On Mon, Jul 01, 2019 at 02:23:21PM +1000, Suraj Jitindar Singh wrote: > On Fri, 2019-06-28 at 19:29 +1000, David Gibson wrote: > > On Mon, Jun 24, 2019 at 03:58:11PM +1000, Suraj Jitindar Singh wrote: > > > The hcall H_PURR is used by a guest to read the PURR (processor > > > utilisation of resources register). A guest expects that this > > > register > > > will count at a rate of timebase scaled by the number of guest > > > vcpus > > > present in the vcore. That is the per vcpu purr will count at a > > > rate of > > > timebase / # vcpus per vcore. > > > > > > Implement a handler for the H_PURR hcall and return the purr value > > > divided by smp_threads so that the sum of the purr deltas across > > > the > > > vcpus of a vcore equals the timebase delta > > > > > > Signed-off-by: Suraj Jitindar Singh <sjitindarsi...@gmail.com> > > > > Does this need something new advertised in the hypertas DT entry? > > Hi David, > > There doesn't seem to be a concensus on what the return value from the > H_PURR hcall should be, whether it just returns the hardware value or > does some adjusting of the value based on guest smt mode as I've > implemented in the patch below.
*eyeroll*. Lack of forethought in PAPR strikes again.
> As such please drop this patch series.
Ok, will do.
>
> The guest can just read the purr register directly anyway and then
> interpret the values as it pleases.
>
> Kind Regards,
> Suraj
>
> >
> > > ---
> > > hw/ppc/spapr_hcall.c | 24 ++++++++++++++++++++++++
> > > 1 file changed, 24 insertions(+)
> > >
> > > diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> > > index aae9fd2b3e..88b3343f04 100644
> > > --- a/hw/ppc/spapr_hcall.c
> > > +++ b/hw/ppc/spapr_hcall.c
> > > @@ -1819,6 +1819,27 @@ static target_ulong h_update_dt(PowerPCCPU
> > > *cpu, SpaprMachineState *spapr,
> > > return H_SUCCESS;
> > > }
> > >
> > > +static target_ulong h_purr(PowerPCCPU *cpu, SpaprMachineState
> > > *spapr,
> > > + target_ulong opcode, target_ulong
> > > *args)
> > > +{
> > > + CPUPPCState *env = &cpu->env;
> > > + target_ulong purr;
> > > +
> > > + if (kvm_enabled()) {
> > > + cpu_synchronize_state(CPU(cpu));
> > > + /*
> > > + * Divide by smp_threads so that the sum of the purr
> > > deltas across the
> > > + * vcpus of a vcore equal the timebase delta.
> > > + */
> > > + purr = env->spr[SPR_PURR] / smp_threads;
> > > + } else {
> > > + purr = cpu_ppc_load_purr(env);
> > > + }
> > > + args[0] = purr;
> > > +
> > > + return H_SUCCESS;
> > > +}
> > > +
> > > static spapr_hcall_fn papr_hypercall_table[(MAX_HCALL_OPCODE / 4)
> > > + 1];
> > > static spapr_hcall_fn kvmppc_hypercall_table[KVMPPC_HCALL_MAX -
> > > KVMPPC_HCALL_BASE + 1];
> > >
> > > @@ -1915,6 +1936,9 @@ static void hypercall_register_types(void)
> > > spapr_register_hypercall(H_LOGICAL_DCBF, h_logical_dcbf);
> > > spapr_register_hypercall(KVMPPC_H_LOGICAL_MEMOP,
> > > h_logical_memop);
> > >
> > > + /* hcall-purr */
> > > + spapr_register_hypercall(H_PURR, h_purr);
> > > +
> > > /* qemu/KVM-PPC specific hcalls */
> > > spapr_register_hypercall(KVMPPC_H_RTAS, h_rtas);
> > >
> >
> >
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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