On 24/05/19 09:56, Tao Xu wrote: > +7.19 KVM_CAP_ENABLE_USR_WAIT_PAUSE > + > +Architectures: x86 > +Parameters: args[0] whether feature should be enabled or not > + > +With this capability enabled, a VM can use UMONITOR, UMWAIT and TPAUSE > +instructions. If the instruction causes a delay, the amount of > +time delayed is called here the physical delay. The physical delay is > +first computed by determining the virtual delay (the time to delay > +relative to the VM’s timestamp counter). Otherwise, UMONITOR, UMWAIT > +and TPAUSE cause an invalid-opcode exception(#UD). > + There is no need to make it a capability. You can just check the guest CPUID and see if it includes X86_FEATURE_WAITPKG. Paolo
