On Fri, Oct 28, 2016 at 11:32:43AM +0200, Greg Kurz wrote: > On Fri, 28 Oct 2016 13:05:01 +1100 > David Gibson <da...@gibson.dropbear.id.au> wrote: > > > powernv has some code (derived from the spapr equivalent) used in device > > tree generation which depends on the CPU's compatibility mode / logical > > PVR. However, compatibility modes don't make sense on powernv - at least > > not as a property controlled by the host - because the guest in powernv > > has full hypervisor level access to the virtual system, and so owns the > > PCR (Processor Compatibility Register) which implements compatiblity modes. > > > > This makes a lot of sense indeed. > > > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> > > --- > > hw/ppc/pnv.c | 6 +----- > > 1 file changed, 1 insertion(+), 5 deletions(-) > > > > Hi Cédric, I'd appreciate it if you can double check my reasoning > > here. This patch gets powernv out of the way of a bunch of > > compatibility mode cleanups I have in the works. > > > > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c > > index 82276e0..6af3424 100644 > > --- a/hw/ppc/pnv.c > > +++ b/hw/ppc/pnv.c > > @@ -110,7 +110,7 @@ static void powernv_create_core_node(PnvChip *chip, > > PnvCore *pc, void *fdt) > > CPUState *cs = CPU(DEVICE(pc->threads)); > > DeviceClass *dc = DEVICE_GET_CLASS(cs); > > PowerPCCPU *cpu = POWERPC_CPU(cs); > > - int smt_threads = ppc_get_compat_smt_threads(cpu); > > + int smt_threads = CPU_CORE(pc)->nr_threads; > > Not speaking of the PCR, this has also another effect since > ppc_get_compat_smt_threads() also take the KVM smt capability > into account: > > int ret = MIN(cs->nr_threads, kvmppc_smt_threads()); > > Shouldn't you do the same here ?
Actually, no, though possible that needs mention in the commit
message. I'm pretty sure there are checks elsewhere that ensure
nr_threads <= kvmppc_smt_threads(). If not, having more virtual
threads than kvmppc allows certainly can't work, so we're no more
broken than before.
Plus, kvmppc_smt_threads() is really only relevant for KVM HV which
doesn't, and can't support the powernv machine type anyway.
--
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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