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KVM: guest_memfd: Add gmem_inode.flags field instead of using i_private

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Track a guest_memfd instance's flags in gmem_inode instead of burying them
in i_private.  Burning an extra 8 bytes per inode is well worth the added
clarity provided by explicit tracking.

Reviewed-by: Shivank Garg <shivankg@amd.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lore.kernel.org/r/20251016172853.52451-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2025-10-16 10:28:53 -07:00
parent 38ccc50ac0
commit e66438bb81
1 changed files with 9 additions and 6 deletions
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15
virt/kvm/guest_memfd.c
View File

@@ -30,6 +30,8 @@ struct gmem_file {
struct gmem_inode {
struct shared_policy policy;
struct inode vfs_inode;
u64 flags;
};
static __always_inline struct gmem_inode *GMEM_I(struct inode *inode)
@@ -154,7 +156,7 @@ static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index)
static enum kvm_gfn_range_filter kvm_gmem_get_invalidate_filter(struct inode *inode)
{
if ((u64)inode->i_private & GUEST_MEMFD_FLAG_INIT_SHARED)
if (GMEM_I(inode)->flags & GUEST_MEMFD_FLAG_INIT_SHARED)
return KVM_FILTER_SHARED;
return KVM_FILTER_PRIVATE;
@@ -385,9 +387,7 @@ static inline struct file *kvm_gmem_get_file(struct kvm_memory_slot *slot)
static bool kvm_gmem_supports_mmap(struct inode *inode)
{
const u64 flags = (u64)inode->i_private;
return flags & GUEST_MEMFD_FLAG_MMAP;
return GMEM_I(inode)->flags & GUEST_MEMFD_FLAG_MMAP;
}
static vm_fault_t kvm_gmem_fault_user_mapping(struct vm_fault *vmf)
@@ -399,7 +399,7 @@ static vm_fault_t kvm_gmem_fault_user_mapping(struct vm_fault *vmf)
if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode))
return VM_FAULT_SIGBUS;
if (!((u64)inode->i_private & GUEST_MEMFD_FLAG_INIT_SHARED))
if (!(GMEM_I(inode)->flags & GUEST_MEMFD_FLAG_INIT_SHARED))
return VM_FAULT_SIGBUS;
folio = kvm_gmem_get_folio(inode, vmf->pgoff);
@@ -588,7 +588,6 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
goto err_fops;
}
inode->i_private = (void *)(unsigned long)flags;
inode->i_op = &kvm_gmem_iops;
inode->i_mapping->a_ops = &kvm_gmem_aops;
inode->i_mode |= S_IFREG;
@@ -598,6 +597,8 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
/* Unmovable mappings are supposed to be marked unevictable as well. */
WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping));
GMEM_I(inode)->flags = flags;
file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR, &kvm_gmem_fops);
if (IS_ERR(file)) {
err = PTR_ERR(file);
@@ -917,6 +918,8 @@ static struct inode *kvm_gmem_alloc_inode(struct super_block *sb)
return NULL;
mpol_shared_policy_init(&gi->policy, NULL);
gi->flags = 0;
return &gi->vfs_inode;
}