On Thu, Jan 04, 2018 at 06:47:18PM +0100, Greg Kurz wrote:
> On Thu, 4 Jan 2018 15:24:05 +1100
> David Gibson <da...@gibson.dropbear.id.au> wrote:
>
> > Currently the pseries machine sets the compatibility mode for the
> > guest's cpus in two places: 1) at machine reset and 2) after CAS
> > negotiation.
> >
> > This means that if we set or negotiate a compatiblity mode, then
> > hotplug a cpu, the hotplugged cpu doesn't get the right mode set and
> > will incorrectly have the full native features.
> >
> > To correct this, we set the compatibility mode on a cpu when it is
> > brought online with the 'start-cpu' RTAS call. Given that we no
> > longer need to set the compatibility mode on all CPUs at machine
> > reset, so we change that to only set the mode for the boot cpu.
> >
> > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
> > ---
> > hw/ppc/spapr.c | 2 +-
> > hw/ppc/spapr_rtas.c | 8 ++++++++
> > 2 files changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index e22888ba06..d1acfe8858 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1510,7 +1510,7 @@ static void spapr_machine_reset(void)
> > spapr_ovec_cleanup(spapr->ov5_cas);
> > spapr->ov5_cas = spapr_ovec_new();
> >
> > - ppc_set_compat_all(spapr->max_compat_pvr, &error_fatal);
> > + ppc_set_compat(first_ppc_cpu, spapr->max_compat_pvr, &error_fatal);
> > }
> >
> > fdt = spapr_build_fdt(spapr, rtas_addr, spapr->rtas_size);
> > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> > index 4bb939d3d1..2ed00548c1 100644
> > --- a/hw/ppc/spapr_rtas.c
> > +++ b/hw/ppc/spapr_rtas.c
> > @@ -163,6 +163,7 @@ static void rtas_start_cpu(PowerPCCPU *cpu_,
> > sPAPRMachineState *spapr,
> > CPUState *cs = CPU(cpu);
> > CPUPPCState *env = &cpu->env;
> > PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> > + Error *local_err = NULL;
> >
> > if (!cs->halted) {
> > rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
> > @@ -174,6 +175,13 @@ static void rtas_start_cpu(PowerPCCPU *cpu_,
> > sPAPRMachineState *spapr,
> > * new cpu enters */
> > kvm_cpu_synchronize_state(cs);
> >
> > + /* Set compatibility mode to match existing cpus */
> > + ppc_set_compat(cpu, POWERPC_CPU(first_cpu)->compat_pvr,
> > &local_err);
>
> Is it okay to report a simple HW error to the guest here instead of aborting
> like we do with first_cpu at reset time ?
Should be: this happens before we turn the cpu on, so the effect will
be that the guest fails to online the cpu. That seems like a better
failure mode than killing the already running guest.
>
> > + if (local_err) {
> > + rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
> > + return;
> > + }
> > +
> > env->msr = (1ULL << MSR_SF) | (1ULL << MSR_ME);
> >
> > /* Enable Power-saving mode Exit Cause exceptions for the new CPU
> > */
>
--
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
signature.asc
Description: PGP signature
