From: David Gibson <david@gibson.dropbear.id.au>
To: Alexander Graf <agraf@suse.de>
Cc: lvivier@redhat.com, thuth@redhat.com, aik@ozlabs.ru,
qemu-devel@nongnu.org, qemu-ppc@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 00/10] Clean up page size handling for ppc 64-bit hash MMUs with TCG
Date: Tue, 26 Jan 2016 16:41:29 +1100 [thread overview]
Message-ID: <20160126054129.GB16692@voom.fritz.box> (raw)
In-Reply-To: <56A68758.8090805@suse.de>
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On Mon, Jan 25, 2016 at 09:36:40PM +0100, Alexander Graf wrote:
>
>
> On 01/25/2016 12:10 PM, David Gibson wrote:
> >On Mon, Jan 25, 2016 at 04:15:42PM +1100, David Gibson wrote:
> >>Encoding of page sizes on 64-bit hash MMUs for Power is rather arcane,
> >>involving control bits in both the SLB and HPTE. At present we
> >>support a few of the options, but far fewer than real hardware.
> >>
> >>We're able to get away with that in practice, because guests use a
> >>device tree property to determine which page sizes are available and
> >>we are setting that to match. However, the fact that the actual code
> >>doesn't necessarily what we put into the table of available page sizes
> >>is another ugliness.
> >>
> >>This series makes a number of cleanups to the page size handling. The
> >>upshot is that afterwards the softmmu code operates off the same page
> >>size encoding table that is advertised to the guests, ensuring that
> >>they will be in sync.
> >>
> >>Finally, we extend the table of allowed sizes for POWER7 and POWER8 to
> >>include the options allowed in hardware (including MPSS). We can fix
> >>other hash MMU based CPUs in future if anyone cares enough.
> >>
> >>Please review, and I'll fold into ppc-for-2.6 for my next pull.
> >Bother, somehow missed a serious bug in here that's causing
> >oops-on-boot. Sorry, still tracking it down.
>
> I still have no idea where your bug is (bisect probably should get you there
> pretty quick),
Alas, no, because the bug only triggers once all the page sizes are
added for POWER8 in the last patch.
Luckily I found it anyway (see earlier reply).
> but the overall concept sounds very reasonable to me. Please
> benchmark performance before and after in the next cover letter also
> :)
Hrm.. as always the question is what benchmark?
>
> Reviewed-by: Alexander Graf <agraf@suse.de>
>
> Alex
>
--
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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next prev parent reply other threads:[~2016-01-26 5:50 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 5:15 [Qemu-devel] [PATCH 00/10] Clean up page size handling for ppc 64-bit hash MMUs with TCG David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 01/10] target-ppc: Remove unused kvmppc_read_segment_page_sizes() stub David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 02/10] target-ppc: Convert mmu-hash{32, 64}.[ch] from CPUPPCState to PowerPCCPU David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 03/10] target-ppc: Rework ppc_store_slb David Gibson
2016-01-25 19:22 ` Alexander Graf
2016-01-27 0:04 ` David Gibson
2016-01-27 7:32 ` Thomas Huth
2016-01-27 10:07 ` David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 04/10] target-ppc: Rework SLB page size lookup David Gibson
2016-01-25 19:38 ` Alexander Graf
2016-01-27 0:59 ` David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 05/10] target-ppc: Use actual page size encodings from HPTE David Gibson
2016-01-25 13:26 ` David Gibson
2016-01-25 20:18 ` Alexander Graf
2016-01-27 0:40 ` David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 06/10] target-ppc: Remove unused mmu models from ppc_tlb_invalidate_one David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 07/10] target-ppc: Split 44x tlbiva from ppc_tlb_invalidate_one() David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 08/10] target-ppc: Add new TLB invalidate by HPTE call for hash64 MMUs David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 09/10] target-ppc: Helper to determine page size information from hpte alone David Gibson
2016-01-25 5:15 ` [Qemu-devel] [PATCH 10/10] target-ppc: Allow more page sizes for POWER7 & POWER8 in TCG David Gibson
2016-01-25 11:10 ` [Qemu-devel] [PATCH 00/10] Clean up page size handling for ppc 64-bit hash MMUs with TCG David Gibson
2016-01-25 20:36 ` Alexander Graf
2016-01-26 5:41 ` David Gibson [this message]
2016-01-26 7:09 ` Alexander Graf
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