[PATCH v13 01/12] KVM: guest_memfd: Rename "struct kvm_gmem" to "struct gmem_file"

[Sean Christopherson <seanjc@google.com>]

Rename the "kvm_gmem" structure to "gmem_file" in anticipation of using
dedicated guest_memfd inodes instead of anonyomous inodes, at which point
the "kvm_gmem" nomenclature becomes quite misleading.  In guest_memfd,
inodes are effectively the raw underlying physical storage, and will be
used to track properties of the physical memory, while each gmem file is
effectively a single VM's view of that storage, and is used to track assets
specific to its associated VM, e.g. memslots=>gmem bindings.

Using "kvm_gmem" suggests that the per-VM/per-file structures are _the_
guest_memfd instance, which almost the exact opposite of reality.

Opportunistically rename local variables from "gmem" to "f", again to
avoid confusion once guest_memfd specific inodes come along.

No functional change intended.

Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Tested-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 virt/kvm/guest_memfd.c | 98 +++++++++++++++++++++++-------------------
 1 file changed, 53 insertions(+), 45 deletions(-)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 1e4af29159ea..2989c5fe426f 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -7,7 +7,16 @@
 
 #include "kvm_mm.h"
 
-struct kvm_gmem {
+/*
+ * A guest_memfd instance can be associated multiple VMs, each with its own
+ * "view" of the underlying physical memory.
+ *
+ * The gmem's inode is effectively the raw underlying physical storage, and is
+ * used to track properties of the physical memory, while each gmem file is
+ * effectively a single VM's view of that storage, and is used to track assets
+ * specific to its associated VM, e.g. memslots=>gmem bindings.
+ */
+struct gmem_file {
 	struct kvm *kvm;
 	struct xarray bindings;
 	struct list_head entry;
@@ -115,16 +124,16 @@ static enum kvm_gfn_range_filter kvm_gmem_get_invalidate_filter(struct inode *in
 	return KVM_FILTER_PRIVATE;
 }
 
-static void __kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start,
+static void __kvm_gmem_invalidate_begin(struct gmem_file *f, pgoff_t start,
 					pgoff_t end,
 					enum kvm_gfn_range_filter attr_filter)
 {
 	bool flush = false, found_memslot = false;
 	struct kvm_memory_slot *slot;
-	struct kvm *kvm = gmem->kvm;
+	struct kvm *kvm = f->kvm;
 	unsigned long index;
 
-	xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) {
+	xa_for_each_range(&f->bindings, index, slot, start, end - 1) {
 		pgoff_t pgoff = slot->gmem.pgoff;
 
 		struct kvm_gfn_range gfn_range = {
@@ -157,20 +166,20 @@ static void kvm_gmem_invalidate_begin(struct inode *inode, pgoff_t start,
 {
 	struct list_head *gmem_list = &inode->i_mapping->i_private_list;
 	enum kvm_gfn_range_filter attr_filter;
-	struct kvm_gmem *gmem;
+	struct gmem_file *f;
 
 	attr_filter = kvm_gmem_get_invalidate_filter(inode);
 
-	list_for_each_entry(gmem, gmem_list, entry)
-		__kvm_gmem_invalidate_begin(gmem, start, end, attr_filter);
+	list_for_each_entry(f, gmem_list, entry)
+		__kvm_gmem_invalidate_begin(f, start, end, attr_filter);
 }
 
-static void __kvm_gmem_invalidate_end(struct kvm_gmem *gmem, pgoff_t start,
+static void __kvm_gmem_invalidate_end(struct gmem_file *f, pgoff_t start,
 				      pgoff_t end)
 {
-	struct kvm *kvm = gmem->kvm;
+	struct kvm *kvm = f->kvm;
 
