[PATCH] KVM: PPC: e500: Expose MMU registers via ONE_REG

[Caraman Mihai Claudiu-B02008]

> -----Original Message-----
> From: Alexander Graf [mailto:agraf at suse.de]
> Sent: Thursday, March 21, 2013 12:07 PM
> To: Wood Scott-B07421
> Cc: Caraman Mihai Claudiu-B02008; kvm-ppc at vger.kernel.org; linuxppc-
> dev at lists.ozlabs.org; kvm at vger.kernel.org
> Subject: Re: [PATCH] KVM: PPC: e500: Expose MMU registers via ONE_REG
> 
> 
> On 19.03.2013, at 18:26, Scott Wood wrote:
> 
> > On 03/19/2013 12:17:11 PM, Mihai Caraman wrote:
> >> diff --git a/arch/powerpc/kvm/e500_mmu.c b/arch/powerpc/kvm/e500_mmu.c
> >> index 66b6e31..b77b855 100644
> >> --- a/arch/powerpc/kvm/e500_mmu.c
> >> +++ b/arch/powerpc/kvm/e500_mmu.c
> >> @@ -596,6 +596,95 @@ int kvmppc_set_sregs_e500_tlb(struct kvm_vcpu
> *vcpu, struct kvm_sregs *sregs)
> >> 	return 0;
> >> }
> >> +int kvmppc_get_one_reg_500_tlb(struct kvm_vcpu *vcpu, u64 id,
> >> +				union kvmppc_one_reg *val)
> >
> > s/500/e500/
> >
> >> +int kvmppc_set_one_reg_500_tlb(struct kvm_vcpu *vcpu, u64 id,
> >> +			       union kvmppc_one_reg *val)
> >> +{
> >> +	int r = 0;
> >> +	long int i;
> >> +
> >> +	switch (id) {
> >> +	case KVM_REG_PPC_MAS0:
> >> +		vcpu->arch.shared->mas0 = set_reg_val(id, *val);
> >> +		break;
> >> +	case KVM_REG_PPC_MAS1:
> >> +		vcpu->arch.shared->mas1 = set_reg_val(id, *val);
> >> +		break;
> >> +	case KVM_REG_PPC_MAS2:
> >> +		vcpu->arch.shared->mas2 = set_reg_val(id, *val);
> >> +		break;
> >> +	case KVM_REG_PPC_MAS7_3:
> >> +		vcpu->arch.shared->mas7_3 = set_reg_val(id, *val);
> >> +		break;
> >> +	case KVM_REG_PPC_MAS4:
> >> +		vcpu->arch.shared->mas4 = set_reg_val(id, *val);
> >> +		break;
> >> +	case KVM_REG_PPC_MAS6:
> >> +		vcpu->arch.shared->mas6 = set_reg_val(id, *val);
> >> +		break;
> >> +	case KVM_REG_PPC_MMUCFG: {
> >> +		u32 mmucfg = set_reg_val(id, *val);
> >> +		vcpu->arch.mmucfg = mmucfg & ~MMUCFG_LPIDSIZE;
> >> +		break;
> >> +	}
> >
> > Do we really want to allow arbitrary MMUCFG changes?  It won't
> magically make us able to support larger RAs, PIDs, different MAVN, etc.

Not magically, some changes e.g TLBnCFG_IND or TLBnPS require just a kvm
check other changes e.g. TLBnCFG_MAVN require additional support and we
might not implement all of them. Until then this code should do the job:

	/* MMU registers can be set only to the configuration supported by KVM */
	case KVM_REG_PPC_MMUCFG: {
		if (set_reg_val(id, *val) != vcpu->arch.mmucfg)
			r = -EINVAL;
		break;
	}

> 
> Only if we update the actual shadow mmu configuration as well.

These registers (MMUCFG, EPTCFG, TLBnCFG, TLBnPS) are read-only (and shared
between e6500 threads), we can only emulate them.

-Mike