,-tsc-deadline also works. > >> and no warning afterwards. Is this with KVM nested under VMware, as in >> your launchpad bug report? > > Yes. It is nested under VMware. So the root cause here is that Linux doesn't like VMware's TSC. Paolo
