On Wed, 21 Sep 2016 07:45:35 +1000
Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote:
> On Tue, 2016-09-20 at 13:44 +0200, Thomas Huth wrote:
> >
> > Seems like KVM PR is using the "degraded" ISA variants (without the
> > 1TB
> > segments), but the new POWERPC_MMU_64K flag has not been added to
> > those.
> > Has this been done on purpose, or was this just by accident?
> > I can make KVM PR working again with the following patch:
> >
> > diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
> > index 2864105..36694cb 100644
> > --- a/target-ppc/cpu-qom.h
> > +++ b/target-ppc/cpu-qom.h
> > @@ -81,6 +81,7 @@ enum powerpc_mmu_t {
> > | POWERPC_MMU_AMR | 0x00000003,
> > /* Architecture 2.06 "degraded" (no 1T segments) */
> > POWERPC_MMU_2_06a = POWERPC_MMU_64 | POWERPC_MMU_AMR
> > + | POWERPC_MMU_64K
> > | 0x00000003,
> > /* Architecture 2.07 variant */
> > POWERPC_MMU_2_07 = POWERPC_MMU_64 | POWERPC_MMU_1TSEG
> > @@ -88,6 +89,7 @@ enum powerpc_mmu_t {
> > | POWERPC_MMU_AMR | 0x00000004,
> > /* Architecture 2.07 "degraded" (no 1T segments) */
> > POWERPC_MMU_2_07a = POWERPC_MMU_64 | POWERPC_MMU_AMR
> > + | POWERPC_MMU_64K
> > | 0x00000004,
> > };
> >
> > However, not sure whether this is the right fix ... Cédric, Ben, any
> > ideas?
>
> Oh I thought I had removed the degraded variants ... Definitely looks
> like an accident. I *think* PR KVM supports 64K pages, no ? If not,
> then we shouldn't enable the flag.. somebody needs to check the kernel.
Yes, it supports 64k pages - but only on POWER8, not on POWER8E or
POWER8NVL yet. I've posted a patch to fix this here:
https://patchwork.ozlabs.org/patch/672841/
Thomas
