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

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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.

+	case KVM_REG_PPC_TLB0CFG:
+	case KVM_REG_PPC_TLB1CFG:
+	case KVM_REG_PPC_TLB2CFG:
+	case KVM_REG_PPC_TLB3CFG: {
+ u32 tlbncfg = set_reg_val(id, *val);
+		u32 geometry_mask = TLBnCFG_N_ENTRY | TLBnCFG_ASSOC;
+		i = id - KVM_REG_PPC_TLB0CFG;
+
+ /* MMU geometry (way/size) can be set only using SW_TLB */
+		if ((vcpu->arch.tlbcfg[i] & geometry_mask) !=
+		    (tlbncfg & geometry_mask))
+			r = -EINVAL;
+
+		vcpu->arch.tlbcfg[i] = set_reg_val(id, *val);
+		break;
+	}

Likewise -- just because QEMU sets a bit here doesn't mean KVM can support it.

I thought the initial plan for setting these config registers was to accept it if it exactly matches what KVM already has, and give an error otherwise -- thus allowing for the possibliity of accepting certain specific updates in the future.

-Scott
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