-	if (xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) {
+	if (xa_find(&f->bindings, &start, end - 1, XA_PRESENT)) {
 		KVM_MMU_LOCK(kvm);
 		kvm_mmu_invalidate_end(kvm);
 		KVM_MMU_UNLOCK(kvm);
@@ -181,10 +190,10 @@ static void kvm_gmem_invalidate_end(struct inode *inode, pgoff_t start,
 				    pgoff_t end)
 {
 	struct list_head *gmem_list = &inode->i_mapping->i_private_list;
-	struct kvm_gmem *gmem;
+	struct gmem_file *f;
 
-	list_for_each_entry(gmem, gmem_list, entry)
-		__kvm_gmem_invalidate_end(gmem, start, end);
+	list_for_each_entry(f, gmem_list, entry)
+		__kvm_gmem_invalidate_end(f, start, end);
 }
 
 static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
@@ -282,9 +291,9 @@ static long kvm_gmem_fallocate(struct file *file, int mode, loff_t offset,
 
 static int kvm_gmem_release(struct inode *inode, struct file *file)
 {
-	struct kvm_gmem *gmem = file->private_data;
+	struct gmem_file *f = file->private_data;
 	struct kvm_memory_slot *slot;
-	struct kvm *kvm = gmem->kvm;
+	struct kvm *kvm = f->kvm;
 	unsigned long index;
 
 	/*
@@ -304,7 +313,7 @@ static int kvm_gmem_release(struct inode *inode, struct file *file)
 
 	filemap_invalidate_lock(inode->i_mapping);
 
-	xa_for_each(&gmem->bindings, index, slot)
+	xa_for_each(&f->bindings, index, slot)
 		WRITE_ONCE(slot->gmem.file, NULL);
 
 	/*
@@ -312,18 +321,18 @@ static int kvm_gmem_release(struct inode *inode, struct file *file)
 	 * Zap all SPTEs pointed at by this file.  Do not free the backing
 	 * memory, as its lifetime is associated with the inode, not the file.
 	 */
-	__kvm_gmem_invalidate_begin(gmem, 0, -1ul,
+	__kvm_gmem_invalidate_begin(f, 0, -1ul,
 				    kvm_gmem_get_invalidate_filter(inode));
-	__kvm_gmem_invalidate_end(gmem, 0, -1ul);
+	__kvm_gmem_invalidate_end(f, 0, -1ul);
 
-	list_del(&gmem->entry);
+	list_del(&f->entry);
 
 	filemap_invalidate_unlock(inode->i_mapping);
 
 	mutex_unlock(&kvm->slots_lock);
 
-	xa_destroy(&gmem->bindings);
-	kfree(gmem);
+	xa_destroy(&f->bindings);
+	kfree(f);
 
 	kvm_put_kvm(kvm);
 
@@ -491,7 +500,7 @@ bool __weak kvm_arch_supports_gmem_init_shared(struct kvm *kvm)
 static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
 {
 	const char *anon_name = "[kvm-gmem]";
-	struct kvm_gmem *gmem;
+	struct gmem_file *f;
 	struct inode *inode;
 	struct file *file;
 	int fd, err;
@@ -500,14 +509,13 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
 	if (fd < 0)
 		return fd;
 
-	gmem = kzalloc(sizeof(*gmem), GFP_KERNEL);
-	if (!gmem) {
+	f = kzalloc(sizeof(*f), GFP_KERNEL);
+	if (!f) {
 		err = -ENOMEM;
 		goto err_fd;
 	}
 
