On Fri, Feb 07, 2020 at 01:54:26AM -0500, Michael S. Tsirkin wrote: > On Fri, Feb 07, 2020 at 03:30:54PM +1100, David Gibson wrote: > > PAPR specifies a kind of odd, paravirtualized PCI bus, which looks to > > the guess mostly like classic PCI, even if some of the individual > > devices on the bus are PCI Express. One consequence of that is that > > virtio-pci devices still default to being in transitional mode, though > > legacy mode is now disabled by default on current q35 x86 machine > > types. > > > > Legacy mode virtio devices aren't really necessary any more, and are > > causing some problems for future changes. Therefore, for the > > pseries-5.0 machine type (and onwards), switch to modern-only > > virtio-pci devices by default. > > It's worth noting in the commit log that this disables support > for guests older than Linux 4.0.
Oof. That's more recent than I'd guessed. I'll have to do some
checking to see if that's reasonable.
>
> >
> > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
> > ---
> > hw/ppc/spapr.c | 14 +++++++++++++-
> > 1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index c9b2e0a5e0..216d3b34dc 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -65,6 +65,7 @@
> >
> > #include "hw/pci/pci.h"
> > #include "hw/scsi/scsi.h"
> > +#include "hw/virtio/virtio-pci.h"
> > #include "hw/virtio/virtio-scsi.h"
> > #include "hw/virtio/vhost-scsi-common.h"
> >
> > @@ -4512,7 +4513,14 @@ static const TypeInfo spapr_machine_info = {
> > */
> > static void spapr_machine_5_0_class_options(MachineClass *mc)
> > {
> > - /* Defaults for the latest behaviour inherited from the base class */
> > + /* Most defaults for the latest behaviour are inherited from the
> > + * base class, but we need to override the (non ppc specific)
> > + * default behaviour for virtio */
> > + static GlobalProperty compat[] = {
> > + { TYPE_VIRTIO_PCI, "disable-legacy", "on", },
> > + };
> > +
> > + compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));
> > }
> >
> > DEFINE_SPAPR_MACHINE(5_0, "5.0", true);
>
> So this sets the defaults, right?
>
> Problem is we'll then need to remember to carry this in the latest
> call. If we forget we get a mess.
>
> How about adding a call to e.g. spapr_machine_latest_class_options
> in DEFINE_SPAPR_MACHINE?
> Then spapr_machine_latest_class_options can set the per-machine
> defaults.
>
> I send a patch for this:
> [PATCH] ppc: function to setup latest class options
> feel free to reuse.
Good idea, thanks. I've merged that and will rebase these changes on it.
>
>
> > @@ -4523,11 +4531,15 @@ DEFINE_SPAPR_MACHINE(5_0, "5.0", true);
> > static void spapr_machine_4_2_class_options(MachineClass *mc)
> > {
> > SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> > + static GlobalProperty compat[] = {
> > + { TYPE_VIRTIO_PCI, "disable-legacy", "auto" },
> > + };
> >
> > spapr_machine_5_0_class_options(mc);
> > compat_props_add(mc->compat_props, hw_compat_4_2, hw_compat_4_2_len);
> > smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_OFF;
> > smc->default_caps.caps[SPAPR_CAP_FWNMI_MCE] = SPAPR_CAP_OFF;
> > + compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));
> > }
> >
> > DEFINE_SPAPR_MACHINE(4_2, "4.2", false);
>
--
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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