On Fri, Apr 06, 2018 at 04:12:32PM +1000, Michael Ellerman wrote:
> Nicholas Piggin <npiggin@xxxxxxxxx> writes:
> > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> > index 78e6a392330f..0221a0f74f07 100644
> > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> > @@ -439,6 +439,9 @@ static inline int try_lock_tlbie(unsigned int *lock)
> > unsigned int tmp, old;
> > unsigned int token = LOCK_TOKEN;
> >
> > + if (mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE))
> > + return 1;
> > +
> > asm volatile("1:lwarx %1,0,%2\n"
> > " cmpwi cr0,%1,0\n"
> > " bne 2f\n"
> > @@ -452,6 +455,12 @@ static inline int try_lock_tlbie(unsigned int *lock)
> > return old == 0;
> > }
> >
> > +static inline void unlock_tlbie_after_sync(unsigned int *lock)
> > +{
> > + if (mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE))
> > + return;
> > +}
>
> So this is a bit hard to follow:
>
> #define MMU_FTRS_DEFAULT_HPTE_ARCH_V2 \
> MMU_FTR_HPTE_TABLE | MMU_FTR_PPCAS_ARCH_V2
> #define MMU_FTRS_POWER MMU_FTRS_DEFAULT_HPTE_ARCH_V2
> #define MMU_FTRS_PPC970 MMU_FTRS_POWER | MMU_FTR_TLBIE_CROP_VA // does NOT
> #define MMU_FTRS_POWER5 MMU_FTRS_POWER | MMU_FTR_LOCKLESS_TLBIE
> #define MMU_FTRS_POWER6 MMU_FTRS_POWER5 | MMU_FTR_KERNEL_RO | MMU_FTR_68_BIT_VA // includes lockless TLBIE
> #define MMU_FTRS_POWER7 MMU_FTRS_POWER6 // includes lockless TLBIE
> #define MMU_FTRS_POWER8 MMU_FTRS_POWER6 // includes lockless TLBIE
> #define MMU_FTRS_POWER9 MMU_FTRS_POWER6 // includes lockless TLBIE
> #define MMU_FTRS_CELL MMU_FTRS_DEFAULT_HPTE_ARCH_V2 | // does NOT
> MMU_FTR_CI_LARGE_PAGE
> #define MMU_FTRS_PA6T MMU_FTRS_DEFAULT_HPTE_ARCH_V2 | \ // does NOT
> MMU_FTR_CI_LARGE_PAGE | MMU_FTR_NO_SLBIE_B
>
>
> So it's only 970, Cell and Pasemi that *don't* have lockless TLBIE.
>
> And KVM HV doesn't doesn't run on any of those.
>
> So we can just not check for the feature in the KVM HV code.
>
> Am I right?
Yes; that code was written when we still supported HV KVM on 970,
but we ripped that out some time ago.
Paul.
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