KVM: PPC: Book3S: Allow only implemented hcalls to be enabled or disabled

This adds code to check that when the KVM_CAP_PPC_ENABLE_HCALL
capability is used to enable or disable in-kernel handling of an
hcall, that the hcall is actually implemented by the kernel.
If not an EINVAL error is returned.

This also checks the default-enabled list of hcalls and prints a
warning if any hcall there is not actually implemented.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

Documentation/virtual/kvm/api.txt

@@ -3039,3 +3039,7 @@ not to attempt to handle the hcall, but will always exit to userspace
 to handle it.  Note that it may not make sense to enable some and
 disable others of a group of related hcalls, but KVM does not prevent
 userspace from doing that.
+
+If the hcall number specified is not one that has an in-kernel
+implementation, the KVM_ENABLE_CAP ioctl will fail with an EINVAL
+error.

arch/powerpc/include/asm/kvm_book3s.h

@@ -146,6 +146,7 @@ extern void kvmppc_mmu_invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *
 extern int kvmppc_mmu_hpte_sysinit(void);
 extern void kvmppc_mmu_hpte_sysexit(void);
 extern int kvmppc_mmu_hv_init(void);
+extern int kvmppc_book3s_hcall_implemented(struct kvm *kvm, unsigned long hc);
 
 extern int kvmppc_ld(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr, bool data);
 extern int kvmppc_st(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr, bool data);
@@ -188,6 +189,8 @@ extern u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst);
 extern ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst);
 extern int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd);
 extern void kvmppc_pr_init_default_hcalls(struct kvm *kvm);
+extern int kvmppc_hcall_impl_pr(unsigned long cmd);
+extern int kvmppc_hcall_impl_hv_realmode(unsigned long cmd);
 extern void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu,
 				 struct kvm_vcpu *vcpu);
 extern void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu,

arch/powerpc/include/asm/kvm_ppc.h

@@ -228,7 +228,7 @@ struct kvmppc_ops {
 	void (*fast_vcpu_kick)(struct kvm_vcpu *vcpu);
 	long (*arch_vm_ioctl)(struct file *filp, unsigned int ioctl,
 			      unsigned long arg);
-
+	int (*hcall_implemented)(unsigned long hcall);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;

arch/powerpc/kvm/book3s.c

@@ -925,6 +925,11 @@ int kvmppc_core_check_processor_compat(void)
 	return 0;
 }
 
+int kvmppc_book3s_hcall_implemented(struct kvm *kvm, unsigned long hcall)
+{
+	return kvm->arch.kvm_ops->hcall_implemented(hcall);
+}
+
 static int kvmppc_book3s_init(void)
 {
 	int r;

arch/powerpc/kvm/book3s_hv.c

@@ -645,6 +645,28 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
 	return RESUME_GUEST;
 }
 
+static int kvmppc_hcall_impl_hv(unsigned long cmd)
+{
+	switch (cmd) {
+	case H_CEDE:
+	case H_PROD:
+	case H_CONFER:
+	case H_REGISTER_VPA:
+#ifdef CONFIG_KVM_XICS
+	case H_XIRR:
+	case H_CPPR:
+	case H_EOI:
+	case H_IPI:
+	case H_IPOLL:
+	case H_XIRR_X:
+#endif
+		return 1;
+	}
+
+	/* See if it's in the real-mode table */
+	return kvmppc_hcall_impl_hv_realmode(cmd);
+}
+
 static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
 				 struct task_struct *tsk)
 {
@@ -2451,9 +2473,13 @@ static unsigned int default_hcall_list[] = {
 static void init_default_hcalls(void)
 {
 	int i;
+	unsigned int hcall;
 
