1 files changed, 35 insertions, 19 deletions

diff --git a/arch/powerpc/kvm/book3s_rtas.c b/arch/powerpc/kvm/book3s_rtas.c
index 2d3b2b1cc272..6808bda0dbc1 100644
--- a/arch/powerpc/kvm/book3s_rtas.c
+++ b/arch/powerpc/kvm/book3s_rtas.c
@@ -1,9 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright 2012 Michael Ellerman, IBM Corporation.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2, as
- * published by the Free Software Foundation.
  */
 
 #include <linux/kernel.h>
@@ -33,7 +30,7 @@ static void kvm_rtas_set_xive(struct kvm_vcpu *vcpu, struct rtas_args *args)
 	server = be32_to_cpu(args->args[1]);
 	priority = be32_to_cpu(args->args[2]);
 
-	if (xive_enabled())
+	if (xics_on_xive())
 		rc = kvmppc_xive_set_xive(vcpu->kvm, irq, server, priority);
 	else
 		rc = kvmppc_xics_set_xive(vcpu->kvm, irq, server, priority);
@@ -56,7 +53,7 @@ static void kvm_rtas_get_xive(struct kvm_vcpu *vcpu, struct rtas_args *args)
 	irq = be32_to_cpu(args->args[0]);
 
 	server = priority = 0;
-	if (xive_enabled())
+	if (xics_on_xive())
 		rc = kvmppc_xive_get_xive(vcpu->kvm, irq, &server, &priority);
 	else
 		rc = kvmppc_xics_get_xive(vcpu->kvm, irq, &server, &priority);
@@ -83,7 +80,7 @@ static void kvm_rtas_int_off(struct kvm_vcpu *vcpu, struct rtas_args *args)
 
 	irq = be32_to_cpu(args->args[0]);
 
-	if (xive_enabled())
+	if (xics_on_xive())
 		rc = kvmppc_xive_int_off(vcpu->kvm, irq);
 	else
 		rc = kvmppc_xics_int_off(vcpu->kvm, irq);
@@ -105,7 +102,7 @@ static void kvm_rtas_int_on(struct kvm_vcpu *vcpu, struct rtas_args *args)
 
 	irq = be32_to_cpu(args->args[0]);
 
-	if (xive_enabled())
+	if (xics_on_xive())
 		rc = kvmppc_xive_int_on(vcpu->kvm, irq);
 	else
 		rc = kvmppc_xics_int_on(vcpu->kvm, irq);
@@ -146,7 +143,7 @@ static int rtas_token_undefine(struct kvm *kvm, char *name)
 {
 	struct rtas_token_definition *d, *tmp;
 
-	lockdep_assert_held(&kvm->lock);
+	lockdep_assert_held(&kvm->arch.rtas_token_lock);
 
 	list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) {
 		if (rtas_name_matches(d->handler->name, name)) {
@@ -167,7 +164,7 @@ static int rtas_token_define(struct kvm *kvm, char *name, u64 token)
 	bool found;
 	int i;
 
-	lockdep_assert_held(&kvm->lock);
+	lockdep_assert_held(&kvm->arch.rtas_token_lock);
 
 	list_for_each_entry(d, &kvm->arch.rtas_tokens, list) {
 		if (d->token == token)
@@ -206,14 +203,14 @@ int kvm_vm_ioctl_rtas_define_token(struct kvm *kvm, void __user *argp)
 	if (copy_from_user(&args, argp, sizeof(args)))
 		return -EFAULT;
 
-	mutex_lock(&kvm->lock);
+	mutex_lock(&kvm->arch.rtas_token_lock);
 
 	if (args.token)
 		rc = rtas_token_define(kvm, args.name, args.token);
 	else
 		rc = rtas_token_undefine(kvm, args.name);
 
-	mutex_unlock(&kvm->lock);
+	mutex_unlock(&kvm->arch.rtas_token_lock);
 
 	return rc;
 }
@@ -232,7 +229,9 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu)
 	 */
 	args_phys = kvmppc_get_gpr(vcpu, 4) & KVM_PAM;
 
+	kvm_vcpu_srcu_read_lock(vcpu);
 	rc = kvm_read_guest(vcpu->kvm, args_phys, &args, sizeof(args));
+	kvm_vcpu_srcu_read_unlock(vcpu);
 	if (rc)
 		goto fail;
 
@@ -243,9 +242,20 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu)
 	 * value so we can restore it on the way out.
 	 */
 	orig_rets = args.rets;
+	if (be32_to_cpu(args.nargs) >= ARRAY_SIZE(args.args)) {
+		/*
+		 * Don't overflow our args array: ensure there is room for
+		 * at least rets[0] (even if the call specifies 0 nret).
+		 *
+		 * Each handler must then check for the correct nargs and nret
+		 * values, but they may always return failure in rets[0].
+		 */
+		rc = -EINVAL;
+		goto fail;
+	}
 	args.rets = &args.args[be32_to_cpu(args.nargs)];
 
-	mutex_lock(&vcpu->kvm->lock);
+	mutex_lock(&vcpu->kvm->arch.rtas_token_lock);
 
 	rc = -ENOENT;
 	list_for_each_entry(d, &vcpu->kvm->arch.rtas_tokens, list) {
@@ -256,7 +266,7 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu)
 		}
 	}
 
-	mutex_unlock(&vcpu->kvm->lock);
+	mutex_unlock(&vcpu->kvm->arch.rtas_token_lock);
 
 	if (rc == 0) {
 		args.rets = orig_rets;
@@ -270,9 +280,17 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu)
 fail:
 	/*
 	 * We only get here if the guest has called RTAS with a bogus
-	 * args pointer. That means we can't get to the args, and so we
-	 * can't fail the RTAS call. So fail right out to userspace,
-	 * which should kill the guest.
+	 * args pointer or nargs/nret values that would overflow the
+	 * array. That means we can't get to the args, and so we can't
+	 * fail the RTAS call. So fail right out to userspace, which
+	 * should kill the guest.
+	 *
+	 * SLOF should actually pass the hcall return value from the
+	 * rtas handler call in r3, so enter_rtas could be modified to
+	 * return a failure indication in r3 and we could return such
+	 * errors to the guest rather than failing to host userspace.
+	 * However old guests that don't test for failure could then
+	 * continue silently after errors, so for now we won't do this.
 	 */
 	return rc;
 }
@@ -282,8 +300,6 @@ void kvmppc_rtas_tokens_free(struct kvm *kvm)
 {
 	struct rtas_token_definition *d, *tmp;
 
-	lockdep_assert_held(&kvm->lock);
-
 	list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) {
 		list_del(&d->list);
 		kfree(d);