RE: [PATCH v2] powerpc/fsl-booke: declare tlbcam_index for use inc file

-----Original Message-----
From: kvm-ppc-owner@vger.kernel.org=20
[mailto:kvm-ppc-owner@vger.kernel.org] On Behalf Of Hollis Blanchard
Sent: Tuesday, January 06, 2009 12:52 AM
To: Gala Kumar-B11780
Cc: Liu Yu-B13201; kvm-ppc@vger.kernel.org;=20
linuxppc-dev@ozlabs.org; Piepho Trent-B16872; Wood Scott-B07421
Subject: Re: [PATCH v2] powerpc/fsl-booke: declare=20
tlbcam_index for use inc file
=20
On Mon, 2009-01-05 at 10:26 -0600, Kumar Gala wrote:

quoted

I'll pick this up, but wondering about this patch vs=20

Trent's changes =20

quoted

to remove this.

=20
Please do not pick up this patch; if you ack it, let us push=20
it through
kvm.git. Otherwise we need to wait for it to travel from kumar.git ->
benh.git -> linus.git -> kvm.git before KVM will build.
=20
If you're referring to http://patchwork.ozlabs.org/patch/12882/, that
patch removes a different variable (num_tlbcam_entries). tlbcam_index,
referenced below, still exists.

Since v2 has removed the num_tlbcam_entries declare, this patch has no
conflict with Trent's changes.

=20

quoted

How is KVM on fsl-booke using this value?

=20
I'll let Yu answer that in more detail, but in
http://git.kernel.org/?p=3Dlinux/kernel/git/avi/kvm.git;a=3Dblob_p

lain;f=3Darch/powerpc/kvm/e500_tlb.c;hb=3DHEAD it looks like he's =
storing >
guest TLB1 mappings in the real TLB1, alongside the host TLB1=20

mappings. Accordingly, he needs to know where the host=20
mappings are to avoid clobbering them.

Yes, just like Hollis described.
KVM only read tlbcam_index to know which entries are used by host.
And kvm assumes the value is fixed and will never change it.

=20

quoted

On Jan 4, 2009, at 12:57 AM, Liu Yu wrote:
=20

quoted

Hi Kumar,

Can I get your ack?
So that I can submit this patch through KVM tree.

quoted

-----Original Message-----
From: Liu Yu-B13201
Sent: Friday, December 19, 2008 10:35 AM
To: kvm-ppc@vger.kernel.org; linuxppc-dev@ozlabs.org
Cc: hollisb@us.ibm.com; Gala Kumar-B11780; Piepho
Trent-B16872; Wood Scott-B07421; Liu Yu-B13201
Subject: [PATCH v2] powerpc/fsl-booke: declare tlbcam_index
for use in c file

KVM on E500 platform currently utilize TLB1 entries without
bothering host,
that is using unused TLB1 entries.

So, KVM needs to read tlbcam_index to know exactly
which TLB1 entry is unused by host.

Signed-off-by: Liu Yu <redacted>
---
[v2]
Remove num_tlbcam_entries declare and read from SPRN_TLB1CFG
in KVM instead.

arch/powerpc/include/asm/mmu-fsl-booke.h |    2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu-fsl-booke.h

b/arch/powerpc/include/asm/mmu-fsl-booke.h
index 925d93c..c86af6c 100644

--- a/arch/powerpc/include/asm/mmu-fsl-booke.h
+++ b/arch/powerpc/include/asm/mmu-fsl-booke.h

@@ -73,6 +73,8 @@

#ifndef __ASSEMBLY__

+extern unsigned int tlbcam_index;
+
typedef struct {
	unsigned long id;
	unsigned long vdso_base;
--=20
1.5.4

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=20

--=20
Hollis Blanchard
IBM Linux Technology Center
=20
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