On Mon, 14 Oct 2019 17:12:47 +1100 David Gibson <da...@gibson.dropbear.id.au> wrote:
> On Thu, Oct 03, 2019 at 02:02:00PM +0200, Greg Kurz wrote:
> > Support for setting VSMT is available in KVM since linux-4.13. Most distros
> > that support KVM on POWER already have it. It thus seem reasonable enough
> > to have the default machine to set VSMT to smp_threads.
> >
> > This brings contiguous VCPU ids and thus brings their upper bound down to
> > the machine's max_cpus. This is especially useful for XIVE KVM devices,
> > which may thus allocate only one VP descriptor per VCPU.
> >
Just to clarify that without the other patches in this series, XIVE
KVM devices still allocate a fixed block of 2048 VPs, no matter what.
ie, the last sentence in the changelog may be slightly misleading.
> > Signed-off-by: Greg Kurz <gr...@kaod.org>
>
> Applied to ppc-for-4.2, thanks.
>
> > ---
> > hw/ppc/spapr.c | 7 ++++++-
> > include/hw/ppc/spapr.h | 1 +
> > 2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 8f59f08c102e..473ce1d04775 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -2503,6 +2503,7 @@ static CPUArchId *spapr_find_cpu_slot(MachineState
> > *ms, uint32_t id, int *idx)
> > static void spapr_set_vsmt_mode(SpaprMachineState *spapr, Error **errp)
> > {
> > MachineState *ms = MACHINE(spapr);
> > + SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
> > Error *local_err = NULL;
> > bool vsmt_user = !!spapr->vsmt;
> > int kvm_smt = kvmppc_smt_threads();
> > @@ -2529,7 +2530,7 @@ static void spapr_set_vsmt_mode(SpaprMachineState
> > *spapr, Error **errp)
> > goto out;
> > }
> > /* In this case, spapr->vsmt has been set by the command line */
> > - } else {
> > + } else if (!smc->smp_threads_vsmt) {
> > /*
> > * Default VSMT value is tricky, because we need it to be as
> > * consistent as possible (for migration), but this requires
> > @@ -2538,6 +2539,8 @@ static void spapr_set_vsmt_mode(SpaprMachineState
> > *spapr, Error **errp)
> > * overwhelmingly common case in production systems.
> > */
> > spapr->vsmt = MAX(8, smp_threads);
> > + } else {
> > + spapr->vsmt = smp_threads;
> > }
> >
> > /* KVM: If necessary, set the SMT mode: */
> > @@ -4452,6 +4455,7 @@ static void spapr_machine_class_init(ObjectClass *oc,
> > void *data)
> > smc->irq = &spapr_irq_dual;
> > smc->dr_phb_enabled = true;
> > smc->linux_pci_probe = true;
> > + smc->smp_threads_vsmt = true;
> > }
> >
> > static const TypeInfo spapr_machine_info = {
> > @@ -4519,6 +4523,7 @@ static void
> > spapr_machine_4_1_class_options(MachineClass *mc)
> >
> > spapr_machine_4_2_class_options(mc);
> > smc->linux_pci_probe = false;
> > + smc->smp_threads_vsmt = false;
> > compat_props_add(mc->compat_props, hw_compat_4_1, hw_compat_4_1_len);
> > compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));
> > }
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index cbd1a4c9f390..2009eb64f9cb 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -122,6 +122,7 @@ struct SpaprMachineClass {
> > bool broken_host_serial_model; /* present real host info to the guest
> > */
> > bool pre_4_1_migration; /* don't migrate hpt-max-page-size */
> > bool linux_pci_probe;
> > + bool smp_threads_vsmt; /* set VSMT to smp_threads by default */
> >
> > void (*phb_placement)(SpaprMachineState *spapr, uint32_t index,
> > uint64_t *buid, hwaddr *pio,
> >
>
pgpd46JSWO6tD.pgp
Description: OpenPGP digital signature
