[PATCH RFC v7 4/8] KVM: Add kvm_gmem_exit() cleanup function

[Shivank Garg <shivankg@amd.com>]

Add empty kvm_gmem_exit() function for proper cleanup of guest memory
resources. Call it from both kvm_init() error path and kvm_exit().

This is preparatory change for upcoming work that involves KVM guest_memfd
using inodes to store metadata for backing memory.

Signed-off-by: Shivank Garg <shivankg@amd.com>
---
 virt/kvm/guest_memfd.c | 5 +++++
 virt/kvm/kvm_main.c    | 2 ++
 virt/kvm/kvm_mm.h      | 6 ++++++
 3 files changed, 13 insertions(+)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index b2aa6bf24d3a..88453b040926 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -323,6 +323,11 @@ void kvm_gmem_init(struct module *module)
 	kvm_gmem_fops.owner = module;
 }
 
+void kvm_gmem_exit(void)
+{
+
+}
+
 static int kvm_gmem_migrate_folio(struct address_space *mapping,
 				  struct folio *dst, struct folio *src,
 				  enum migrate_mode mode)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e85b33a92624..39580f79908a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -6441,6 +6441,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 err_register:
 	kvm_uninit_virtualization();
 err_virt:
+	kvm_gmem_exit();
 	kvm_vfio_ops_exit();
 err_vfio:
 	kvm_async_pf_deinit();
@@ -6471,6 +6472,7 @@ void kvm_exit(void)
 	debugfs_remove_recursive(kvm_debugfs_dir);
 	for_each_possible_cpu(cpu)
 		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
+	kvm_gmem_exit();
 	kmem_cache_destroy(kvm_vcpu_cache);
 	kvm_vfio_ops_exit();
 	kvm_async_pf_deinit();
diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h
index acef3f5c582a..8070956b1a43 100644
--- a/virt/kvm/kvm_mm.h
+++ b/virt/kvm/kvm_mm.h
@@ -69,6 +69,7 @@ static inline void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
 
 #ifdef CONFIG_KVM_PRIVATE_MEM
 void kvm_gmem_init(struct module *module);
+void kvm_gmem_exit(void);
 int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args);
 int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
 		  unsigned int fd, loff_t offset);
@@ -79,6 +80,11 @@ static inline void kvm_gmem_init(struct module *module)
 
 }
 
+static inline void kvm_gmem_exit(void)
+{
+
+}
+
 static inline int kvm_gmem_bind(struct kvm *kvm,
 					 struct kvm_memory_slot *slot,
 					 unsigned int fd, loff_t offset)
-- 
2.34.1