From: Benjamin Herrenschmidt <benh@au1•ibm.com>
To: Michael Ellerman <mpe@ellerman•id.au>,
Nicholas Piggin <npiggin@gmail•com>,
linuxppc-dev@lists•ozlabs.org
Cc: Suraj Jitindar Singh <surajjs@ozlabs•au.ibm.com>,
kvm-ppc@vger•kernel.org, aneesh.kumar@linux•vnet.ibm.com
Subject: Re: [PATCH v2 3/9] powerpc/powernv: Remove real mode access limit for early allocations
Date: Mon, 14 Aug 2017 23:10:50 +1000 [thread overview]
Message-ID: <1502716250.4493.25.camel@au1.ibm.com> (raw)
In-Reply-To: <87h8xaqpp8.fsf@concordia.ellerman.id.au>
On Mon, 2017-08-14 at 22:49 +1000, Michael Ellerman wrote:
> Nicholas Piggin <npiggin@gmail•com> writes:
>
> > This removes the RMA limit on powernv platform, which constrains
> > early allocations such as PACAs and stacks. There are still other
> > restrictions that must be followed, such as bolted SLB limits, but
> > real mode addressing has no constraints.
For radix, should we consider making the PACAs chip/node local ?
> > Signed-off-by: Nicholas Piggin <npiggin@gmail•com>
> > ---
> > arch/powerpc/mm/hash_utils_64.c | 24 +++++++++++++++---------
> > arch/powerpc/mm/pgtable-radix.c | 33 +++++++++++++++++----------------
>
> I missed that we'd duplicated this logic for radix vs hash [yes I know I
> merged the commit that did it :)]
>
> > diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
> > index 671a45d86c18..61ca17d81737 100644
> > --- a/arch/powerpc/mm/pgtable-radix.c
> > +++ b/arch/powerpc/mm/pgtable-radix.c
> > @@ -598,22 +598,23 @@ void radix__setup_initial_memory_limit(phys_addr_t first_memblock_base,
> > * physical on those processors
> > */
> > BUG_ON(first_memblock_base != 0);
> > - /*
> > - * We limit the allocation that depend on ppc64_rma_size
> > - * to first_memblock_size. We also clamp it to 1GB to
> > - * avoid some funky things such as RTAS bugs.
>
> That comment about RTAS is 7 years old, and I'm pretty sure it was a
> historical note when it was written.
>
> I'm inclined to drop it and if we discover new bugs with RTAS on Power9
> then we can always put it back.
>
> > - *
> > - * On radix config we really don't have a limitation
> > - * on real mode access. But keeping it as above works
> > - * well enough.
>
> Ergh.
>
> > - */
> > - ppc64_rma_size = min_t(u64, first_memblock_size, 0x40000000);
> > - /*
> > - * Finally limit subsequent allocations. We really don't want
> > - * to limit the memblock allocations to rma_size. FIXME!! should
> > - * we even limit at all ?
> > - */
>
> So I think we should just delete this function entirely.
>
> Any objections?
>
> cheers
next prev parent reply other threads:[~2017-08-14 13:11 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-12 11:34 [PATCH v2 0/9] improve early structure allocations (paca, lppaca, etc) Nicholas Piggin
2017-08-13 1:33 ` [PATCH v2 1/9] KVM: PPC: Book3S HV: Fix H_REGISTER_VPA VPA size validation Nicholas Piggin
2017-08-15 11:24 ` Michael Ellerman
2017-08-31 3:41 ` Paul Mackerras
2017-08-13 1:33 ` [PATCH v2 2/9] powerpc/powernv: powernv platform is not constrained by RMA Nicholas Piggin
2017-08-31 11:36 ` [v2, " Michael Ellerman
2017-08-13 1:33 ` [PATCH v2 3/9] powerpc/powernv: Remove real mode access limit for early allocations Nicholas Piggin
2017-08-14 12:49 ` Michael Ellerman
2017-08-14 13:10 ` Benjamin Herrenschmidt [this message]
2017-08-14 14:51 ` Nicholas Piggin
2017-08-14 13:13 ` Benjamin Herrenschmidt
2017-08-15 12:10 ` Nicholas Piggin
2017-08-15 12:48 ` Benjamin Herrenschmidt
2017-08-15 13:02 ` Nicholas Piggin
2017-09-12 10:13 ` Aneesh Kumar K.V
2017-09-12 10:26 ` Benjamin Herrenschmidt
2017-08-13 1:33 ` [PATCH v2 4/9] powerpc/64s/radix: Remove bolted-SLB address limit for per-cpu stacks Nicholas Piggin
2017-08-31 11:36 ` [v2, " Michael Ellerman
2017-08-13 1:33 ` [PATCH v2 5/9] powerpc/64s: Relax PACA address limitations Nicholas Piggin
2017-08-13 1:33 ` [PATCH v2 6/9] powerpc/64s/radix: Do not allocate SLB shadow structures Nicholas Piggin
2017-08-31 11:36 ` [v2, " Michael Ellerman
2017-08-13 1:33 ` [PATCH v2 7/9] powerpc/64s: do not allocate lppaca if we are not virtualized Nicholas Piggin
2017-10-13 22:47 ` Paul Mackerras
2017-10-14 3:54 ` Nicholas Piggin
2017-08-13 1:33 ` [PATCH v2 8/9] powerpc/64: Use a table of paca pointers and allocate pacas individually Nicholas Piggin
2017-08-15 15:50 ` Nicholas Piggin
2017-08-15 17:30 ` kbuild test robot
2017-08-13 1:33 ` [PATCH v2 9/9] powerpc/64: Use a table of lppaca pointers and allocate lppacas individually Nicholas Piggin
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