[PATCH v4 04/27] KVM: Make device name configurable

[Steffen Eiden <seiden@linux.ibm.com>]

Allow KVM implementations to choose alternative device names. This is
especially useful for architectures providing multiple KVM
implementations simultaneously.

Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 include/linux/kvm_host.h |  4 +++-
 virt/kvm/kvm_main.c      | 31 +++++++++++++++++++++++--------
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1f967b1d68b9..aa573e2530f7 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1069,7 +1069,9 @@ static inline void kvm_irqfd_exit(void)
 {
 }
 #endif
-int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module);
+int kvm_init(unsigned int vcpu_size, unsigned int vcpu_align, struct module *module);
+int kvm_init_with_dev(unsigned int vcpu_size, unsigned int vcpu_align,
+		      struct module *module, const char *dev_name, int minor);
 void kvm_exit(void);
 
 bool file_is_kvm(struct file *file);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 271884089f58..dcad33cc2f25 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5542,9 +5542,7 @@ static struct file_operations kvm_chardev_ops = {
 };
 
 static struct miscdevice kvm_dev = {
-	KVM_MINOR,
-	"kvm",
-	&kvm_chardev_ops,
+	.fops = &kvm_chardev_ops,
 };
 
 #ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
@@ -6322,13 +6320,13 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
 	kfree(env);
 }
 
-static void kvm_init_debug(void)
+static void kvm_init_debug(const char *dev_name)
 {
 	const struct file_operations *fops;
 	const struct kvm_stats_desc *pdesc;
 	int i;
 
-	kvm_debugfs_dir = debugfs_create_dir("kvm", NULL);
+	kvm_debugfs_dir = debugfs_create_dir(dev_name, NULL);
 
 	for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) {
 		pdesc = &kvm_vm_stats_desc[i];
@@ -6464,11 +6462,22 @@ void kvm_unregister_perf_callbacks(void)
 }
 #endif
 
-int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
+int kvm_init(unsigned int vcpu_size, unsigned int vcpu_align, struct module *module)
+{
+	return kvm_init_with_dev(vcpu_size, vcpu_align, module, "kvm", KVM_MINOR);
+}
+
+int kvm_init_with_dev(unsigned int vcpu_size, unsigned int vcpu_align,
+		      struct module *module, const char *dev_name, int minor)
 {
 	int r;
 	int cpu;
 
+	kvm_dev.minor = minor;
+	kvm_dev.name = kstrdup(dev_name, GFP_KERNEL);
+	if (!kvm_dev.name)
+		return -ENOMEM;
+
 	/* A kmem cache lets us meet the alignment requirements of fx_save. */
 	if (!vcpu_align)
 		vcpu_align = __alignof__(struct kvm_vcpu);
@@ -6479,8 +6488,9 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 					   offsetofend(struct kvm_vcpu, stats_id)
 					   - offsetof(struct kvm_vcpu, arch),
 					   NULL);
+	r = -ENOMEM;
 	if (!kvm_vcpu_cache)
-		return -ENOMEM;
+		goto err_dev_name;
 
 	for_each_possible_cpu(cpu) {
 		if (!alloc_cpumask_var_node(&per_cpu(cpu_kick_mask, cpu),
@@ -6506,7 +6516,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 	kvm_preempt_ops.sched_in = kvm_sched_in;
 	kvm_preempt_ops.sched_out = kvm_sched_out;
 
-	kvm_init_debug();
+	kvm_init_debug(kvm_dev.name);
 
 	r = kvm_vfio_ops_init();
 	if (WARN_ON_ONCE(r))
@@ -6547,6 +6557,8 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 	for_each_possible_cpu(cpu)
 		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
 	kmem_cache_destroy(kvm_vcpu_cache);
+err_dev_name:
+	kfree(kvm_dev.name);
 	return r;
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init);
@@ -6572,5 +6584,8 @@ void kvm_exit(void)
 	kvm_vfio_ops_exit();
 	kvm_async_pf_deinit();
 	kvm_irqfd_exit();
+
+	kfree(kvm_dev.name);
+	kvm_dev.name = NULL;
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_exit);
-- 
2.53.0