Hi Paul, On Mon, Jun 17, 2019 at 12:06:32PM +1000, Paul Mackerras wrote: > The thing we need to consider is that when SMFCTRL[E] = 0, a ucall > instruction becomes a hcall (that is, sc 2 is executed as if it was > sc 1). In that case, the first argument to the ucall will be > interpreted as the hcall number. Mostly that will happen not to be a > valid hcall number, but sometimes it might unavoidably be a valid but > unintended hcall number. Shouldn't a caller of the ultravisor *know* that it is talking to the ultravisor in the first place? And not to the hypervisor. Segher
