[PATCH 1/5] KVM: PPC: e500: Move VCPU's MMUCFG register initialization earlier

[Caraman Mihai Claudiu-B02008]

> -----Original Message-----
> From: Alexander Graf [mailto:agraf at suse.de]
> Sent: Thursday, January 31, 2013 4:58 PM
> To: Caraman Mihai Claudiu-B02008
> Cc: kvm-ppc at vger.kernel.org; kvm at vger.kernel.org; linuxppc-
> dev at lists.ozlabs.org
> Subject: Re: [PATCH 1/5] KVM: PPC: e500: Move VCPU's MMUCFG register
> initialization earlier
> 
> 
> On 31.01.2013, at 15:56, Caraman Mihai Claudiu-B02008 wrote:
> 
> >> -----Original Message-----
> >> From: Alexander Graf [mailto:agraf at suse.de]
> >> Sent: Thursday, January 31, 2013 3:21 PM
> >> To: Caraman Mihai Claudiu-B02008
> >> Cc: kvm-ppc at vger.kernel.org; kvm at vger.kernel.org; linuxppc-
> >> dev at lists.ozlabs.org
> >> Subject: Re: [PATCH 1/5] KVM: PPC: e500: Move VCPU's MMUCFG register
> >> initialization earlier
> >>
> >>
> >> On 30.01.2013, at 14:29, Mihai Caraman wrote:
> >>
> >>> VCPU's MMUCFG register initialization should not depend on
> >> KVM_CAP_SW_TLB
> >>> ioctl call. Move it earlier into tlb initalization phase.
> >>
> >> Quite the contrary. The fact that there is an mfspr() in e500_mmu.c
> >> already tells us that the code is broken. The TLB guest code should
> only
> >> depend on input from the SW_TLB configuration. It's completely
> orthogonal
> >> to the host capabilities.
> >
> > Then we have the same issue for TLBnCFG registers which need to be
> configured
> > via SW_TLB ioctl. What is the purpose of guest tlb initalization in
> e500_mmu.c
> > if we rely on SW_TLB?
> 
> It's to provide a fallback to user space that doesn't implement SW_TLB
> configuration yet.

Do we have such a case now or is it just hypothetical? For the fallback we
need to initialize the MMUCFG register which I intended to say in the commit
message.

> 
> 
> Alex
>