-	file = anon_inode_create_getfile(anon_name, &kvm_gmem_fops, gmem,
-					 O_RDWR, NULL);
+	file = anon_inode_create_getfile(anon_name, &kvm_gmem_fops, f, O_RDWR, NULL);
 	if (IS_ERR(file)) {
 		err = PTR_ERR(file);
 		goto err_gmem;
@@ -529,15 +537,15 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
 	WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping));
 
 	kvm_get_kvm(kvm);
-	gmem->kvm = kvm;
-	xa_init(&gmem->bindings);
-	list_add(&gmem->entry, &inode->i_mapping->i_private_list);
+	f->kvm = kvm;
+	xa_init(&f->bindings);
+	list_add(&f->entry, &inode->i_mapping->i_private_list);
 
 	fd_install(fd, file);
 	return fd;
 
 err_gmem:
-	kfree(gmem);
+	kfree(f);
 err_fd:
 	put_unused_fd(fd);
 	return err;
@@ -562,7 +570,7 @@ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
 {
 	loff_t size = slot->npages << PAGE_SHIFT;
 	unsigned long start, end;
-	struct kvm_gmem *gmem;
+	struct gmem_file *f;
 	struct inode *inode;
 	struct file *file;
 	int r = -EINVAL;
@@ -576,8 +584,8 @@ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
 	if (file->f_op != &kvm_gmem_fops)
 		goto err;
 
-	gmem = file->private_data;
-	if (gmem->kvm != kvm)
+	f = file->private_data;
+	if (f->kvm != kvm)
 		goto err;
 
 	inode = file_inode(file);
@@ -591,8 +599,8 @@ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
 	start = offset >> PAGE_SHIFT;
 	end = start + slot->npages;
 
-	if (!xa_empty(&gmem->bindings) &&
-	    xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) {
+	if (!xa_empty(&f->bindings) &&
+	    xa_find(&f->bindings, &start, end - 1, XA_PRESENT)) {
 		filemap_invalidate_unlock(inode->i_mapping);
 		goto err;
 	}
@@ -607,7 +615,7 @@ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
 	if (kvm_gmem_supports_mmap(inode))
 		slot->flags |= KVM_MEMSLOT_GMEM_ONLY;
 
-	xa_store_range(&gmem->bindings, start, end - 1, slot, GFP_KERNEL);
+	xa_store_range(&f->bindings, start, end - 1, slot, GFP_KERNEL);
 	filemap_invalidate_unlock(inode->i_mapping);
 
 	/*
@@ -625,7 +633,7 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
 {
 	unsigned long start = slot->gmem.pgoff;
 	unsigned long end = start + slot->npages;
-	struct kvm_gmem *gmem;
+	struct gmem_file *f;
 	struct file *file;
 
 	/*
@@ -636,10 +644,10 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
 	if (!file)
 		return;
 
-	gmem = file->private_data;
+	f = file->private_data;
 
 	filemap_invalidate_lock(file->f_mapping);
-	xa_store_range(&gmem->bindings, start, end - 1, NULL, GFP_KERNEL);
+	xa_store_range(&f->bindings, start, end - 1, NULL, GFP_KERNEL);
 
 	/*
 	 * synchronize_srcu(&kvm->srcu) ensured that kvm_gmem_get_pfn()
@@ -657,17 +665,17 @@ static struct folio *__kvm_gmem_get_pfn(struct file *file,
 					pgoff_t index, kvm_pfn_t *pfn,
 					bool *is_prepared, int *max_order)
 {
-	struct file *gmem_file = READ_ONCE(slot->gmem.file);
-	struct kvm_gmem *gmem = file->private_data;
+	struct file *slot_file = READ_ONCE(slot->gmem.file);
+	struct gmem_file *f = file->private_data;
 	struct folio *folio;
 
-	if (file != gmem_file) {
-		WARN_ON_ONCE(gmem_file);
+	if (file != slot_file) {
+		WARN_ON_ONCE(slot_file);
 		return ERR_PTR(-EFAULT);
 	}
 
-	if (xa_load(&gmem->bindings, index) != slot) {
-		WARN_ON_ONCE(xa_load(&gmem->bindings, index));
+	if (xa_load(&f->bindings, index) != slot) {
+		WARN_ON_ONCE(xa_load(&f->bindings, index));
 		return ERR_PTR(-EIO);
 	}
 
-- 
2.51.0.858.gf9c4a03a3a-goog