Commit e66438bb authored by Sean Christopherson's avatar Sean Christopherson
Browse files

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



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: default avatarShivank Garg <shivankg@amd.com>
Tested-by: default avatarShivank Garg <shivankg@amd.com>
Link: https://lore.kernel.org/r/20251016172853.52451-13-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 38ccc50a

virt/kvm/guest_memfd.c

+9 −6
Original line number Diff line number Diff line
@@ -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;

}