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

[Liu Yu]

> -----Original Message-----
> From: kvm-ppc-owner at vger.kernel.org 
> [mailto:kvm-ppc-owner at 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 at vger.kernel.org; 
> linuxppc-dev at ozlabs.org; Piepho Trent-B16872; Wood Scott-B07421
> Subject: Re: [PATCH v2] powerpc/fsl-booke: declare 
> tlbcam_index for use inc file
> 
> On Mon, 2009-01-05 at 10:26 -0600, Kumar Gala wrote:
> > I'll pick this up, but wondering about this patch vs 
> Trent's changes  
> > to remove this.
> 
> Please do not pick up this patch; if you ack it, let us push 
> 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.
> 
> 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.

> 
> > How is KVM on fsl-booke using this value?
> 
> I'll let Yu answer that in more detail, but in
> http://git.kernel.org/?p=linux/kernel/git/avi/kvm.git;a=blob_p
lain;f=arch/powerpc/kvm/e500_tlb.c;hb=HEAD it looks like he's storing >
guest TLB1 mappings in the real TLB1, alongside the host TLB1 
> mappings. Accordingly, he needs to know where the host 
> 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.

> 
> > On Jan 4, 2009, at 12:57 AM, Liu Yu wrote:
> > 
> > > Hi Kumar,
> > >
> > > Can I get your ack?
> > > So that I can submit this patch through KVM tree.
> > >
> > >
> > >> -----Original Message-----
> > >> From: Liu Yu-B13201
> > >> Sent: Friday, December 19, 2008 10:35 AM
> > >> To: kvm-ppc at vger.kernel.org; linuxppc-dev at ozlabs.org
> > >> Cc: hollisb at 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 <yu.liu at freescale.com>
> > >> ---
> > >> [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;
> > >> -- 
> > >> 1.5.4
> > >>
> > >>
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe 
> kvm-ppc" in
> > > the body of a message to majordomo at vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> -- 
> Hollis Blanchard
> IBM Linux Technology Center
> 
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>