[PATCH v7 02/23] KVM: Make device name configurable

[Steffen Eiden]

Allow KVM implementations to choose alternative device names. This is
especially useful for architectures providing multiple KVM
implementations simultaneously. Architectures providing multiple KVM
implementations must compile the KVM common code once per
implementation and mange symbols.

Co-developed-by: Nina Schoetterl-Glausch <nsg at linux.ibm.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg at linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden at linux.ibm.com>
---
 include/linux/kvm_host.h |  4 +++-
 virt/kvm/async_pf.c      | 13 +++++++++++--
 virt/kvm/async_pf.h      |  4 ++--
 virt/kvm/kvm_main.c      | 42 ++++++++++++++++++++++++++++++----------
 4 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bfecce1b5955..ec294e419762 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1082,7 +1082,9 @@ 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);
 
 void kvm_get_kvm(struct kvm *kvm);
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index b8aaa96b799b..015761249107 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -19,9 +19,18 @@
 
 static struct kmem_cache *async_pf_cache;
 
-int kvm_async_pf_init(void)
+int kvm_async_pf_init(const char *cache_name)
 {
-	async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
+	char *full_cache_name;
+
+	full_cache_name = kasprintf(GFP_KERNEL, "%s_async_pf", cache_name);
+	if (!full_cache_name)
+		return -ENOMEM;
+
+	async_pf_cache = kmem_cache_create(full_cache_name,
+					   sizeof(struct kvm_async_pf), 0,
+					   SLAB_ACCOUNT, NULL);
+	kfree(full_cache_name);
 
 	if (!async_pf_cache)
 		return -ENOMEM;
diff --git a/virt/kvm/async_pf.h b/virt/kvm/async_pf.h
index 90d1a7d8c6de..4a7b81743248 100644
--- a/virt/kvm/async_pf.h
+++ b/virt/kvm/async_pf.h
@@ -12,11 +12,11 @@
 #define __KVM_ASYNC_PF_H__
 
 #ifdef CONFIG_KVM_ASYNC_PF
-int kvm_async_pf_init(void);
+int kvm_async_pf_init(const char *cache_name);
 void kvm_async_pf_deinit(void);
 void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu);
 #else
-#define kvm_async_pf_init() (0)
+#define kvm_async_pf_init(_name) (0)
 #define kvm_async_pf_deinit() do {} while (0)
 #define kvm_async_pf_vcpu_init(C) do {} while (0)
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 34b4c43908b3..823b693d89e6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5595,9 +5595,7 @@ 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
@@ -6369,13 +6367,13 @@ 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];
@@ -6511,23 +6509,42 @@ 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)
+{
+	char *cache_name;
 	int r;
 	int cpu;
 
+	kvm_dev.minor = minor;
+	kvm_dev.name = kstrdup_const(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);
+
+	r = -ENOMEM;
+	cache_name = kasprintf(GFP_KERNEL, "%s_vcpu", dev_name);
+	if (!cache_name)
+		goto err_dev_name;
 	kvm_vcpu_cache =
-		kmem_cache_create_usercopy("kvm_vcpu", vcpu_size, vcpu_align,
+		kmem_cache_create_usercopy(cache_name, vcpu_size, vcpu_align,
 					   SLAB_ACCOUNT,
 					   offsetof(struct kvm_vcpu, arch),
 					   offsetofend(struct kvm_vcpu, stats_id)
 					   - offsetof(struct kvm_vcpu, arch),
 					   NULL);
+	kfree(cache_name);
+
 	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),
@@ -6541,7 +6558,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 	if (r)
 		goto err_irqfd;
 
-	r = kvm_async_pf_init();
+	r = kvm_async_pf_init(dev_name);
 	if (r)
 		goto err_async_pf;
 
@@ -6553,7 +6570,7 @@ 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))
@@ -6595,6 +6612,8 @@ 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_const(kvm_dev.name);
 	return r;
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init);
@@ -6620,5 +6639,8 @@ void kvm_exit(void)
 	kvm_vfio_ops_exit();
 	kvm_async_pf_deinit();
 	kvm_irqfd_exit();
+
+	kfree_const(kvm_dev.name);
+	kvm_dev.name = NULL;
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_exit);
-- 
2.53.0