KVM: PPC: Add sanity checking to vcpu_run

There are multiple features in PowerPC KVM that can now be enabled
depending on the user's wishes. Some of the combinations don't make
sense or don't work though.

So this patch adds a way to check if the executing environment would
actually be able to run the guest properly. It also adds sanity
checks if PVR is set (should always be true given the current code
flow), if PAPR is only used with book3s_64 where it works and that
HV KVM is only used in PAPR mode.
Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/include/asm/kvm.h

@@ -284,6 +284,11 @@ struct kvm_guest_debug_arch {
 #define KVM_INTERRUPT_UNSET	-2U
 #define KVM_INTERRUPT_SET_LEVEL	-3U
 
+#define KVM_CPU_440		1
+#define KVM_CPU_E500V2		2
+#define KVM_CPU_3S_32		3
+#define KVM_CPU_3S_64		4
+
 /* for KVM_CAP_SPAPR_TCE */
 struct kvm_create_spapr_tce {
 	__u64 liobn;

arch/powerpc/include/asm/kvm_host.h

@@ -390,6 +390,8 @@ struct kvm_vcpu_arch {
 	u8 osi_needed;
 	u8 osi_enabled;
 	u8 papr_enabled;
+	u8 sane;
+	u8 cpu_type;
 	u8 hcall_needed;
 
 	u32 cpr0_cfgaddr; /* holds the last set cpr0_cfgaddr */

arch/powerpc/include/asm/kvm_ppc.h

@@ -66,6 +66,7 @@ extern int kvmppc_emulate_instruction(struct kvm_run *run,
 extern int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu);
 extern void kvmppc_emulate_dec(struct kvm_vcpu *vcpu);
 extern u32 kvmppc_get_dec(struct kvm_vcpu *vcpu, u64 tb);
+extern int kvmppc_sanity_check(struct kvm_vcpu *vcpu);
 
 /* Core-specific hooks */
 

arch/powerpc/kvm/44x.c

@@ -78,6 +78,8 @@ int kvmppc_core_vcpu_setup(struct kvm_vcpu *vcpu)
 	for (i = 0; i < ARRAY_SIZE(vcpu_44x->shadow_refs); i++)
 		vcpu_44x->shadow_refs[i].gtlb_index = -1;
 
+	vcpu->arch.cpu_type = KVM_CPU_440;
+
 	return 0;
 }
 

arch/powerpc/kvm/book3s_hv.c

@@ -510,6 +510,9 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 	spin_unlock(&vcore->lock);
 	vcpu->arch.vcore = vcore;
 
+	vcpu->arch.cpu_type = KVM_CPU_3S_64;
+	kvmppc_sanity_check(vcpu);
+
 	return vcpu;
 
 free_vcpu:
@@ -800,6 +803,11 @@ int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
 	int r;
 
+	if (!vcpu->arch.sane) {
+		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		return -EINVAL;
+	}
+
 	do {
 		r = kvmppc_run_vcpu(run, vcpu);
 

arch/powerpc/kvm/book3s_pr.c

@@ -153,6 +153,7 @@ void kvmppc_set_pvr(struct kvm_vcpu *vcpu, u32 pvr)
 		if (!to_book3s(vcpu)->hior_sregs)
 			to_book3s(vcpu)->hior = 0xfff00000;
 		to_book3s(vcpu)->msr_mask = 0xffffffffffffffffULL;
+		vcpu->arch.cpu_type = KVM_CPU_3S_64;
 	} else
 #endif
 	{
@@ -160,8 +161,11 @@ void kvmppc_set_pvr(struct kvm_vcpu *vcpu, u32 pvr)
 		if (!to_book3s(vcpu)->hior_sregs)
 			to_book3s(vcpu)->hior = 0;
 		to_book3s(vcpu)->msr_mask = 0xffffffffULL;
+		vcpu->arch.cpu_type = KVM_CPU_3S_32;
 	}
 
+	kvmppc_sanity_check(vcpu);
+
 	/* If we are in hypervisor level on 970, we can tell the CPU to
 	 * treat DCBZ as 32 bytes store */
 	vcpu->arch.hflags &= ~BOOK3S_HFLAG_DCBZ32;
@@ -938,6 +942,12 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 #endif
 	ulong ext_msr;
 
+	/* Check if we can run the vcpu at all */
+	if (!vcpu->arch.sane) {
+		kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		return -EINVAL;
+	}
+
 	/* No need to go into the guest when all we do is going out */
 	if (signal_pending(current)) {
 		kvm_run->exit_reason = KVM_EXIT_INTR;

arch/powerpc/kvm/booke.c

@@ -316,6 +316,11 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 {
 	int ret;
 
+	if (!vcpu->arch.sane) {
+		kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		return -EINVAL;
+	}
+
 	local_irq_disable();
 	kvm_guest_enter();
 	ret = __kvmppc_vcpu_run(kvm_run, vcpu);
@@ -618,6 +623,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 {
 	int i;
+	int r;
 
 	vcpu->arch.pc = 0;
 	vcpu->arch.shared->msr = 0;
@@ -634,7 +640,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 
 	kvmppc_init_timing_stats(vcpu);
 
-	return kvmppc_core_vcpu_setup(vcpu);
+	r = kvmppc_core_vcpu_setup(vcpu);
+	kvmppc_sanity_check(vcpu);
+	return r;
 }
 
 int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)

arch/powerpc/kvm/e500.c

@@ -73,6 +73,8 @@ int kvmppc_core_vcpu_setup(struct kvm_vcpu *vcpu)
 	/* Since booke kvm only support one core, update all vcpus' PIR to 0 */
 	vcpu->vcpu_id = 0;
 
+	vcpu->arch.cpu_type = KVM_CPU_E500V2;
+
 	return 0;
 }
 

arch/powerpc/kvm/powerpc.c

@@ -95,6 +95,31 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
 	return r;
 }
 
+int kvmppc_sanity_check(struct kvm_vcpu *vcpu)
+{
+	int r = false;
+
+	/* We have to know what CPU to virtualize */
+	if (!vcpu->arch.pvr)
+		goto out;
+
+	/* PAPR only works with book3s_64 */
+	if ((vcpu->arch.cpu_type != KVM_CPU_3S_64) && vcpu->arch.papr_enabled)
+		goto out;
+
+#ifdef CONFIG_KVM_BOOK3S_64_HV
+	/* HV KVM can only do PAPR mode for now */
+	if (!vcpu->arch.papr_enabled)
+		goto out;
+#endif
+
+	r = true;
+
+out:
+	vcpu->arch.sane = r;
+	return r ? 0 : -EINVAL;
+}
+
 int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
 	enum emulation_result er;
@@ -582,6 +607,9 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 		break;
 	}
 
+	if (!r)
+		r = kvmppc_sanity_check(vcpu);
+
 	return r;
 }