[PATCH v12 01/12] KVM: guest_memfd: Rename "struct kvm_gmem" to "struct gmem_file"

Sean Christopherson
2025-10-07T22:14:39Z

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.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
virt/kvm/guest_memfd.c | 100 ++++++++++++++++++++++-------------------
1 file changed, 54 insertions(+), 46 deletions(-)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index fbca8c0972da..3c57fb42f12c 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;
@@ -110,16 +119,16 @@ 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 = {
@@ -152,20 +161,20 @@ 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);
@@ -176,10 +185,10 @@ 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)
@@ -277,9 +286,9 @@ 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;

/*
@@ -299,7 +308,7 @@ 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);

/*
@@ -307,18 +316,18 @@ 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);

@@ -493,7 +502,7 @@ 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;
@@ -502,14 +511,13 @@ 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;
@@ -531,15 +539,15 @@ 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;
@@ -564,7 +572,7 @@ 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;
@@ -578,8 +586,8 @@ 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);
@@ -593,8 +601,8 @@ 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;
}
@@ -609,7 +617,7 @@ 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);

/*
@@ -627,7 +635,7 @@ 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;

/*
@@ -638,10 +646,10 @@ 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()
@@ -659,18 +667,18 @@ 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);
}

- gmem = file->private_data;
- if (xa_load(&gmem->bindings, index) != slot) {
- WARN_ON_ONCE(xa_load(&gmem->bindings, index));
+ f = file->private_data;
+ if (xa_load(&f->bindings, index) != slot) {
+ WARN_ON_ONCE(xa_load(&f->bindings, index));
return ERR_PTR(-EIO);
}

--
2.51.0.710.ga91ca5db03-goog