Re: [Qemu-devel] [Qemu-ppc] [PATCH v3] spapr: add splpar hcalls H_PROD, H_CONFER

[Greg Kurz]

On Wed, 17 Apr 2019 21:20:00 +1000
Nicholas Piggin <address@hidden> wrote:
> [...]
> >> @@ -1860,6 +1928,9 @@ static void hypercall_register_types(void)
> >>      /* hcall-splpar */
> >>      spapr_register_hypercall(H_REGISTER_VPA, h_register_vpa);
> >>      spapr_register_hypercall(H_CEDE, h_cede);
> >> +    spapr_register_hypercall(H_CONFER, h_confer);
> >> +    spapr_register_hypercall(H_PROD, h_prod);
> >> +
> >>      spapr_register_hypercall(H_SIGNAL_SYS_RESET, h_signal_sys_reset);  
> > 
> > You're no longer enabling the KVM CONFER and PROD hypercalls.  Are
> > they enabled by default, or is that an intentional change?  
> 

AFAICT they seem to be enabled by default in HV KVM.

> Oh, it was not intentional, I must not understand how this works. Why
> is this no longer enabling the those hcalls?
> 

Since linux commit 699a0ea0823d ("KVM: PPC: Book3S: Controls for in-kernel 
sPAPR hypercall handling"), in-kernel hypercalls are disabled by default
and must be explicitely enabled by userspace. QEMU does that for some
hypercalls already (search kvmppc_enable_set_mode_hcall() in QEMU for an
example).

Since H_CONFER and H_PROD are listed in default_hcall_list[] in book3s_hv.c,
no need for QEMU to enable them in KVM.

Not sure about David's "no longer" wording though.

> Thanks,
> Nick
> 
> 

Cheers,

--
Greg