-	for (i = 0; default_hcall_list[i]; ++i)
+	for (i = 0; default_hcall_list[i]; ++i) {
-		__set_bit(default_hcall_list[i] / 4, default_enabled_hcalls);
+		hcall = default_hcall_list[i];
+		WARN_ON(!kvmppc_hcall_impl_hv(hcall));
+		__set_bit(hcall / 4, default_enabled_hcalls);
+	}
 }
 
 static struct kvmppc_ops kvm_ops_hv = {
@@ -2488,6 +2514,7 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.emulate_mfspr = kvmppc_core_emulate_mfspr_hv,
 	.fast_vcpu_kick = kvmppc_fast_vcpu_kick_hv,
 	.arch_vm_ioctl  = kvm_arch_vm_ioctl_hv,
+	.hcall_implemented = kvmppc_hcall_impl_hv,
 };
 
 static int kvmppc_book3s_init_hv(void)

arch/powerpc/kvm/book3s_hv_builtin.c

@@ -212,3 +212,16 @@ bool kvm_hv_mode_active(void)
 {
 	return atomic_read(&hv_vm_count) != 0;
 }
+
+extern int hcall_real_table[], hcall_real_table_end[];
+
+int kvmppc_hcall_impl_hv_realmode(unsigned long cmd)
+{
+	cmd /= 4;
+	if (cmd < hcall_real_table_end - hcall_real_table &&
+	    hcall_real_table[cmd])
+		return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -2042,6 +2042,7 @@ hcall_real_table:
 	.long	0		/* 0x12c */
 	.long	0		/* 0x130 */
 	.long	DOTSYM(kvmppc_h_set_xdabr) - hcall_real_table
+	.globl	hcall_real_table_end
 hcall_real_table_end:
 
 ignore_hdec:

arch/powerpc/kvm/book3s_pr.c

@@ -1670,6 +1670,9 @@ static struct kvmppc_ops kvm_ops_pr = {
 	.emulate_mfspr = kvmppc_core_emulate_mfspr_pr,
 	.fast_vcpu_kick = kvm_vcpu_kick,
 	.arch_vm_ioctl  = kvm_arch_vm_ioctl_pr,
+#ifdef CONFIG_PPC_BOOK3S_64
+	.hcall_implemented = kvmppc_hcall_impl_pr,
+#endif
 };
 
 

arch/powerpc/kvm/book3s_pr_papr.c

@@ -309,6 +309,27 @@ int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
 	return EMULATE_FAIL;
 }
 
+int kvmppc_hcall_impl_pr(unsigned long cmd)
+{
+	switch (cmd) {
+	case H_ENTER:
+	case H_REMOVE:
+	case H_PROTECT:
+	case H_BULK_REMOVE:
+	case H_PUT_TCE:
+	case H_CEDE:
+#ifdef CONFIG_KVM_XICS
+	case H_XIRR:
+	case H_CPPR:
+	case H_EOI:
+	case H_IPI:
+	case H_IPOLL:
+	case H_XIRR_X:
+#endif
+		return 1;
+	}
+	return 0;
+}
 
 /*
  * List of hcall numbers to enable by default.
@@ -337,7 +358,11 @@ static unsigned int default_hcall_list[] = {
 void kvmppc_pr_init_default_hcalls(struct kvm *kvm)
 {
 	int i;
+	unsigned int hcall;
 
-	for (i = 0; default_hcall_list[i]; ++i)
+	for (i = 0; default_hcall_list[i]; ++i) {
-		__set_bit(default_hcall_list[i] / 4, kvm->arch.enabled_hcalls);
+		hcall = default_hcall_list[i];
+		WARN_ON(!kvmppc_hcall_impl_pr(hcall));
+		__set_bit(hcall / 4, kvm->arch.enabled_hcalls);
+	}
 }

arch/powerpc/kvm/powerpc.c

@@ -1119,6 +1119,8 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 		if (hcall > MAX_HCALL_OPCODE || (hcall & 3) ||
 		    cap->args[1] > 1)
 			break;
+		if (!kvmppc_book3s_hcall_implemented(kvm, hcall))
+			break;
 		if (cap->args[1])
 			set_bit(hcall / 4, kvm->arch.enabled_hcalls);
 		else